AAMC Flashcards Chemistry/ Ochem Mix
H-NMR region: -NH2
1-5
triple bonds include ___ π bonds and ____ σ bond.
2, 1
Amide reduced to an amine is done with the reagent __________
LiAlH4
Why is water more dense in liquid form than in solid?
This is because the bent structure of the water molecule and ratio of covalently bonded hydrogens to lone pairs of electrons on the oxygen atom maximizes the hydrogen bonding that occurs in the solid phase, producing a hexagonal structure with large empty spaces (IN THE SOLID)
What is a decarboxylation rxn?
Usually you add heat to a B-keto acid which causes dissociation into a ketone and carbon dioxide ex: it can remove a carboxylic acid COO
To form soap, we react _______ and strong ________
carboxylic acid and strong base (NaOH specifically). This forms a structure with sodium carboxylate (polar head) and nonpolar tail
vitamin K refers to a group of closely-related molecules that contribute to blood ___________
clotting/coagulation
Rare earth elements refers to
f-block elements (lanthanides)
Conjugation allows for
fluorescence
phospholipid structure
glycerol + 2 fatty acids + phosphate group
Boiling point for carboxylic acids is _____ than for alcohols
greater
If the reaction shown in Equation 1 is spontaneous, the value of K must be: Eq1: Ca2+(aq) + CO32-(aq) CaCO3(s) A. greater than 1. B. equal to ΔG. C. less than 1. D. equal to zero.
greater than 1.
Phenol
has resonance so make sure that the carbon bonded to OH is also touching a double bond
steroid hormone structure
hydrophobic, small
an enolate acts as a
nucleophile
The majority of metal oxides are ____ at room temp
solid
gamma decay
there is no change in mass or atomic number
Alcohol is _______ acidic
weakly acidic
A circuit similar to that in Figure 2 is set up in which X = Pb, Xn+ = Pb2+, Y = Cu, and Ym+ = Cu2+. Will an oxidation-reduction reaction occur spontaneously?
A spontaneous reaction occurs when E° is greater than zero, and this occurs if the oxidation of Pb(s) is combined with the reduction of Cu2+(aq), resulting in a net E° of +0.466 V. STEPS: I know that I am reacting Pb and Cu in general. X= Pb , X+ = Pb2+, Y = Cu, Y+ = Cu2+ you can imagine that you combine Pb solid with Cu2+ ions in the reactants. Now refer to the table to see whether this combination results in a solid. If it does which it does, then you know that your solid (Pb) got OXIDIZED and your ions got reduced. Therefore flip your Pb reaction since we are currently shown reduced form but we know it got OXIDIZED. Leave the Cu reaction as is because we already established that it got reduced. Then combine them = - (-0.127) + (+ 0.339) = +0.466 If E cell is positive then Gibbs is negative
Nuclear Magnetic Resonance (NMR) Spectroscopy What are some of the rules? hint explain peak #, height, and deshielding
A technique that measures the alignment of magnetic moments from certain molecular nuclei with an external magnetic field; can be used to determine the connectivity and functional groups in a molecule. height: short = has less Hs deshielded to the left if near an oxygen group or near electron withdrawing groups splitting peaks: hydrogens on adjacent carbons will split a peak into n+1 subpeaks , where n is the number of hydrogens on the adjacent carbon MUST KNOW: amide = 5-8.5 region aromatic = 6-8.5 double bond = 4.5-6 single/triple bonds/esters = small aldehyde = 9-10 carb acid = 10-13 alcohol/ethers = 3.4
Acids can be extracted by using _______ since it deprotonates the acid Bases can be extracted with ______
Acids with NaHCO3 (weak base) *aka we usually use something opposite in polarity Bases with HCl ( strong acid)
Which of the following will decrease the percentage ionization of 1.0 M acetic acid, CH3CO2H(aq)? A. Chlorinating the CH3 group B. Diluting the solution C. Adding concentrated HCl(aq) D. Adding a drop of basic indicator
Adding concentrated HCl(aq) You want to first approach this question by realizing that acetic acid is an acid duhhh but also that its fairly weak since it is not one of the strong acids. Therefore if we add HCl which is a strong acid this will increase the amount of H+ in solution and thus decrease the percentage of CH3CO2H that ionizes. In other words, its like a whole bunch of H+ homiez coming to protect acetic acid ( protonating it so that it doesn't lose any Hs)
Assume that cellular uptake rates and drug delivery rates of compounds 1 and 2 are identical. If the proposed mechanism of sensitization by Compound 1 is correct, what cancer cell treatment protocol is most likely to produce the most apoptosis 20 h after treatment? A. Administration of both Compound 1 and Compound 2 simultaneously B. Administration of Compound 1 followed by Compound 2 after 0.5 h C. Administration of Compound 2 followed by Compound 1 after 0.5 h D. Administration of Compound 2 followed by Compound 1 after 1 d
Administration of Compound 1 followed by Compound 2 after 0.5 h *The NF-κB signaling pathway is anti-apoptotic and is initiated by degradation and release of the inhibitor binding protein IκB. Once started, this process is not easily reversed. If the chemotherapeutic agent is administered at the same time as the sensitization agent, there is good reason to believe that some cells will be exposed to Compound 2 prior to Compound 1 as a result of random probability. The researchers found that administration of Compound 1 prior to Compound 2 by 0.5 h provided benefit.
carboxylic acids ranked based on most to least reactive
1. acyl halides 2. Anhydrides 3. Carboxylic acids/esters and esters 4. Amides ( most stable, does not want to react) A rxn that proceeds down the order of reactivity can occur spontaneously by nucleophilic acyl substitution; but if you go backwards then you need special catalysts
H-NMR region: RCH2
1.25
H-NMR region: R3CH
1.5
Adenine contains: ___ pi electrons. One lone pair on N participates in aromaticity. Three lone pairs on N do not participate in aromaticity ( perpendicular to pi electrons)
10
Adenine, Guanine, and Tryptophan contains ____ # pi electrons. Lone pairs on N do participate in aromaticity
10 (since they have 4 double bonds)
H-NMR region: -COOH
10.5-12
What is the period of the voltage source that operates the plasma pencil? A. 2000 ns B. 1500 ns C. 1000 ns D. 500 ns
1000 ns *the period of a time-varying signal is the shortest repetition time. According to Figure 2, each pulse is on for 500 ns, then off for 500 ns. Thus, the time between consecutive pulses is 500 ns + 500 ns = 1000 ns.
IR functional group: conjugated or aromatic C=C
1580-1610
IR functional group: ketone region
1700-1750
Compound X is shown below with three nucleotides. It has how many peptide bonds?
2
H-NMR region: -CHCOOH/-CHCOOR
2-2.6
How many liters of carbon dioxide at STP are produced by reacting 100 g of calcium carbonate with an excess of hydrochloric acid?
22.4L You must first balance the equation: CaCO3 + 2HCl --> CO2 + H20 + CaCl2 From the periodic table, the formula weight of calcium carbonate is 40+12+3(16) = 100g/mol. 100g of calcium carbonate therefore represents one mole, and based on the reaction, this will produce one mole of carbon, and based on the reaction this will produce one mole of carbon dioxide gas. Remember, one mole of any gas at STP has a volume of 22.4L. Therefore, the volume of gas produced will be 22.4: at STP. 100g CaCO3 * 1mol/100g * 1CO2/1 CaCO3 * 22.4L/mol = 22.4L
IR functional group: aldehyde region
2700-2900 AND 1700-1750
In a triacylglycerol, how many equivalents of NaOH do you need to convert to fatty acids and glycerol?
3 equivalents since there are 3 fatty acids
In an exothermic reaction, 3,000J/mol of energy is released when converting reactants to products. the forward reaction has an activation energy of 1200J/mol. What is the activation energy of the reverse reaction from products to reactants?
4,200J/mol. This is bc the exothermic, so energy is released from the forward reaction. The activation energy of the reverse reaction will therefore be the activation energy of the forward reaction added to the amount of energy released from the forward reaction
H-NMR region: Aromatic with OH
4-12
1 atm can be expressed in what other ways
760mmHg = 760torr = 101,325Pa = 1.01*10^5 Pascals
Pka for terminal alpha amino group
8.0
NOrmality
# gram equivalent weight of solute / Liter of solution
"root mean square speed" equation
- the question is asking you to find "root mean square speed" which is U = sqrt(3RT/M) - instead of giving you the equation, it is given implicitly as: KE = (3/2) * KB* T (1/2) mv^2 = (3/2) * KB* T v^2 = [(3) * KB* T] / m v = sqrt [ [(3) * KB* T] / m ] where KB would represent a constant given 1.4 * 10^-23 Mass is the mass of As4 approximately 75g*4 = 300g = 0.3kg ----> we must divide mass by avogadros number
t-butyl
-C(CH3)3
neopentyl
-CH2C(CH3)3
H2CO3 --> H+ + HCO3- what shifts it right?
-increase in pH -adding an alkali earth metal ( adding alkali will lead to the production of hydroxide ions in solution which will react with our H+ thus lowering H+)
What factors increase reaction rate of reaction with gases?
-increase in temp - increase in pressure - increased collision rates between reactants
ion exchange chromatography
-stationary phase is made of either negatively or positively charged beads (attract & bind compounds that have opposite charge) -salt is added to elute proteins stuck to column
0.007 M solution of HI has a [H+] of
0.007 (since it is a strong acid
A bond order of 2 (double) has what bond type, hybridization, angle, and give example
1 sigma & 1 pi, sp2, 120, CdoubleC
A triple bond contains ___ sigma bond and ____ pi bonds
1 sigma, 2 pi
Carboxylic acids are also neat in that we can replace their OH with a nucleophile. How?
1) Nucleophile attacks carb acid, which deprotonates carbonyl 2) the OH acquires an H to become a better water LG 3) deprotonated carbonyl reforms, pushing off water LG * Now you have a a carbonyl with a nucleophile attachment
Synthesis of an alcohol group can happen in what ways:
1) addition of water to a double bond 2) SN1 and SN2 reactions 3) Reduction of carboxylic acids, aldehydes, ketones, and esters - Aldehydes and ketones with NaBH4 or LiALH4 - esters and carb acids with LiALH4 only
Ritonavir is an antiviral drug that mimics the natural substrate for a key viral protease enzyme. As a competitive inhibitor, ritonavir:
decreases the rate of reaction by binding to the active site.
Random order mechanism
either substrate could bind first
Which of the following statements best characterizes a material that is a good insulator but a poor conductor?
electrons in the material cannot easily move from one atom to another ex) plastic, rubber, glass
Hund's Rule
electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible aka everyone gets one cookie first then certain people can get a second cookie if there are leftovers. Mnemonic: "You can think of this as Hund's cookies"
If you have two structures where one has (R,R)- central carbons and is completely the same in terms of attachments to another molecule which is (S,S) central carbons then they are ________ of each other
enantiomers since they are mirror images of each others.
Planck's quantum theory
energy emitted as electromagnetic radiation from matter exists in discrete bundles called quanta
what is the charge of Ag in Ag2S3?
given compound is Ag2S3 - We should know from prior knowledge that S has a charge of 2- therefore (3)(-2) = -6 - Ag must balance the charge on S therefore since Ag has 2 then its charge must be +3
Oxidizing agents
have a high affinity for electrons because their self gets reduced while they oxidize something else will have high affinity for like: O2, O3, Cl2, Mn7+, MnO4-, Cr6+, CrO4 2-
Systems: isolated, closed, or open
isolated: no exchange of energy/matter with the environment. Ex: bomb calorimetry Closed: can exchange energy but not matter with the environment. Ex: = Earth Open: can exchange both energy and matter Ex: humans
atomic weight is the weighted average of the masses of the naturally occurring _________ of an element in amu per atom
isotopes ( same protons, diff neutron number) ex:By looking at C14 wre know this is Carbon 14. The 14 stands for the atomic mass and we already know that Carbon has 6 protons. Therefore mass - protons = neutrons. Neutrons = 14-6 = 8
what is a limitation of IR?
lets say there is a dissapearance of carboxylic acid. However, if there is a a transmission peak that overlaps with the same region or H20 group coordinated to the metal will produce a broad peak that interfered with the analysis
Ea for a Spontaneous reaction
low Ea allows the spontaneous reaction to proceed without outside intervention
Thermodynamic product compared to kinetic product is ____ in free energy
lower
Consider the reaction rate described by the following equation. Rate = k[A]m[B]n The overall reaction is said to be second order when: m and n equal what numbers?
m = 1, and n =1
Moles is the ratio of
mass of a sample /molar mass ****aka we are just cancelling out mass (g)
Isomers
molecules with same molecular formula but different connectivity also called constitutional
What is the stability like for carbocations?
more substituted carbocations are more stable
Number of peaks in NMR equation
n+ 1 ex: In propane, CH2 has three neighboring thus n+1 is done as 3+1 therefore 4 peaks
Anion Exchange refers to the ions being
negative charge so they will stick to a positive column
Enantiomers
nonsuperimposable mirror images; have opposite stereochemistry at every chiral carbon. Same chemical and physical properties except for rotation of plane-polarized light and reactions in a chiral environment have specific rotations of the SAME magnitude but OPPOSITE direction
Small dipole moment
note that electronegativity is used to determine this. We know that electronegativity increased right and up. Also we know that H has a low electronegtaivity (~2.1). O must have the highest electronegativity so it will be most different to H and thus have the highest dipole moment. Te which is lower down the periodic table has the lowest dipole moment since it has low electroneg just like H
Electron-rich molecules function as
nucleophiles (aka they are attackers) For example, amines are good nucleophiles due to the presence of a lone pair of electrons. The carbons in carbonyl groups (C=O) are electron-poor, making them good electrophiles. One of the first steps to take when determining electron density is to look for C atoms bound or near to highly electronegative atoms (O, F, N) and for pi bonds, which can undergo resonance, allowing for molecules to be better nucleophiles.
Ionic bonds
occur between bonded atoms that are very different in terms of electronegativities
ionic interaction:
occur between positively charged residue and a negatively charged residue.
Prostaglandin structure
one 5C Ring, 20 C chain
Amphoteric species
one that can act either as an acid or a base, depending on its chemical environment ex: H20
Nucleotides with phosphate groups, such as ATP, GTP, and those in DNA< are referred to as ________ phosphates
organic
anode is the site of
oxidation
What happens when you mix a primary alcohol and KMnO4?
oxidation to carboxylic acid
2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g) what type of reaction?
oxidation/reduction
A pi bond exists due to the overlap of _____ orbitals between two covalently bonded atoms.
p
Henderson-Hasselbalch equation specifically for pH (acid)
pH = pKa + log [A-]/[HA] note ratio is base/acid
While a mixture of strong acid and strong base has an equivalence of pH 7, a mixture of weak acid and strong base will have an equivalence of pH ?
pH > 7
the log of the ratio of base to acid determines how much ____ differs from ____
pH, pka
pka and ka relationship
pKa = -logKa
When a weak acid (HA) is titrated with sodium hydroxide ( NaOH) in the presence of an indicator (HIn), the pH at which a color change is observed depends on the:
pKa of HIn since the indicator will change color over a specific pH range. The range at which the color change takes place depends on the point at which HIn is converted to In- and this depends on the pKa of the indicator think weak acid + strong base --> higher pH value
Use restriction digest to differentiate between mutant and WT specifically at a _____ site
palindromic ex: AAGCTT
phenoxyl radical
phenoxyl radicals are formed from OH groups so eliminate any answer that shows radicals on carbonyls. Then, we must know that radicals are when a single electron is removed causes instability of the O.
The reaction of R 1-chloro-1-methyl ethyl benzene with NaOH will result in
planar intermediate, forming 50% (S)-1-hydroxy-1-methylethylbenzene and 50% (R)-1-hydroxy-1-methylethylbenzene
Silica gel plate is nonpolar or polar?
polar
dipole-dipole forces ( intermol. force)
polar molecules orient themselves such that the positive region of one molecule is close to the negative region of another molecule
Cation exchange refers to the ions being
positive charge so they will stick to a negative column
if pH < pI use cation exchange because low pH means we have a lot of H+ in solution so a lot of positive, and cation exchange means that our ions are
positive so this makes sense
anhydride prefix and suffix
prefix: alkanoyloxy-, cabonyl- suffix: anhydride
Amide prefix and suffix
prefix: carbamoyl- or amido- suffix: -amide
Gabriel synthesis is used to make
primary amines including alpha amino acids, without overalkylation of the amine
Which amino acids cannot be described as an aromatic heterocycle?
proline (proline has a ring that incorporates the NH2 terminal into itself)
Which of the following solvents would lead to the fastest SN1 reaction? n-hexane benzene tetrachloromethane propanol
propanol (propanol is a polar protic solvent so it would likely go through SN1) * note that tetrachloromethane is actually carbon tetrachloride (nonpolar solvent)
Which of the following types of electromagnetic radiation would have the shortest wavelength? Ejecting an electron from: sp sp2 sp3
sp sp hybridized orbitals have the most s-character so they contain the electrons that are hardest to eject. shorter wavelengths like gamma rays carry more energy
Linear is what kind of s and p combination?
sp ( 180 degrees) ex: BeCl2, CO2 there are two regions of electron density
trigonal planar is what s and p combination?
sp2 ( 120) ex: BH3, BF3, BCl3, acetone 3 regions of electron density ex: acetone is a carbonyl with carbons on either end. It has a central carbon that is bound to three substitutents and has no lone pairs. Thus, the hybridization around this carbon is sp^2, creating a trigonal planar geometry and a bond angle of 120
Trigonal Bypyramidal is what kind of s and p combination?
sp3d ( 90, 120, 180) ex: PCl5, Fe( Co)5 5 regions of electron density
Overall reaction is the reaction form that does not include ______
spectator ions
Surface residues are less likely to be keystones for the protein structure, as those sorts of residues tend to be found in the protein core.
surface proteins are less important
Standard temp and pressure ( STP)
temp: 273K ( 0 degrees) Pressure = 1 atm 1 mole of gas occupies 22.4L
Benedict's reagent
tests for the presence of a reducing sugar, which can either be an aldose or a ketose. A positive result is red precipitate
Which of the following is true of the collisions that take place between gas particles when the scientist lowers the temp?
they will collide without reacting if there is a large decrease in collision energy
Which layer(top or bottom) in the B&D and GC methods in figure 2 is expected to contain sterols isolated from Y.lipolytica extract? B&D: methanol and chloroform Gc: ethyl acetate and ethanol
think about how methanol and ethanol readily dissolve in aqueous solutions Then chloroform has density greater than methanol so it will be at the bottom Ethyl acetate has a density less than ethanol and water so it will be at the top
Charles law
think of Charlie in the chocolate factory which is on tv T and V are directly proportional
Boyle's law
think of a pimple that you are popping P and V are inversely related
Solubility expression (Ksp) does not include
water and liquids Ksp is products only however it can also be reactants in the case that the product is a solid
How should the ideal gas equation be rearranged to most easily use the values from the experiment in the passage to calculate the gas constant?
we want R so isolate for it R = PV/nT.
When do you use HEnderson Hasselbalch equations?
when you want to find the half-equivalence It is likely that A = HA and B = HB for a weak acid and base thus pka = pH and pkb = pOH
Treatment of anhydride with LiALH4 will do what?
will be reduced to a structure with 3 carbons and 2 OHs
Arrhenius acid vs Arrhenius base
Arrhenius acid: produces excess H+ Arrhenius base: produces excess OH
What is the approximate concentration of reaction product in a solution that has an absorbance of 0.7 at pH 6.0? A. 0.50 μM B. 500 μM C. 5 mM D. 500 mM Solution
Based on the equation A = εbc given in the passage, the concentration c is the absorbance A divided by the absorptivity ε in a 1 cm path length cell. 0.7 divided by approximately 1400 gives 500 μM.
Which of the following atoms gains one electron most readily? A.Ar B.Br C.Co D.Na
Br
Bronsted Lowry acid and base
Bronsted Lowry acid: a species that donates protons Bronsted Lowry base: species that accepts H+
Which of the following atoms will be expected to have the smallest second ionization energy? A. Na B. C C. O D. Ca
Ca Metals have lower ionization energies than non-metals as long as the ionization event involves a valence electron. Since Na is an alkali metal, it has only one valence electron and has a large second ionization energy. Ca is an alkaline earth metal and has two valence electrons. It will therefore have the smallest second ionization energy of the four atoms listed, which include Na and two non-metals. I
Which of the following is a second period element that is a covalent network solid in its standard state? A. Carbon B. Phosphorous C. Oxygen D. Iodine
Carbon a second period element that is a covalent network solid (graphite) in its standard state
What is the frequency of the emitted gamma photons? (Note: Use Planck's constant h = 6.6 x 10-34 Js and the elementary charge e = 1.6 x 10-19 C) and KeV = 140
Clearly we can only use E = hf f = E/h = 140keV/ 6.6*10^-34 HOWEVER you need to remember that an electron volt is: V = J/C but since we need energy (J) we need to get rid of C First convert keV units to eV since eV is same as J/C 140keV = 140000eV = 140000 J/C [ (140000J/C ) (1.6*10^-19 C) ] / 6.6*10^-34 = 3.38 × 1019 Hz * note that we got 1.6*10^-19 C from it being the electric charge for a single electron which must be acknowledged in solving
Molar mass of copper II sulfide?
CuS add the mass of copper and sulfur = 95.6
In a carbon with D, OH, and H attachments, what is the priority order?
D has the highest priority simply because it is BIG. After D comes OH then the carbon tail then the H.
Diffusion vs Effusion
Diffusion: occurs when gas molecules distribute through a volume by random motion Effusion: the flow of gas particles under pressure from one compartment to another through a SMALL HOLE same formula: r1/r2 = sqrt [ m2/m1] r : rate m: molar mass
Dissociation of acid in water requires the acid to be _______
Dissociation is your key word Dissociation of acid in water requires the acid to be strong in order to really enjoy dissociating. For example, HCl, H2SO4, and H3PO4 all want to dissociate readily. HPO4 2- has a high negative charge and so dissociation of it will occur to the least extent
How many π-bonds do compounds 1 and 3 have? A. Both compounds 1 and 3 have 6 π-bonds. B. Compound 1 has 6 π-bonds, and Compound 3 has 7 π-bonds. C. Both compounds 1 and 3 have 7 π-bonds. D. Compound 1 has 5 π-bonds, and Compound 3 has 7 π-bonds.
Each double bond contains 1 π-bond and each triple bond contains 2 π-bonds. Therefore, Compound 1 has 6 π-bonds and Compound 3 has 7 π-bonds.
Activation energy of a forward chemical reaction means what?
Energy required to break reactant molecule bonds
ester hydrolysis
Ester hydrolysis: splitting an ester +H20 + H+ -----> alcohol + carboxylic acid
Explain Fischer Esterification general steps
Esterification is used to convert a carboxylic acid to an ester in the presence of a strong acid, heat, and a suitable alcohol. 1) Protonation of the carbonyl by the acid 2) Nucleophilic attack on the carbonyl 3) Proton transfer 4) Water leaves 5) Deprotonation
We use _____ to reduce an ester to two primary alcohols
Esters can undergo hydride reduction with LiAlH4 to form two alcohols.
Given that pka = 6.37 Acid is 2 Conjugate Base is 0.2 Find pH
FOR pH : pH = pka + base/ acid FOR pOH : pOH = pkb + acid/base pH = 6.37 + log ( 0.2 / 2) pH = 6.37 + log ( 10^-1) pH = 6.37 - 1 pH = 5.37
Which of the following elements has the highest electron affinity?
Fluorine
Which halogen has the highest first ionization energy? A. Iodine B. Bromine C. Chlorine D. Fluorine
Fluorine Fluorine has the highest first ionization because it would HATE IF WE REMOVED AN ELECTRON since it is sooooo stable itself and most electronegative than any other element. Since it is so small it has fewer electrons to shield the valence electrons from the nucleus so it will exhibit the highest first ionization energy
Radium (226,88) If it were to undergo electron capture instead of alpha emission, the resulting nucleus would be:
Fr ( 226, 87) Electron capture is similar to B+ decay in which a proton is converted into a neutron so we would expect atomic number to decrease by 1 Radium --> Francium + (B+1)
What is the molecular formula of a compound whose empirical formula is H2SO4 with a molar mass of 588.6?
H2SO4 H = 2.0 S = 32 O = 16*4 = 64 ===== 98 588/98 = 6
polar protic solvents examples
H₂O, NH₃, CH₃OH
osmotic pressure equation
II=iMRT i: # of particles in solution M: molarity R: gas constant T: tempt in Kelvins
Infrared Spectroscopy
IR: used to identify functional groups present on an unknown molecule; relies on much smaller energy absorbance that occurs between various vibrational and rotational states - only molecules that undergo a net chnage in the dipole moment during vibrational and rotational motion can absorb IR radiation - diatomic molecules do not return IR signals because no net change in the dipole occurs - molecules that do respond will bend or stretch
Why do you scratch the side of an erlenmeyer flask?
In order for the liwuid to boil into gas, the liquid needs nucleation sites so that it can start forming bubbles. This is typically either by scratching the inside of the flask or by introducing boiling chips.
torsional strain
Increased energy that results when molecules assume eclipsed or gauche staggered conformations. aka when they are on top of each other or just too close to each other
Filtration separates
Insoluble solids from liquids using a vacuum trap and filter paper in an erlenmeyer flask
"L" amino acids are drawn with hydrogen _____ the plane of the backbone ( dashed line), whereas D-amino acids are drawn with hydrogen in ____ of the plane (solid wedge)
L is behind, D is in front
Lets say you are given an unknown sample of acid with some H2CO3 in it. You titrate it with 0.05M strong base NaOH. In order to find the initial moles of the unknown sample, we would need to know
Lets say you are given an unknown sample of acid with some H2CO3 in it. You titrate it with 0.05M strong base NaOH. In order to find the initial moles of the unknown sample, we would need to know the volume of NaOH (strong base)that was used to reach equivalnce point. This will allow us to mulitply the strong bases molarity by liters to get moles of NaOH. These moles of NaOH will be the same for the initial moles of the unknown acid
Lewis Acid vs Lewis Base
Lewis Acid: electron acceptor Lewis Base: electron donor ex: ammonia since it has a lone air which it can give up ex: NH3 is a stronger base than H20 since nitrogen is less electronegative than oxygen
What are the strong bases?
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
A patient presents in the emergency department having ingested a large quantity of tolbutamide (weak acid). Intravenous administration of which of the following compounds is most likely to increase the rate of urinary excretion of the drug? KCl NaHCO3 NH4ClO4 NaCl
NaHCO3 In order to increase the percentage of drug excreted in the urine, it is necessary to decrease the fraction of tolbutamide capable of reabsorption, or diffusion out of the lumen of the nephron. We must maximize the changed from of tolbutamide ( weak acid) by adding a weak base. This will increase the ionized drug present. Urinary alkalinization can be accomplished by administration of NaHCO3. It is the salt of a strong base (NaOH) and weak acid (H2CO3) so it is a basic salt
NaNO2 + H20 -->
NaOH + HNO2
Rate law for ZERO order - differential rate : - integrated rate : - units:
Note that rate law must be determined experimentally differential rate : R =-K integrated rate : A = Ao * -k * t units: M/s (*this is standard baseline for zero order) The rate of a chemical equation is M/t, with t being in seconds. For a zero-order reaction, rate =k*[A]^0. We set the reaction rate equal to the final units M/s and get the following: k*[A]^0 = M/s. Solving for units of k, we get k = M/s as the units for the rate constant for a zero order reaction
Given that Tris has a pKa of 8.07, for how many of the experiments would Tris have been an acceptable buffer? A. None of the experiments B. Only 1 of the experiments C. Only 2 of the experiments D. All three of the experiments
Only 2 of the experiments *A buffer has a buffering capacity that is +- pH unit away from the pka, which means that only two of the experiments would have used Tris. This is because we are told that Tris has a pka of 8.07 which +- is going to be 7.07 and 9.07. Therefore both the 7.5 and 8.5 fall within this range.
Esters prefix and suffix
Prefix: alkoxycarbonyl- Suffix: -oate
What kind of compound is most likely to be a major product in Step 2 if an aldol condensation is NOT followed by a dehydration reaction?
Remember that an aldol condensation reaction involves two ketone structures where one is a ketone form and one is an enol form, such that the enol attacks the ketone and they combine to form an alpha-beta structure that has a carbonyl. An OH is still intact which is suppose to be removed through a dehydration rxn (removal of water)and thus form a double bond. If dehydration does not occur then we are left with a structure with ketone but more importantly an OH that was never eliminated
A pure sample of (R)-limonene has a specific rotation of +125.6. If a mixture of (R)-limonene and (S)-limonene has a specific rotation of +62.8, what are the percentages of the R and S enantiomers in this mixture?
Since R has a rotation of +125.6 and the mixture of R+S has a rotation of +62.8 then we need to find percentages of each first label x as R percentage (125.6)x + (-125.6)(1-x) = 62.8 125.6x-125.6 + 125.6x = 62.8 x = 0.75 thus 1-x 1-(0.75) = 0.25 Thus R is 75% while S is 25%
In a situation where we are combining solid and aqueous solution, how do we determine whether one element is oxidized? Compare Al and Zn. Let's say we are given info that Al solid does change when mixed with Zn aqueous, but not when Zn solid is mized with Al aqueous
So this one is tricky in the sense that there is sooooo much info provided in the form of graphs and tables but you dont have to use it all at once. focus on what is being compared in the question stem. We are asked to compare Al and Zn in the form of strips. Strips are solid therefore we can refer to the table to see what these would act like when reacted with each others ions. Like Al solid with Zn aqeous and also Zn solid with Al aqeous. We see that Zn solid does not change, but we see that Al solid does change when mized with Zn aqeous therefore it must be more likely to be oxidized.
Reverse Phase Chromatography (RPC)
Stationary phase - nonpolar Mobile phase - polar polar molecules move up the plate quickly, while nonpolar molecules stick more tightly to the stationary phase
In an anhydride, the middle carbon has Hs, why are they important?
The acidity of the proton alpha to 1 or more carbonyls is increased due to stabilization of the anion by resonance
Calcium and magnesium belong to what group on the periodic table? A. The alkali metals B. The metalloids C. The alkaline earth metals D. The halogens
The alkaline earth metals
ideal gas law
The ideal gas law is PV = nRT. There are no intermolecular forces (that is in solids/liquids) Composed of particles that have negligible volume and do not exert intermolecular forces Molar volume of an ideal gas at 25 degrees is 24.4L
Which forms of guanine and thymine are favored under physiological conditions? A. The keto form of guanine and the keto form of thymine B. The keto form of guanine and the enol form of thymine C. The enol form of guanine and the keto form of thymine D. The enol form of guanine and the enol form of thymine
The keto form of guanine and the keto form of thymine *Based on the pKa of the protons on the nitrogen atoms in the rings in Figure 2, the keto state is preferred for both guanine and thymine at physiological pH (7.2) since the pH (7.2) < pka therewe get protonation (most stable since not negative charge to cause tautomerization). The nitrogen atoms are protonated because pH 7.2 is approximately 2 pH units less than the pKa. Note: In general, keto forms always favored compared to enol forms Note: you could also think about the normal structures of T and G from prior knowledge of the structures of bases of DNA and RNA as found in the body. Thymine has 2 C=O and guanine has 1 C=O bond, which would make these the most normal and stable.
Which statement about the unfolding cooperativity and pK of the oligonucleotides is consistent with the data in Figure 1? A. The oligonucleotide with the highest pK displays the highest unfolding cooperativity. B. The oligonucleotide with the lowest pK displays the highest unfolding cooperativity. C. The oligonucleotide with the second highest pK displays the highest unfolding cooperativity. D. The oligonucleotide with the second highest pK displays the lowest unfolding cooperativity.
The oligonucleotide with the lowest pK displays the highest unfolding cooperativity. *pK is the pH at which the fraction of folded DNA is 0.5. This occurs at the lowest value in 5hmC-WT. Cooperativity is measured as the slope of the unfolding transition. This is also highest in 5hmC-WT.
What is the concentration of Ca2+(aq) in a saturated solution of CaCO3? (Note: The solubility product constant Ksp for CaCO3 is 4.9 × 10-9.) A. 2.4 × 10-4 M B. 4.9 × 10-5 M C. 7.0 × 10-5 M D. 4.9 × 10-9 M
The solubility product constant expression for CaCO3 is Ksp = [Ca2+][CO32-]. Since equal quantities of Ca2+(aq) and CO32-(aq) are produced when CaCO3 dissolves, this expression reduces to 4.9 × 10-9 = x2, or 49 × 10-10 = x2. solve for x
Why doesn't chloroform have chemically equivalent hydrogens?
This means that chloroform doesn't have hydrogens with the same atoms surrounding them and with identical chemical shifts.
If we want to change pH of 7.6 to 7.2, then which do we favor between Monoosdium phosphate ( NaH2PO4) and Disodium phosphate (Na2HPO4)?
This one kinda tricky ill give you that. So I understood that in order to go from pH of 7.6 to 7.2 we need to add more acid or reduce basicity in some way. The pka values given kinda threw me off and I felt like I had to use them in some way but you dont have to because it is more conceptual. So first consider answer Choice C. Monoosdium phosphate is NaH2PO4 since (Na is +1, 2H are +2, and PO4 has to cancel it so -3). Disodium phosphate is Na2HPO4 since ( 2 Na is +2, H is +1, and PO4 is -3). Therefore the acid would be the one with the most Hs which is monosodium phosphate. If we favor monosodium then this means we are favoring the acid and increasing acid a bit so that pH will eventually come down from 7.6 to 7.2.
What are the structural features possessed by storage lipids? A. Two fatty acids ester-linked to a single glycerol plus a charged head group B. Three fatty acids ester-linked to a single glycerol C. Two fatty acids ester-linked to a single sphingosine plus a charged head group D. Three fatty acids ester-linked to a single sphingosine
Three fatty acids ester-linked to a single glycerol *triacylglycerols are neutral storage lipids
Based on these data, HCO3- is best categorized as: Substance Ka Kw/Ka H2CO3 4.3 × 10-7 2.3 × 10-8 HCO3 -5.6 × 10-11 1.8 × 10-4 A. a base since Ka > Kb for this ion. B. a base since Kb > Ka for this ion. C. an acid since Ka > Kb for this ion. D. an acid since Kb > Ka for this ion.
a base since Kb > Ka for this ion.
decarboxylation reaction
a chemical reaction that removes a carboxyl group to form CO2 Imagine that you have an alpha, beta double carbonyl with one side being a carboxylic acid. Then, the lone carbonyl will attack the OH from the other carbonyl in a cyclical manner. The thing splits in half, forming enol/keto and CO2.
salt bridge bond
a complex protein interaction which is a combination of two types of interactions: hydrogen bonding and ionic interactions. In a peptide salt bridges occur between acidic aa side chains and basic aa side chains, because they are capable of hydrogen bonding and ionically interacting with one another.
coordinate covalent bond
a covalent bond in which one atom contributes both bonding electrons ex: CuN Copper is a metal and Nitrogen is a nonmetal Essentially the nitrogen is supplying both electrons to them copper (aka coordinate) Cu2+ (metal cation) with Nitrogen atom ( electron pair donor) = coordinate covalent bond ex: NH3 donating its lone pair to H to form NH4
Polyprotic acids
acids with more than one acidic proton ( H+) that can dissociate in water. Each acidic proton dissociates in a stepwise progression that generates a new conjugate base with one less H+ ion until all acidic protons have dissociated. When a polyprotic acid is titrated with a strong base, one equivalent of base neutralizes the first acidic proton in the generic polyprotic acid H2A. Then a second equivalent of base neutralizes the acidic proton in HA- ( conjugate base of H2A)
The lone pair of electrons in ammonia allows the molecule to: A. assume a planar structure. B. act as an oxidizing agent. C. act as a Lewis acid in water. D. act as a Lewis base in water.
act as a Lewis base in water. "electron donor" by definition, a Lewis base is a substance that donates an electron pair in forming a covalent interaction.
When two amino acids join to form a peptide bond this forms a ________ group?
amide
If we wanted to form an amide from oleic acid, why couldn't we just attack with an amine?
amine is a strong base so it prefers to participate in an acid-base neutralization reaction with the acidic hydrogen of the organic acid. Avoid using amine as the first step, instead use PCl5 to create an acid chloride (carbonyl with Cl) which is a better electrophile that amine (nucleophile) would like to attack
Surface active proteins indicates ________ molecules such that they have both hydrophilic and hydrophobic sides
amphiphilic
ping pong mechanism
an enzyme mechanism where a substrate binds to the enzyme and releases a product before the second substrate binds to the enzyme. Double-displacement is another term for ping-pong mechanism, which means that no ternary complex is formed.
Kinetic molecular theory of gases
an explanation of gaseous molecular behavior based on the notion of individual molecules
rate law
an expression relating the rate of a reaction to the concentration of the reactants - the rate law is remembered as only including reactants***** (but wait....) - rate-determining step determines the rate of the reaction and must be included in the rate law. This means nothing downstream from the rate-determining step (substrate and enzymes) is included
In galvanic and electrolytic cells, electrons travel from ____ to ______?
anode to cathode FATCAT
Explain anti-staggered, eclipsed, gauche, and totally eclipsed
anti-staggered: most stable; big groups 180 apart eclipsed: 120 apart gauche: 60 apart totally eclipsed: 0 apart
phenyl chloride is an
aromatic with a Cl sticking off of it
If trifluoroacetic acid is the reagent used in SP synthesis, which of the following would be the most effective for creating an effective support system?
"good support system" means that it will not react with it benzene would be ideal (nonpolar) since it doesn't react with an acid
Molality
# of mol of solute/ kg of solvent
An experiment consists of three separate reactions. The percent yield of the first reaction is 80%, second rxn is 75%, and third rxn is 10%. What is the overall yield of the experiment?
0.8* 0.75*0.1 = 0.06 = 6%
Double bonds consist of ___ σ bond and ____ π bond
1,1
What is the electron configurations of nitrogen that is the most stable?
1s2 2s2 2p3
H-NMR region: RCHCO-
2-2.5
Guanine binds to Cytosine at how many spots?
3 spots ( carbonyl, two rightmost NH and NH2)
Tripeptide factorial
3*2*1 = 6
Which of the following valence electron configurations corresponds to an atom in an excited state?
3s2 3d1 Start with 3s2 which tells us that n = 3 and s represents zero therefore sum them and that is 3 Then look at 3d1 which is n = 3 and d represents 2 so sum them = 5 The difference is 5-3 = 2 which is greater than any of the other answer choices.
Strecker synthesis
A method of synthesizing amino acids reagents: aldehyde, ammonium chloride, and potassium cyanide 1) carbonyl from aldehyde grabs an H from ammonium, forming a positive charged carbonyl 2) ammonia can now attack carbonyl carbon and push off carbonyl to form OH 3) proton transfer from NH3 to OH since we want a good water LG 4) loss of water, 5) cyanide attacks 6) thus forming a nitrile 7) nitrile grabs an H 8) hydrolysis 9) proton transfer 10) hydrolysis 11) proton transfer 12) ammonia loss 13) H loss
acyl halide
Acyl halide is just a carbonyl structure with a halide (goof LG) attached. So you can imagine halide will likely come off if reacted with a primary alcohol. The primary alcohol will attach kind of like O----///. A carbonyl with an O - R group becomes an ester
Aldol condensation
An aldehyde acts as both a nucleophile (enol form) and electrophile (keto form). One carbonyl forms an enolate, which attacks the other carbonyl (aka we start with two carbonyls, one is an enolate w a double bond). After the aldol is formed, a dehydration reaction(removal of water to get a double bond) results in an alpha, Beta unsaturated carbonyl 1) one of the R groups from a ketone forms a double bond, pushing the carbonyl bond off. 2) the O- gets protonated to form OH. 3) the double bond attacks a new ketone again pushing off the carbonyl, and which the O- eventually becomes protonated 4) OH get another H from water so that it becomes a good LG 5) formation of a double bond to get rid of water LG
Which single bond present in nitroglycerin is the LEAST polar? A.C-H B.C-O C.C-C D.O-N
C-C
Describe the isomer tree
CHART FOR COMPOUNDS ISOMERS -> diff connectivity = Structural isomer (aka constitutional) -> same connectivity = Stereoisomer ---> no breaking of bonds: conformational (just flip) ---> breaking of bonds: configurational ------> due to restricted rotation: Geometric (cis/trans) ------> not due to restricted rotation: Optical ------------> non-superimposable: enantiomers ------------> superimposable: diastereomers --------------------> epimers: a type of diastereomer with only one diff chiral C
chain isomer
Chain isomers have different arrangements of the carbon 'skeleton.'
Naming of oxyanions (polyatomic anions that contains oxygen) ClO- ClO2- CLO3- CLO4-
ClO- = hypochlorite ClO2- = chlorite ClO3- = chlorate ClO4- = perchlorate
Energy of an electron equation
E = -Rh/n^2 1.0973×107 m−1
The specific heat of liquid water is 4.2 kJ/°C•kg. How much energy does it take to heat 2 kg of water from 20°C to 70°C? A. 220 kJ B. 320 kJ C. 420 kJ D. 520 kJ
Energy is J or kJ Cancel out units to get these units The energy to raise the temperature of 2 kg of water 50°C (70°C - 20°C) can be calculated using dimensional analysis: 2 kg × 4.2 kJ/°C•kg × 50°C = 420 kJ.
FAD+ --> FADH + H+ means that FAD received ___ proton and ____ electron
FAD+ --> FADH + H+ means that FAD received one proton and one electron
What is a malonic ester synthesis? What is another name for it?
Gabriel Synthesis rxn converts alkyl halides to carboxylic acids Reagents involved: 1) Potassium Phthalamide 2) Diethyl bromomalonate
bent structure examoke
H2S
how do you simplify this? Ka = 10^ (-8.6)
Ka = 10^ (-8.6) which you can maybe calculate in your brain as 1/10^9
What is the total number of sp2-hybridized carbon atoms present in the fluorophore used in the experiments? SEE IMAGE A. 4 B.6 C.9 D.10
Literally count the number of carbons total. The methyl one is the only carbon not considered sp2 since it is bound to four electron dense regions ( aka it is sp3)
_____ solubility would be safest to consume because it means that the the chemical will not dissociate into your body
Low solubility
An unknown amount of a radioactive isotope with a half-life of 2.0 h was observed for 6.0 h. If the amount of the isotope remaining after 6.0 h was 24 g, what would the original amount have been? A. 3 g B. 4 g C. 144 g D. 192 g
Method #1: I did this by starting with 24g and working backwards 6hours in increments of 2hours half life. 24g -[2hr]-> 48g-[2hr]-> 96g-[2hr]-> 192g aka our initial was 192g Method #2: Given the half-life T = 2 h, the duration t = 6 h represents 3 half-lives because 2 h × 3 = 6 h. According to the radioactive decay law N(t) = N0(1/2)t/T, the amount of remaining isotope is (1/2)3 = 1/8 of the original amount. The original amount was then 8 × 24 g = 192 g.
what is the order of priority for these attachments: H, NH2, COOH, CSeH
NH2> CSeH> COOH > H priority is determined by molecular weight
We are given this equation AOm(OH)n, and told "if the central atom, A, is an alkali or alkaline earth metal, the compound is basic. But if A is a nonmetal, the compound is acidic." Question stem: Two additional compounds were studied: NO2(OH) dissolved in water and produced an acidic solution, and Ni(OH)2 dissolved only in an acidic solution. What type of compounds were these?
NO2 (OH) would be an acids since the A part is a nonmetal Ni(OH)2 is considered a metal so it would be a base We can also see this in another manner: The question stem tells us that the NO2 (OH) dissolves in water and produces an acidic solution therefore it must be an acid given that it releases H+. The Ni(OH)2 is dissolved only in acidic solution therefore it must be a basic anion. The OH that is released will quickly react with protons in solution and cannot react again with Ni2+ to form precipitate
Which of the following answer choices contains only empirical formulas?
NO2, C3H8, CH2O
Naming Polyatomic ions containing nitrogen and/or carbon and O NO2- NO3- CO3 2- HCO3-
NO2- = nitrite NO3- = nitrate CO3 2- = carbonate HCO3- = hydrogen carbonate OR bicarbonate (must know both names since you may be given only one in a passage)
nitrogen gas function
Nitrogen exists in diatomic gas state in the atmosphere. Diatomic nitrogen gas is relatively inert and can be used as the atmosphere in laboratory conditions to prevent unwanted side reactions. Nitrogen makes up 80% of air that we breathe but not really chemically active. It is good for nitrogen fixing plants in the soil. It would serve as a good atmosphere artificially when working with reagents that might react with oxygen or other gases
A carbonyl group contains what type of bonding interaction(s) between the C and O atoms? A. One σ only B. One σ and one π only C. One π only D. One σ and two π only
One σ and one π only A carbonyl group contains a C=O double bond. The first bonding interaction between atoms is always a σ bond. The second bond is formed from π symmetry orbitals.
Based on the reaction scheme in Figure 1, what is the mechanism of substrate binding to RT? A. Random order B. Ordered C. Ping-pong D. Double-displacement
Ordered Figure 1 shows that the TP substrate binds first without any catalysis occurring and then the dNTP substrate binds. This is an ordered mechanism.
Explain the mechanism of how we reduce a carboxylic acid to a primary alcohol
Overall, there are two attacks by H- so that we can reduce it 1) H- attacks c of carbonyl 2) the OH acquires an H to become a better water LG 3) deprotonated carbonyl reforms, pushing off water LG 4) another H- attacks c of carbonyl ( here we have an aldehyde) 5) O- acquires an H (now we gave a primary alcohol only)
Naming of polyatomic atoms: Fe(II) Fe (III)
Polyatomic atoms: contain multiple atoms Fe(II) = ferrous ion Fe (III) = ferric ion
positional isomer example
Positional isomers have a given functional group in different locations (e.g., 1-pentanol vs. 2-pentanol).
Amide structure
R-CONH Note that it is carbonyl bound to an NH but the other R side can be anything not just carbons
isocyanate
R-N=C=O
thiol is a R-SH
R-SH
nitrile
RC(triple)N
Which of the following molecules has an octahedral geometry? A. SF6 B. CBr4 C. XeF4 D. BrF3
SF6 SF6 is an AX6 system with no lone pairs As a result, SF6 will adopt an octahedral bonding arrangement to minimize the repulsive interactions of the bonding domain electrons.
Which of the following best approximates the number of ideal gas molecules needed to fill 11.2L of space at STP?
Since 11.2L is half of 22.4L ( aka ideal) then we know 6*10^23 ( aka ideal for 1 mole) will be divided by 2 6*10^23 / 2 = 3*10^23
What is the difference between benzenes that have each one methyl but also an attachment Cl that varies in position ( one is attached 2 carbons away from the methyl while the other is attached 3 carbons away)?
Since the Cl that is attached 3 carbons away from the methyl is equidistant on the benzene then a double bond will only form on one side, replacing chlorine since it would be the same thing if double bond is on the other side. Outcome: 2 diff products However the structure with a Cl that is two carbons away from methyl will be able to form double bonds on either end and create 3 diff products
thin layer chromatography
Stationary phase - polar Mobile phase - nonpolar * silica gel used ex: glucose would move up quickly
In which of the following steps is the carbamate amide group cleaved? A. Step 2 B. Step 3 C. Step 4 D. Step 6
Step 4 The carbamate R2NCO2C2H5 in Compound 3 is cleaved by hydroxide to a secondary amine.
Explain pH at half-equivalence for: Strong Acid Weak Acid Weak Base
Strong Acid: [H+]/2 Weak Acid: use Henderson Hasselback which is pH = pka + log ( A/Ha). Note that A could equal Ha so ratio is 1:1 thus pH = pka Weak Base: pOH = pkb + log (HB/B) then find pH. Note that HB =B so then pH = POH = 14
Freezing point depression vs boiling pt elevation
Tf = i*Kf*m Tb = i*Kb*m BP & BP pressure increases --> vapor pressure decreases, nonvolatile only i = van Hoft factor k = specific constant m = molality
Azimuthal Quantum number "l" refers to
The azimuthal, or angular momentum, quantum number (l) describes the subshell of the principal quantum number in which the electron is found, with values ranging from 0 to n − 1, where l = 0 is the s subshell, l = 1 is the p subshell, l = 2 is the d subshell, and l = 3 is the f subshell. l = 0, 1, 2, 3, s, p, d, f hold a maximum of 2,6,10,14 electrons respectively max number of electrons that can exist within a subshell is given by the equation 4l+ 2
Because pH affects the reaction, a student carefully creates a suitable aqueous solvent for the reaction. After bubbling CO2 through the solution, he checks the pH and is surprised to find that it is not the same as the original value. What is the most likely cause for this? The pH will be more alkaline because the pH of a solution will naturally move to neutral over time. The pH will be more acidic because of the hydrogen gas that is generated. The pH will be more alkaline because CO2 will combine with H2O to create bicarbonate. The pH will be more acidic because CO2 will combine with H2O to create carbonic acid.
The pH will be more acidic because CO2 will combine with H2O to create carbonic acid. H20 + CO2 --> H2CO3 (carbonic acid) --> H+ + HCO3-
Compounds 1-3 bind to a site on RT that is not the active site, and the binding can occur during any stage of substrate binding. Based on the information in the passage, compounds 1-3 are what type of inhibitor? A. Competitive B. Mixed C. Product D. Irreversible
The passage states that compounds 1-3 can bind to RT both before and after the substrate has bound. Also, the compounds do not exclude substrate binding. Therefore, mixed inhibition is most likely.
chelation
The process of binding metal ions to the same ligand at multiple points.
If you have a reaction where we form a carbocation, which is not true? A. The reaction occurs most readily with tertiary alcohols. B. The reaction involves the loss of a water molecule. C. The reaction has a carbocation intermediate. D. The reaction is stereospecific.
The reaction is stereospecific. *Therefore, you would not expect an SN1 reaction have stereospecificity because we can attack from the top or bottom to generate racemic mixture
The formation of [Cu(NH3)4]2+ takes place in a stepwise manner with one water molecule being replaced by an ammonia molecule in each step. In the stepwise formation of [Cu(NH3)4]2+ from [Cu(H2O)4]2+, which of the following ions would form in the second step? A. [Cu(H2O)2(NH3)2]2+ B. [Cu(H2O)2(NH3)3]2+ C. [Cu(H2O)3(NH3)]2+ D. [Cu(H2O)3(NH3)2]2+
The reaction was stated to proceed in four sequential steps, with each step involving the replacement of one water molecule by a molecule of ammonia. As a result, the product of the second step is [Cu(H2O)2(NH3)2]2+
If the titration of H2PO4 - in a urine sample is continued until all acidic protons in the solution are neutralized, how many equivalents of NaOH are needed to complete the titration of the solution?
Two equivalents of NaOH ( one OH from NaOH for each H+) H2PO4- + OH- <--> HPO4 2- and H20 HPO4 2- + OH- <--> PO4 3- + H20
If a student adds a few drops of bromothymol blue (pka =7.1) as an indicator to determine the amount of titratable acid in 25ml of urine according to Folin's method, what effect will the bromothymol blue have on the pH of the urine sample?
WE ARE ADDING JUST AN INDICATOR It will have little effect on the pH of the sample
what could a second order reaction be for 2A + B --> 2C + D?
We are provided an equation 2A + B --> 2C + D. IF we want rate limiting step then that must mean there are two steps involved. You could react a combination of reactants but dont use them all up in one step. For example 2 As cannot react with 1 B because this would mean one step. Rate-limiting step is SECOND ORDER and involves ONLY TWO reactants therefore we could use A + B, B+ B, A+ A only. We could NOT use2A + B
Which of the following compounds is most likely the intermediate product formed in Step 4 of Figure 2 if four equivalents of base are used?
When four equivalents of base (-OH) are used, one -OH will saponify the lactone to form the secondary alcohol and carboxylate, a second -OH will hydrolyze the carbamate, with the remaining -OH as excess.
According to the IUPAC, what is the systematic name for the hydrocarbon shown? A. Z-3-methylpent-2-ene B. E-3-methylpent-2-ene C. Z-3-ethylbut-2-ene D. E-3-ethylbut-2-ene
Z-3-methylpent-2-ene *By IUPAC rules, first identify the longest unbroken chain of carbon atoms. Next, number the carbon atoms in this chain starting from the end that gives C=C the lowest numbers. The double bond is identified by the position of the carbon atom from the lowest numbered end (2), and then the methyl group is assigned at the 3-position. The stereochemical designator for the double bond is Z because the highest priority groups (methyl at C2 and ethyl at C3) occur on the same side of the double bond. The name is therefore Z-3-methylpent-2-ene.
Before coordination to protoporphyrin, what is the ground state electron configuration of Co2+? [Ar]4s23d5 [Ar]4s23d7 [Ar]3d7 [Ar]4s24d5
[Ar]3d7 *cobalt is a transition metal therefore ionization of transition metals will cause electrons from 4s subshell orbitals to be moved to the d orbital so we dont have an 4s at all. This is because electrons on 4s subshell orbitals are higher in energy than 3d subshells.
When limestone is heated during Step 1, an equilibrium is established. Which of the following expressions is the equilibrium constant for the decomposition of limestone? CaCO3 + heat --> CO2 + CaO A. [CaO] B. [CaCO3] C. [CO2] D. [CaO] × [CaCO3]
[CO2] *From the Law of Mass Action, an equilibrium constant expression involves a ratio of products to reactants with exponents determined from the stoichiometry of the reaction. Furthermore, solids are excluded from equilibrium constant expressions. CO2(g), as the only non-solid material in the reaction, is the only substance that appears in the equilibrium constant expression. The exponent for [CO2] is 1 because the stoichiometric coefficient that appears in the presented balanced reaction is 1.
Electron configuration of Ca2+
[Ne]3s^2 3p^6 aka calcium (alkali metal) has lost two electrons
Esterification:
alcohol + carboxylic acid -----> ester + H20
Km is inversely related to
binding affinity
vitamin D is a lipid-soluble molecule primarily involved in _______ metabolism
calcium
What is the chemical formula of calcium sulfate?
calcium sulfate. Since Calcium (Ca) has a charge of 2+ and Sulfate (SO4) has a charge of 2- then we just smush them together without adding extra numbers, CaSO4
vitamin B1 is thiamine and it is considered a _________ in metabolic processes involving amino acids and carbs
coenzyme
what is the difference between dissociation and dissolution(dissolve)?
complete dissociation occurs for strong acids only complete dissolution occurs for strong acids or weak acids (aka both can completely dissolve)
equilibrium constants and Ksp are not affected by _________; instead, only affected by _____
concentrations, temp
Molecular geometry
count the BONDS only
A cysteine-cystine disulfide bond is what kind of bond?
covalent bond since it is made up of two Sulfurs which are nonmetals. There is very little or no electronegativity difference between two bonded atoms, and result in nearly equal sharing of electrons between the two bonded atoms Disulfide bonds are found in tertiary and quartnernary proteins
Z absolute configuration
defines polysubstituted double bonds; Z means 2 highest priority groups are on same side,
the formation of a peptide bond occurs via a ______ reaction therefore the mass of the byproduct is _______
dehydration, water (18g)
A student measures the mass and volume of four objects. Which object has the highest density?
density is mass/volume So choose the one with the biggest mass and smallest volume
what separation technique allows for separation of differing solubilities?
extraction
the dipole moment of aldehydes causes boiling point to ________, but not as high as alcohols because there is no hydrogen bonding
increase
Combined gas law
integrates Boyles, Charles, and Gay Lussacs law P1V1/T1 = P2V2/T2
Solids have _______ entropy than liquids
less
Decreasing the volume of a sample of gas makes it behave _____because the individual gas particles are now in a closer proximity in a smaller volume. However they do now engage in more interactions.
less ideally
percent composition by mass
mass of solute/mass of solution * 100%
In a triacylglycerol, how many stereogenic carbons are there?
only one, the center one
If you treat a hydroquinone with an oxidizing agent(i,e Jones), you form_____-
quinone
What are the products of an SN1 reaction?
racemic mixture of stereoisomers; equal mixture of R and S enantiomers
Free energy is measured as the energy from ______ to ______
reactant height to products height
When electrons are added in the reactants then the reaction what type?
reduction reaction
if you perform carboxylation on a phenol then you get what?
salicylic acid which is just a phenol with an extra attachment that is a carboxylic acid
sublimation is the transition from
solid to gas
Boiling chips/ebullator prevent
superheating
What is more polar: a cyclical hexane that has one alkene with a carbonyl or an OH?
the cyclical hexane that has one alkene and an OH. The OH allows for more resonance which makes it super polar
What does percent yield value indicate about stability?
the most stable product will yield the highest percentage of yield -most likely thermodynamic product
Gay-Lussac's Law
think about TPing Lussacs house T and P are directly proportional
Avogadros principle
think of moles moles n and V are directly proportional since more moles will take up more space
catalysts increase per unit ____
time
A reaction is designed to produce ammonia from the gas phase equilibrium of nitrogen and hydrogen. N2(g) + 3 H2(g) 2 NH3(g) Introducing a catalyst into the system will cause the amount of ammonia at equilibrium:
to remain the same
According to bond length, which has the shortest (single, double, or triple bond)? Why?
triple since it is super strong
Covalent bond is formed by shared ______ between 2 _____
valence electrons between 2 nonmetals
Amines are ____ bases that require storng acids to be protonated
weak
What is the concentration of hydroxide ion for a solution with pH = 10?
pH 10 means H30+ aka H+ concentration is 10^-10 since we just have to take the 10 log of it. Therefore if want to find OH concentration its simple since [H+] * [OH-] = 10^-14 Therefore OH = 10^-4
At pH of 7.2, the charge of the N-terminus during the protein unfolding is going to be?
pH 7 is pretty neutral OH end has a pka of 2 which is < pH so deprotonation = remove H NH2 group has a pka of 9 which is > pH thus protonation = +1 charge
how do you use the (n-1).(10-m) equation given H+ concentration of 4 × 10−8 ?
pH = (8−1).(10−4) = 7.6.
ph equation relating to H+
pH = - log (H+)
Properties of acids and bases
pH = -log (H+) = log (1/H) pOH = -log (OH) = log ( 1/OH) H20 --> H+ + OH- Kw = [H+][OH-] = 10^-14 pH + pOH = 14
Phosphoric acid is a phosphate group or inorganic phosphate (Pi) . At physiological pH which is ___, inorganic phosphate includes both hydrogen phosphate (HPO4 2-) and dihydrogen phosphate (H2PO4 -)
pH = 7.4
Henderson-Hasselbalch equation specifically for pOH base
pOH = pkb + log [HA]/[A-]
diamagnetic refers to when atom's electrons are assigned to an orbital, and we have all ____ electrons
paired
UV spectroscopy involves
passing UV light through a chemical sample and plotting absorbance vs wavelength. It is most useful for studying compounds containing double bonds and heteroatoms with lone pairs.
pka equation relating to Ka
pka = -log Ka pH = pka + log[base/acid] ex: 8.7 = 6.7 + log [HPO4 2-/H2PO4] 2 = log[HPO4 2-/H2PO4] 10^2 = 10^log[HPO4 2-/H2PO4] ratio [HPO4 2-/H2PO4] is 100:1
The starting materials of the Gabriel and Strecker synthesis are all shaped ______; therefore, the product is a mixture of L and D amino acids.
planar (*starting materials are aldehyde for Strecker; diethyl bromo & potassium pthalamide for Gabriel)
A heme has a shape of a ______. The basic unit of this is a ______ which is 5-sided heterocycle containing one nitrogen
porphyrin, pyrrole
Dalton's Law of Partial Pressures
the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual components Ptotal = P1 + P2 + P3... Pa = PtXa Xa = na * (moles of A) nt * (total moles)
How do you determine equivalence point from a titration curve?
the vertical region of the graph; note that there can be on, two, or three first vertical= first H removed second vertical= second H removed third vertical = third H removed ( i.e H3PO4 has its 3 Hs removed so now we jst have PO4 - )
Do they mix: Formic acid and ether?
there are two electron lone pairs on the oxygen of ether so ether will be able to hydrogen bond with formic acid
what is the dipole of CCl4?
there is no dipole since the vertices all cancel each other out
geometric isomers
these are a form of stereoisomers such as trans and cis configurations
colligative properties
these are the physical properties derived solely from the number of particles present, not the nature of those particles. These properties are usually associated with dilute solutions. Molality (m) is often used, in addition to the van't Hoff factor (i) for ionic compounds
How can carb acids be induced to enter the aqueous layer?
they are converted to an ionic salt via deprotonation by either a strong base or weak base.
How can the compounds cholesterol and cholest-4-en-3-one be classified? constitutional isomers structural isomers epimers they are not isomers
they are not isomers cholesterol loses two hydrogens to generate cholest-4-en-3-one so they are not isomers
Which is more acidic: an alpha H next to one carbonyl or next to two carbonyls ( i.e in an anhydride)?
two
Anhydrides can be formed through the dehydration of two ____________
two carboxylic acids 1) one carboxylate carbonyl attacks a carboxylic acid, thus deprotonating carbonyl 2) carbonyl reforms and pushes off the OH 3) Now we have anhydride and water
Simple distillation is used when
two liquids have boiling point <150 and are 25 degrees or more apart
fractional distillation is used when
two liquids have boiling pts that are less than 25 degrees apart refluxes back down over a larger surface area to improve purity
Ubiquinone can be reduced to _______, which can later be reoxidized. This is sometimes called the Q cycle
ubiquinol
polar covalent results when there is a an ____ sharing of electrons which eventually results in a _____ moment
unequal, dipole the electrons in the bond are pulled closer to the atom of greater electronegativity (giving it a partial negative charge) and way from the atom of lesser electronegativity( giving it a partial positive charge). This results in a dipole moment ex: in the compound HF, you have F pulling negative charge away from H, making H positive
Hund's rule states that electrons fill orbitals in such a way to maximize the number of ______ electrons
unpaired
Paramagnetic refers to when an atom's electrons are assigned to an orbital, and we still have ____ electrons
unpaired unpaired electrons will be attracted to an external magnetic field.
Pyrophosphate (PPi) is P2O7 4- which is released during the formation of phosphodiester bonds in DNA. Pyrophosphate is _______ in aqueous solution, and is hydrolyzed to form two molecules of inorganic phosphate
unstable
mole fraction equation
# mol of comp/ total # of moles in system
Molarity
# of moles of solute/ Liters of solution
ionization energy
( opposite of electron affinity); measured the energy required to remove an electron from an atom
Calorimetry problem: Given that 1kg of H20 increases by 50 degrees Cupon combustion of 10 peanuts then how do you find the kcal? 1kcal = 1000cal
(1kg)(1000g/1kg)(1cal/gC)(1kcal/1000cal)(50C) = 50 kcal
Which expression gives the total number of gas particles (NOT moles, but individual particles) found in the lungs of an average human (V = 6.0 L) under normal physiological conditions (P = 1.0 atm, T = 37ºC)? A. 6.0 / (0.0821 * 310) B. (6.0 * 1.0) / ( (0.0821 * 37) C. (0.0821 * 37 * 10^23) D. (6.0 * 6*10^23) / (0.0821 * 310)
(6.0 * 6*10^23) / (0.0821 * 310) The Ideal Gas Law (PV = nRT) must be rearranged to solve for the number of moles of gas particles, n. The result is multiplied by Avogadro's number NA to arrive at the required expression.
isobutyl
(CH3)2CHCH2-
Addition of which disaccharide to a solution of Ag2O in NH3(aq) will NOT result in the deposition of shiny silver mirror on the walls of the reaction vessel? sucrose, maltose, lactose
* Sucrose is the only dissacharide that does not possess a hemiacetal functional group and thus cannot open to form an aldehyde that will reduce Ag+ I know this bc sucrose is the only nonreducing sugar because it cannot be oxidized itself. It has a carboxylic acid so no further oxidizing it possible. On the other hand, maltose lactose both have aldehydes which can be oxidized therefore they are called reducing sugars
Which of the following changes would lead to an increase in atomic radius? -Removing an electron from a K atom to create a K+ ion - Subjecting a dipeptide to proteolysis - Adding an electron to a Cl atom to create a Cl- ion - Removing two electrons from a Ca atom to create a Ca2+ ion
- Adding an electron to a Cl atom to create a Cl- ion
Gabriel Synthesis
- An amino acid is generated from potassium phthalimide (nucleophile) and diethyl bromomalonate, using two SN2 reactions, hydrolysis, and decarboxylation. 1) potassium phthalimide reacts with diethyl bromomalonate via SN2 rxn 2) strong base (NaOH) deprotonates the center H on diethyl bromomalonate 3) Via SN2 rxn R-Br can attack to replace H with R group 4) more NaOH, water, and heat to split the two reagents 5) Add H30+, heat, and decarboxylation to make diethyl bromomalonate into a fully formed amino acid
isopropyl
- CH(CH3)2
A weak acid has what kind of group attached to it?
- Rules for a weak acid: ------> EDG (i.e NH2, tertiary butyl)
What is the structure of B-hydroxyketone?
- a B-hydroxyketone simply means a hydroxyl that is two positions away from the Carbon with the ketone
Explain the reactions of enol ( Michael additions) such that we form M stacking.
- an enolate attacks an α,β-unsaturated carbonyl, creating a bond 1) start with a base (NaOH) that attacks an H from the center carbon 2) an intermediate stage forms (enolate) 3) the intermediate stage attacks the alkene of another carbonyl structure 4) now we have an M shape
Amines, Imines, and enamines all share
- moderate MP/BP - can act as a weak base - contain the root "thio" - act similar to oxygen-containing compounds
Which of the following refers to the mechanism of peptide bond formation? I. Nucleophilic substitution II. Condensation III. Hydrolysis
- nucleophilic substitution ( i.e Gabriel and Strecker synthesis) - condensation ( removal of water)
log10 (0.5/5) = log10 (1/10) = -log10 (10) =
-1
loga(1/a) = -loga (a) =
-1
what is the charge of the image of Pantothenate
-1 since only the carboxylic acid can be affected by deprotonation
what is the charge of the image of phosphopantothenate
-3 since its phosphate OHs are deprotonated and its carboxylic acid deprotonated. -3
Pka for terminal alpha carboxyl group
3.1
H-NMR region: - CHOH/ -CHOR
3.4-4
Imine
A double bond between a carbon and a nitrogen note that the imine can have a lone pair on it by removing an R group has sp2 hybridization just like a carbonyl
disulfide bonds and quarternary structures
A reducing agent will be oxidized itself. The mnemonic is LEORA (loss electrons = oxidized = reducing agent). Therefore, the reducing agent will lose electrons by giving them to cysteine. When the two cysteine groups separate they each go to separate polypeptides. The disulfide bonds MAINTAIN QUARTERNARY STRX therefore when we break disulfide bonds then this causes the 4 strx to separate into multiple polypeptides
What is electron density?
A region of electron density is defined as either a bond (single, double, or triple) or a lone pair of electrons. Two regions yield a hybridization of sp (common in cases of triple bonds or central atoms with two double bonds). Having three regions of electron density is associated with sp2 hybridization, and having four regions yields sp3 hybridization ( due to s, p, p, p)
Which of the following oxidative transformations is unlikely to occur? A. A primary alcohol to an aldehyde B. A tertiary alcohol to a ketone C. An aldehyde to a carboxylic acid D. A secondary alcohol to a ketone
A tertiary alcohol to a ketone *Oxidation of tertiary alcohols is difficult because it involves C-C bond breaking.
Enamine
An amino group attached to a carbon that is double-bonded to another carbon. enamines: can be an N between two Rs or between 3 Rs and NH2 sticking of a single carbon bond next to a double bond
The azimuthal quantum number corresponds with which of the following? The potential energy of the electron Approximate radial size of an electron cloud Approximate geometric shape of the orbital Number of valence electrons orbiting a nucleus
Approximate geometric shape of the orbital aka determines the orbital angular momentum and describes the shape of the orbital
best explains why arginine is more basic than lysine?
Arginine is more bbasic than lysine because the electron-donating groups around the basic nitrogen on arginine make its conjugate acid more stable. Arginine is better able to handle being protonated. In its protonated form, Arginine has electron-donating groups via resonance with other nitrogens, thus it is a more stable conjugate acid
In which of the following molecules does the carboxylic acid functional group have the highest Ka?
High Ka = low pka = very acidic. Most acidic carboxylic acid is one in which there is a nearby F but will be MUCH MORE acidic if nearby 2 Fs. Adding an electron-withdrawing functional group(F lovesssss electrons) provides inductive stabilization of the conjugate base by pulling electron density away from the negatively-charged position. This stabilization increases the acidity of the original compound. Inductive effects increase if the electron-withdrawing groups are closer to the acid and if more of them are present.
Which single bond present below is most likely the shortest? A.C-H B.C-O C.C-C D.O-N
C-H C-H bond is the shortest since hydrogen has a much smaller atomic radius than the second period elements. Also bond with the highest bond enthalpy has the shortest bond length which is C-H ( aka releases a lot of energy since we destabilized something really stable)
What is the net charge of sT-loop at pH 7.2? Note that the amino acid sequence KTFCGPEYLA was generated as a mimic of the T-loop A. -2 B. -1 C. 0 D. +1
C. 0 at pH 7.2, the N-terminus will be positively charged and the C-terminus will be negatively charged. In addition, the lysine side chain will carry one positive charge and the glutamic acid side chain will carry one negative charge.
Question Which saturated fatty acid is the most soluble in water? A. CH3(CH2)10COOH B. CH3(CH2)12COOH C. CH3(CH2)14COOH D. CH3(CH2)16COOH
CH3(CH2)10COOH
sec-butyl
CH3CHCH2CH3
What is the molar mass of methanol?
CH3OH 1C = 12 4H = 4 1O = 16 =32
Which of the following compounds has the greatest hydrogen mass percentage? H20, CH4, H2S, C6H12O6
CH4 has the largest H20 H: (2*1)/20 = 0.1 O: (1*16)/20 = 89% CH4 = 4/16 0.25 H2S = 2/ 34 glucose
Which of the following best describes the bonds between Cu2+ and the nitrogen atoms of the ammonia molecules in [Cu(NH3)4]2+? A. Ionic B. Covalent C. Coordinate ionic D. Coordinate covalent
Coordinate covalent *the Lewis acid-base interaction between a metal cation and an electron pair donor is known as a coordinate covalent bond. One element gives up all its electrons to another molecule
The relative thermodynamic stability of isomeric organic compounds can be inferred from which of the following types of experimental data? A. Boiling points B. UV-visible absorption spectra C. Mass spectroscopic fragmentation patterns D. Heats of combustion
D. Heats of combustion the relative thermodynamic stability of isomers can be determined based on the amount of heat produced when the compounds are combusted; less heat, greater stability.
Which variant of DNA polymerase will most likely retain catalytic activity? A. D429A B. D429E C. D429K D. D429F
D429E D: aspartic acid E: glutamic acid These are most similar *Since the side chain carboxylate groups bind the metal ions, the only variant that would retain this function is D429E.
polar aprotic solvents examples
DMSO, acetone, acetonitrile, dichloromethane
Which of the following does NOT correctly describe the mechanism for the nucleophilic substitution of 2-chloro-2-methyl-butane?
DOES: *SN1 predominate when the electrophile is a tertiary substituted carbon - two step mechanism - carbocation formation - formation of a racemic mixture of products does NOT: - bimolecular rate law (SN2)
The complement to the WT sequence does NOT contain which nucleoside? 5′-TTCCCTACCCTCCCCACCCTAA-3′ A. Deoxyadenosine B. Deoxycytidine C. Deoxyguanosine D. Deoxythymidine
Deoxycytidine
Which term can be used to classify the relationship between two isomers that have the same connectivity but specific rotations of +40 and -25, respectively?
Diastereomers The specific rotation of diastereomers differ in magnitude and may differ in direction
Suppose a blood sample tested above the range (6.0 mg/dL) of the standards used in the experiment. What modification will provide a more precise reading by data interpolation as opposed to extrapolation using the same standards? A. Increase the enzyme concentration. B. Increase the oxygen pressure. C. Decrease the content of oxygen acceptor. D. Dilute the sample with additional solvent.
Dilute the sample with additional solvent. By adding solvent, the concentration of glucose will be lowered, and the resulting absorbance will fall within the range of the standards. This is easily accomplished, and the resulting calculations that account for the dilution are not difficult.
What kind of bond(s) is between NH and O?
Dipole-dipole & London dispersion Intermolecular forces( IMFs) are attractive non-bonding interactions. Common IMFs include Hbonding, dipole-dipole, and London dispersion forces. Dipole-dipole forces exist between any two molecules that contain permanent dipole such as the side chains in between NH-O London dispersion forces exist between all molecules due to transient fluctuations in each molecules electron cloud, which produce temporary dipoles
Which of the following characteristic changes in the IR spectrum would indicate the conversion of a fatty acid to an ester? Disappearance of a broad peak in the 2500 to 3300 cm-1 region only Appearance of a broad peak in the 2500 to 3300 cm-1 region only Appearance of a broad peak in the 2500 to 3300 cm-1 region, disappearance of an intense sharp band in the range 1730-1750 cm-1 The disappearance of a broad peak in 2500 to 3300 cm-1 region, the disappearance of an intense sharp band in the range 1730-1750 cm-1
Disappearance of a broad peak in the 2500 to 3300 cm-1 region only IR spec for fatty acid to ester would differ in that fatty acid has carboxylic acid while ester has carbonyl with O (aka lacks the OH). So you see dissapearance of 2500-3300 region (for OH peak)
electromagnetic energy of a photon equation
E = hc/wavelength
E absolute configuration
E means 2 highest priority groups are on opposite sides
Assuming a 95% yield for each coupling step, what would be the final yield for synthesizing a 10 amino-acid length peptide?
Each time we add an amino acid to the chain, we get 9% pure yield for that step. Here, imagine that each coupling step has a 95% yield and that we are running the cycle 9 times (since no coupling step is needed for the first of the 10 amino acids), with each cycle being independent from the preceeding cycle. Thus,a 10 amino acid peptide would be synthesized in (0.95)^9 = 0.63 = 60% final yield.
Earth is a _______ system
Earth is a closed system according to the passage because there is energy exchange but not mass exchange with the surroundings. Evidence: we are told that earth has had negligible mass exchange with the universe over the past 4 billion years
Ecell equation is in what order?
Ecell = reduction - oxidation
If the strong base solution used in the titration curve shown in Figure 2 was 0.10 M sodium hydroxide and the volume of the glycine solution titrated was 20.0 mL, what was the molarity of the glycine solution?
Equivalence in the diagram presented is at 15ml of NaOH (this is key, always look at your graph labels!!!)so this means we have a 1:1 ratio (equiv point) use your 15ml * (0.010mol/L)(1 glycine/1NaOH) (1/20ml) = 0.075M.
What is the molar solubility of ferrous (II) hydroxide in water at 25°C?
Fe(OH)2 + H20 --> Fe + 2OH [x][2x]^2 = 4x^3 = 3.2 * 10^-14 solve for x
Hematoporphyrin usually forms a complex with:
Fe2+ usually forms a complex with Fe2+. Hematoporphyrin is a close cousin of heme which is the iron-binding cofactor that allows hemoglobin to carry oxygen.
Explain before titration/pH initial for: Strong Acid Weak Acid Weak Base
For Strong Acid = use H+ to get pH by using pH = -log [H+] For Weak Acid use Ka expression which is Ka = [h30][A-] / [HA] aka base over acid. Then lets say u get 10^-4 then your pH is 4 For Weak Base use Kb expression to get pOH then use pH + pOH = 14 to get pH. Note that Kb expression is acid/base
How do you find formal charge?
Formal charge = # of valence electrons - sticks - dots Nitrogen: has 5 valence electrons - ( 4 bonds + 0 electrons) = +1 Left oxygen: has 6 valence electrons - (3 bonds +2 electrons) = +1 Right oxygen: has 6 valence electrons - (1 bond + 6 electrons) = -1
There is a drop in the first ionization energy in going from beryllium to boron. Which of the following best explains the source of this drop?
From periodic table, Be to B means that we are going from being 2s2 to being 2p1. Therefore I ionization is better for Boron since that will turn us into 2s2 which is a maximally filled s. The two valence electrons for ground state Be are in an orbital with an azimuthal quantum number of l = 0 (aka s since 2s2 has the two valence electrons). The third valence electron in ground state boron must be in an orbital with an azimuthal quantum number of l = 1 (aka p orbital)
functional isomer
Functional isomers are isomers where the molecular formula remains the same, but the type of functional group in the atom is changed. For example, a compound with an oxygen atom in addition to several carbon atoms and the corresponding number of hydrogens could be an alcohol with an -OH group, or an ether with a C-O-C group.
Galvanic vs Electrolytic
Galvanic, G = -, E = + (spont.) * uses a salt bridge and 2 containers * This type of energy is harnessed by placing the oxidation-reduction half reactions in separate containers called half cells. The half cells are then connected by an apparatus that allows for the flow of electrons Electrolytic, G = +, E = - (nonspont.) * uses a battery circuit and usually just one container * electrical energy is required to induce a reaction. electrons are driven in through the cathode and drawn out through the anode.
Gas X has a density of 1.44 g/L and gas Y has a density of 1.54 g/L. Which gas diffuses faster?
Gas X, because it has a lower mass than gas Y
When choosing a buffer to use for an experiment conducted at pH 5.3, it would be best to choose one with a pKa of:
Good experimental design protocols state that a good buffer has a pKa within 1 pH unit of the desired experimental conditions. Within this range, there is less than a 10 to 1 ratio of acid to base or base to acid forms of the buffer, and so some buffering capacity still remains.
In naming a compound, OH takes priority even if it will make a shorter chain ( pentanol over hexanol)
Got it
Elements stable with fewer than 8 electrons
H(2), He(2), Li(2), Be(4), B(6)
The following reaction occurs spontaneously. Cd(s) + 2 H+(aq) → Cd2+(aq) + H2(g) Which of the following has the highest electron affinity?
H+ since it gained electrons and got reduced to H2 which has an oxidation state of 0
Which of the following species has the largest mass percent of oxygen? A. H2O B. CaCO3 C. CO2 D. HCO3- Solution
H20 2*H = 2 1*O = 16 = 18 total oxygen/total =16/18
H2S has a similar structure to:
H20 (both are bent)
given pka of H2PO4-/ HPO4 2- = 6.7, then what is the initial ratio HPO4 2- to H2PO4
H2PO4 <--> HPO4 2- + H+ Ka = [HPO4 2-][H+] / [H2PO4] plug in values
weak acid ( HA) + base ( H20)
HA + H20 --> H30+ + A-
General equilibrium equation for dissociation of an acid:
HA + H20 <--> H30+ + A-
What is the approximate pH of a saturated aqueous solution of hydrochloric acid whose molarity is 10.6 M?
HCl acid is a strong acid and completely dissociates in aqueous solution. In this solution, the hydronium ion concentration is 10.6M, which can be approximated as 10M to make the math easier. The pH is -log of the hydronium ion concentration therefore log10 = -log[10^1] = -1 While the typical pH range is normally thought of as ranging from 0 to 14, if the concentration of hydronium ion is greater than 1M, negative pH values are possible. It is also possible to have pH values greater than 14, i.e if the hydroxide concentration is greater than 1M.
What are the strong acids?
HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4 Bro so I have no clean clothes
Which of the following is a weak acid in aqueous solution? HF HCl HBr HI
HF will produce less ions has unusually high degree of covalent bonding between the fluorine and the hydrogen
Which of the following acids is expected to generate hydrogen bonding? HI HF HCl HBr
HF Hydrogen bonding is a unique type of intermolecular force that occurs when H is bonded to very electronegative elements like F, O, N. Fluorine is the most electronegative element on the periodic table. Of the answer choices, only hydrogen fluoride is capable of hydrogen bonding.
Which of the following statements explains why the boiling point of HF is abnormally high when compared to the boiling points of other Group 7A hydrides?
HF is affected by hydrogen-bonding interactions to a much greater degree than the other Group 7A hydrides. Hydrogen bonding is a special type of intermolecular force that happens when H is bonded to highly electronegative elements such as N, O, and F. Because hydrogen bonding is a higher than anticipated dipole-dipole interaction, it causes substances that exhibit it to have higher than expected boiling points and lower vapor pressures.
Each of the following equations shows the dissociation of an acid in water. Which of the reactions occurs to the LEAST extent? A. HCl + H2O → H3O+ + Cl− B. HPO42− + H2O → H3O+ + PO43− C. H2SO4 + H2O → H3O+ + HSO4− D. H3PO4 + H2O → H3O+ + H2PO4−
HPO42− + H2O → H3O+ + PO43− *HPO42- has a high negative charge and so dissociation of it will occur to the least extent. Also NOTE that this is NOT a strong acid
Which of the following chemical species is NOT isoelectronic with a neon atom? He, F-, Mg2+, Na+
He F- means a fluorine that gains one electron Mg2+ is magnesium that loses two electrons Na is sodium that loses one electron All of these except He end up being Neon
Which of the following governs the dissolution of vaporized iodine into an alkaline solution?
Henry's Law state sthat the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid. Thus, a higher partial pressure above the alkaline solution will result in more iodine gas becoming dissolved
A gas that occupies 10 L at 1 atm and 25C will occupy what volume at 500 atm and 25C?
High pressure = low volume 10/500 = 0.02 Somewhat more than 0.02L because of the space occupied by the individual gas molecules Simply think about the ratios. 10L to 1atm, how many L to 500atm
Which amino acid is found in greatest abundance in the active site of a laccase? A. Phe B. Tyr C. His D. Cys
Histidine ( aka has two double bonds and two Ns in its ring)
Hydroxynitrobenzene are molecules with both an OH and an NO2. If any two of these groups are too close, they will hydrogen bond together via
Hydroxynitrobenzene are molecules with both an OH and an NO2. If any two of these groups are too close, they will hydrogen bond together via INTRAmolecular bonding. This makes the molecule less likely to form intermolecular bonding. Intra bonds are easier to separate and dont require uch energy therefore lower melting point. They are also less soluble meaning that they are less likely to inter bond with water solvent = low solubility.
Naming of monoatomic ions H- O2-
Monoatomic ions H - = hydride O2- = oxide
Chiral carbons
Must have 4 diff attachments Solutions of chiral compounds rotate planes of polarized light at angles unique to each compound --> clockwise rotation (+) of plane polarized light = "d" --> counterclockwise (-) of plane polarized light = "l" specific rotation can be calculated: [a] = a/c*l a = observed rotation c = concentration in g/ml i = the length of the polarimeter tube in decimeters
imine is an
N double bonded to a carbon
nitro structure
N single bonded to two Os and to one R
ribosome synthesis occurs in what direction of terminals ?
N-terminal to C-terminal
Azide
N3- Note that the image shows one form but we can rearrange to form: R(single)N(single)N(triple)N
For a structure that is connected to one single central carbon by the following 4 substituents: - NH2 - COOH - CH2NHR - H (on dash) *these ar ein counterclockwise What is priority?
N> C so NH2 is priority 1 C-O > C-N so COOH is priority 2 CH2NHR is priority 3 H is priority 4 and it is already on dash so means it is facing back so no need to change it Counterclockwise = S configuration
What is the role of NADP+ during conversion of glucose-6 phosphate to 6 phosphogluconate
NADP+ gets reduced itself so it is an oxidizing agent
What is the rate law for an SN2 reaction?
Rate = k [substrate][nucleophile] SN2 is bimolecular, ***** rate determining step is the attack of a nucleophile onto the electrophilic atom of a asubstrate
Acetic acid and ethanol react to form an ester product as shown below. In determining which reactant loses the -OH group, which of the following isotopic substitutions would be most useful? A. Replace the acidic H of acetic acid with D. B. Replace the alcoholic H of ethanol with D. C. Replace the carbonyl oxygen of acetic acid with O-18. D. Replace the hydroxyl oxygen of ethanol with O-18.
Replace the hydroxyl oxygen of ethanol with O-18. **Labeling the oxygen in ethanol with O-18 definitely determines which -OH is lost because 100% of the O-18 in radiolabeled ethanol will be retained in the ester, not the water. Thus, only acetic acid supplies -OH that is lost to form water.
The environment of the retinal binding site is most likely: A. hydrophilic. B. positively charged. C. negatively charged. D. hydrophobic.
Retinal is composed of mainly carbon and hydrogen, making it largely hydrophobic.
All natural chiral amino acids except cysteine have ____ configuration
S configuration
sulfoxide is
S double bonded to O R-S(=O)-R'
thioketone is an
S double bonded to a carbon
sulfonyl
S double bonded to two Os and single bonded to two Rs
Entropy of the universe
S universe = S system + S surroundings
Sulfate ion
SO4 2- CAN BE DRAWN IN AT LEAST 6 DIFFERENT RESONANCE FORMS many of which have two double bonds attached to a different combination of oxygen atoms
Under anaerobic conditions, bacteria can sometimes derive energy from the oxidation of sulfur-containing species. Sulfur in which of the following compounds would be LEAST likely to be oxidized by an anaerobic bacteria? H2S SO4 2- S2O3 2- S8
SO4 2- SO4 2- will be least likely to be oxidized because the highest oxidation number of sulfur +6 ( loss of all its electrons). We know that O in SO4 2- has a charge of 2- therefore (-2)(4) = -8. We also know that SO4 has an overall charge of 2- thus this should be the resulting number when combining S and Os. Since O is -8 then S must be +6 so that we get overall -2. Thus SO4 2- is already fully oxidized
STP vs Standard conditions
STP (used for gas law calculations) 0 degrees ( 273K) 1atm Standard conditions (used for enthalpy, entropy, Gibbs, and electromotive force) 25 degrees = 298K 1 atm 1 M concentration
Which of the following molecules will have the highest Rf value when studied with thin-layer chromatography using a silica plate?
Silica is a highly polar molecule; thus, when chromatography is done on a silica plate, a polar substance will move slower on the plate due to polar-polar interactions between the substance and the plate. This means that the Rf value of a polar substance will be smaller than that of a nonpolar substance since the substance will move less on the plate compared to the solvent front than a nonpolar substance would.
One method of isolating polypeptides and proteins from aqueous extracts is freeze drying. The aqueous solution of the polypeptide or protein is frozen. What procedure can be used to remove the water from the frozen sample? A. Sublimation under reduced pressure B. Distillation using steam C. Extraction with organic solvent D. Addition of magnesium sulfate
Sublimation under reduced pressure (solid --> gas) Sublimation of the water under reduced pressure will keep the mixture cold and will maintain the protein in its native state.
What allows small insects to walk on the free surface of water? A. Hydrostatic pressure B. Viscosity C. Buoyancy D. Surface tension
Surface tension *Small insects walk on the free surface of water because, at the air-water interface, all hydrogen bonds in water face downward, causing the molecules of the water surface to bond together. Due to cohesion, the polar water molecules do not cling to nonpolar molecules (such as oils) like those found in the insect feet. The insects do not sink through the free surface of water provided their weight is smaller than the surface tension.
If compound 4a makes up 60% of the product compared to compound B (40%) then which is more stable?
comp A (thermodynamic product)
Diamagnetic refers to atoms that have electron configuration in which electrons are _____
completely paired with each other ex: Calcium = [Ne] 3s2, 3p6, 4s2 ex: Ca2+ = 3s2, 3p6 ex: Sr = [Ar]4s2, 3d10, 4p6, 5s2 aka they are all paired and we have no weird situation of like 3s1 or 3p3
In order for molecules to be the same they must have same __________ at the same chiral centers
configurations
sp2 is key word for _____
conjugation so we expect that light will be absorbed and colors are seen
If a homogenous catalyst cannot be separated from the products at the end of a reaction the the products will be ________
contaminated (aka the reaction can still occur but your products will be messy)
A balloon has a volume of 3.0 L at 25°C. What is the approximate volume of the balloon at 50°C?
convert celsius to kelvin and make fractions to compare them 3L/ 300K = V2/320K V2 = 3.3L
The Na2CO3 used in Step 5 of Figure 3 is necessary to: A. dissolve the bromoester. B. remove an α-hydrogen from the bromoester. C. convert the ammonium salt in Compound 4 to the amine. D. replace the chloride ion in Compound 4 with the carbonate ion.
convert the ammonium salt in Compound 4 to the amine. Na2CO3 acts as a Brønsted base. Until a proton is removed from the alkylammonium salt in Compound 4, it does not have the lone pair needed to be a nucleophile. As a nucleophile, Compound 4 performs the SN2 reaction that furnishes Compound 5.
lactams
cyclic amides ( aka a carbonyl in a cyclic structure that is next to a NH as also in the structure) B-lactam y-lactam d-lactam E-lactam
lactones
cyclic esters aka an ester inside a cyclic structure a-acetolactone B-propiolactone y-butyrolactone d-valerolactone
The transition from a vapor phase directly to a solid form is known as: condensation freezing sublimation deposition
deposition gas to solid ( aka deposite is like a precipitate)
What deprotonates an alpha hydrogen?
deprotonated with a strong base such as alkoxide (C2H5O-)
Diastereomers
differ at one or more stereocenters but have the orientation of at least one stereocenter in common specific rotations differ in magnitude and direction
Rate law for SECOND order - differential rate : - integrated rate : - units:
differential rate : R = A*B integrated rate : A = 1/A = 1/Ao + kt units: 1/Ms We set the reaction rate equal to the final units to get the following k*[A]^2 = M/s. We get k*M^2 = M/s. Solving for units of gives us 1/M*s
Rate law for FIRST order - differential rate : - integrated rate : - units:
differential rate : R = k*A integrated rate : A = Ao * e^(-kt) units: 1/s We set the reaction rate equal to the final units and get the following: k*A = M/s
What reaction do oyu use for pH initial
dissocian constants Ka = [H30][A-] / [HA] Kb = [B+][OH-] / [BOH]
How to calculate dilution factor?
divide the final volume of the dilute solution by the volume of solute solution transferred Vfinal/ Vtransferred if you have two or more dilutions events them just multiply all them together such as (Vf/Vt)*(Vf/Vt)*(Vf/Vt) .......etc
If the system involves aqeous substances, how will volume affect the equilibrium?
does not affect it since there are no gases
A compound with a high negative charge ______ dissociate
does not want to
Pauli exclusion principle
each orbital within a subshell can hold a MAX of two electrons, which must have opposite spins.
what is stereospecific?
easier to comprehend if you separate out the word roots such as stereo = stereocenter while specific = one particular outcome. Therefore, you would not expect an SN1 reaction have stereospecificity because we can attack from the top or bottom to generate racemic mixture
Electron-poor molecules function as
electrophiles (these get attacked by nucleophiles) Such molecules function as electrophiles in reactions that yield covalent bonds, as Brønsted-Lowry acids when making a bond to an H+, or as Lewis acids when coordinate bonds are formed.
Leucine amino acids are hydrophobic so rather be inside. So if they are moved to outside then they cause _____ change.
entropy
IF a graph shows the changes of concx on the y-axis and the time on x-axis along with equilibrium at 6M ( horizontal line), then how many moles of the product are present in a 750ml sample of reaction mixture?
equilibrium at 6M ( horizontal line) which is out concentration 6M = 6mol/L 6 mol/L * 0.750L = 4.5 mol
If you react acetic acid with ethanol or any primary alcohol in general, what is your result?
ester Esters are formed from the combination of carboxylic acids and R-OH. In fact you should know that the R-OH will be incorporated completely into the ester formation. Therefore the OH on the carboxylic acid will be used to form water side product.
What are the components in a transesterification reaction?
ester + 1 alcohol --> swap attachments
saponification reaction
ester + NaOH --> soap The reaction between an animal fat and a strong base. Produces soap and glycerol (a trihydroxy alcohol). *if saponification resulted in 4 fatty acids then one fatty acid must have been unsaturated so it isomerized
What is the net charge on a phenylalanine molecule at pH 1?
net +1 ph< pka pka of phenylalanine = approx 6 ths lots of H+ in solution NH2 gets protonated to NH3+ = +1 OH gets protonated to OH = no change
beta minus decay
neutron is converted to proton (so atomic number increases) you should expect the element to be of a larger atomic number
How many moles of atoms are in 8 moles of nitric acid?
nitric acid: HNO3 there are 5 moles of atoms (H, N, 3*O) in 1 mole of nitric acid but we want # in 8 moles therefore 5 x 8 = 40
Carboxylic acid derivatives can be interconverted through _______
nucleophilic acyl substitution by swapping leaving groups
What are Substitution reactions?
occur after protonation or leaving group conversion ex: tertiary alcohol + HBr 1) protonation of OH into water 2) Br- attacks and removes water LG ex: secondary alcohol + Tosyl chloride + NaI 1) tosyl chloride makes OH a better LG 2) NaI attacks and removes entire LG
Pi (π) bonds occur between two parallel ____ orbitals and are weaker than σ bonds
p
IR functional group: carboxylic acid region
1700-1750 AND 2800-3200 (broad)
The intravenous solutions used to correct fluid imbalances in trauma patients are aqueous solutions of glucose. Approximately how much glucose is needed to make 1.0 L of a 100 mM solution? 18mg 34mg 18g 34g
18g
electron configuration
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p Note that 4s comes before 3d Also note that we dont get f until we reach 4f.....
Pentane is a straight-chain hydrocarbon with the molecular formula C5H12. How many additional structural isomers can be constructed using this molecular formula?
2 additional tertiary and quarternary forms
What is the approximate energy of a photon in the absorbed radiation that yielded the data in Table 1? (Note: Use 1 eV = 1.6 × 10-19 J and hc = 19.8 × 10-26 J•m.) A. 1 eV B. 2 eV C. 3 eV D. 4 eV
2 eV The photon energy is E = hc/λ = 19.8 × 10-26 J•m/(625 × 10-9 m) = 3.1 × 10-19 J ≅ 2 eV. You can also just focus on getting the desired units from the given values ( aka you want eV in the numerator)
How many hydrogen bonds are present in the two types of G•T mismatches discussed in the passage? Note: G•T mismatches occur in two different ways. In the wobble base pair, the G•T mismatch appears as an offset A•T base pair. In addition, the G•T mismatch can mimic a G•C base pair if the enol tautomer of T is present. A. 2 in the wobble pair, 2 in the enol T mismatch B. 3 in the wobble pair, 2 in the enol T mismatch C. 2 in the wobble pair, 3 in the enol T mismatch D. 3 in the wobble pair, 3 in the enol T mismatch
2 in the wobble pair (AT), 3 in the enol T mismatch (GC) *Since the wobble base pair appears as an offset A•T pair, it has two hydrogen bonds. The G•C mimic mismatch would have three hydrogen bonds. This can be directly inferred from it mimicking the G•C pair or by examination of the enol T structure.
H-NMR region: -C(triple)CH
2-3
H-NMR region: -CHX
2-4.5
If all of Gas X (from Step 6) is held in a sealed chamber at STP, what will be its approximate volume? Step 6: The chemist heated enough NaHCO3(s) from Step 5 to produce 1 mol Na2CO3(s), 1 mol H2O vapor, and 1 mol of a gas (Gas X). The chemist collected Gas X for further study. A. 22.4 L B. 44.8 L C. 67.2 L D. 89.6 L
22.4 L The quantity of Gas X was given as 1 mole. One mole of gas occupies 22.4 L at STP.
1 mole of gas at STP =
22.4L
Four substances [Al(s), Al3+(aq), Cu(s), and Cu2+(aq)] are mixed. What is the reaction?
2Al(s) + 3Cu2+(aq) → 2Al3+(aq) + 3Cu(s) This response depicts the balanced chemical reaction that occurs when the four substances [Al(s), Al3+(aq), Cu(s), and Cu2+(aq)] are mixed. Reactants must have one solid and one aqueous; and products must too.
Approximately how many moles of Al3+ are reduced when 0.1 faraday of charge passes through a cell during the production of Al? (Note: Assume there is excess Al3+ available and that Al3+ is reduced to Al metal only.)
0.033 mol 1 Faraday = 1 mole of electrons 0.1 Faraday = 0.1 mole of electrons Since 3 moles of electrons are needed to reduce 1 mole of Al3+, then 0.1 mole of electrons will therefore reduce to: 0.1 mole e-* [(1 mole of Al3+)/(3 moles of e-) ] = 0.033 moles Al3+
Because strong acids and bases completely ionize, the [H+] and pH (or [OH−] and pOH) are easily calculated, since the concentration of protons or hydroxyl groups is equal to the molarity of the solution. Thus, a 0.4 M solution of KOH has a [OH−] of
0.4
H-NMR region: RCH3
0.9
A single bond contains ___ sigma bond
1
What do you use for oxidation for 1,2,3 alcohols?
1 or 2: strong or weak oxidizing agent like - weak: PCC - strong: KMnO4, K2Cr2O7, CrO3 3: cannot be oxidized Note that oxidizing a 1 alcohol with PCC only oxidizes it to aldehyde which can then be oxidized with an strong agent to form carboxylic acid Note that 2 alcohols regardless of strength of agent used, will only oxidize to a ketone
What kind of bond activity occurs when we have a benzene with a halogen and then form a carbocation in place of the halogen?
1 pi bond broken, 1 sigma bond formed
A bond order of 3 (triple) has what bond type, hybridization, angle, and give example
1 sigma & 2 pi, sp, 180, CtripleC
A bond order of 1 (single) has what bond type, hybridization, angle, and give example
1 sigma, sp3, 109.5, C-C bond
How do we form an amide form anhydride?
1) a primary amine attacks an anhydride which causes deprotonation of one carbonyl 2) the central O steals a proton from the amine that is stuck on there, which now puts a positive charge on central O 3) this allows the carbonyl to reform and split off from the positive central O 4) Now we have an amide and a carboxylic acid
Intermolecular bonds
1) hydrogen bonds( i.e methanol) 2) Dipole-dipole (HCl - HCl) 3) Dispersion forces (London, temporary unequal sharing) 4) disulfide bridges, which is a type of intermolecular covalent bonding.
What do we do if we want to form an amide from an ester?
1) use ammonia to attack an ester 2) forms amide and primary alcohol ( aka this was the attachment on the ester)
H-NMR region: CHOH-CH2OH
1-5.5
Solubility rules
1. All salts containing alkali metals ( group 1) or ammonium ( NH4) cations are WATER SOLUBLE 2. All salts containing the nitrate NO3)or acetate (CH3COO-) anions are WATER SOLUBLE 3. All chlorides, bromides, and iodides are WATER SOLUBLE, with the exception of Ag+, Pb2+, and Hg2+ (AgCl clearly a solid) 4. All salts of the sulfate ion (SO42-) are WATER SOLUBLE ( except Ca, Sr, Ba, Pb) ~~~~~~INSOLUBLE~~~~~~~ 5. All metal oxides are INSOLUBLE except alkali metals (NaOH is good, CaO, SrO, BaO 6. All hydroxides are insoluble except w alkali, Ca, Sr, Ba 7. All carbonates, phosphates, sulfides(S2-, and sulfites (SO3 2-) are insoluble except w alkali and ammonium
To be classified as aromatic, a compound must have:
1. Conjugated pi bonds in cyclic structure 2. Unhybridized p orbitals present in each atom in the ring 3. Planar geometry, forming a continuous ring of parallel, overlapping unhybridized p orbitals 4. 4n + 2pi electrons ( Huckel rule), where n is a non-negative integer
Magnitude of proton or electron charge?
1.6*10^-19 C ex: any time I am given protons produced we can put this over (1.6*10^-19C) to get the number of electrons removed
The pH scale is logarithmic (pH = -log([H+]). A difference of 3 pH units corresponds to a ________-fold difference in proton concentrations.
10^3 = 1000
According to Table 1, what is the concentration of the glucose in the blood from which the diluted sample was taken? Note: In a test, a blood sample with 1/30 dilution ratio was mixed in a transparent cuvette with an oxygen-acceptor solution containing glucose oxidase. A. 60 mg/dL B. 90 mg/dL C. 120 mg/dL D. 150 mg/dL
150 mg/dL From Table 1, the glucose concentration in the diluted sample is (0.20/0.24) × 6.0 mg/dL = 5.0 mg/dL. The blood then has a glucose concentration of 30 × 5.0 mg/dL = 150 mg/dL.
At STP, the volume of N2(g) produced by the complete decomposition of 1 mole of nitroglycerin would be closest to which of the following? 4C3H5N3O9(l) → 12CO2(g) + 10H2O(g) + 6N2(g) + O2(g) A. 5 L B. 10 L C. 20 L D. 30 L
30 L Based on the balanced equation provided, 4 moles of nitroglycerin produce 6 moles of N2(g). Therefore, 1 mole of nitroglycerin will produce 1.5 moles of N2(g). At STP 1.5 moles of N2(g) will occupy 33.6 L since the molar volume of an ideal gas at STP is 22.4 L/mol. I
Which temperature range corresponds to the cold plasma used to sterilize a wound? "Cold plasmas" (plasmas with temperatures around 35°C. A. 393-423 K B. 363-373 K C. 303-313 K D. 273-283 K
303-313 K
IR functional group: alcohol region
3100-3500 (broad)
IR functional group: amines region
3100-3500 sharp
If a reaction releases 188.6 J, what is the ∆H of this reaction in reverse which has double the stoichiometric coefficients? 188.6 J 377.2 J -188.6 J -377.2 J
377.2 J We are told that a reaction releases 188.6J which means that enthalpy is a NEGATIVE value (released, H = - ). So if this reaction is run in reverse then it would have to be positive. You must still double the values since we are told to double the stoichiometry.
Aspartic and glutamic acid pka
4.1
H-NMR region: -CH(double)CH
4.6-6
Thymine, Cytosine, and Uracil contain ___ # pi electrons. Lone pairs on N do NOT participate in aromaticity ( perpendicular to pi electrons)
6 (since they all have three double bonds & it doesn't matter if double bond is in a carbonyl or in the ring)
What is the concentration of the acute leukemia CC95 Combination value in micromolar (μM) units? Leukemia: CC95: 44nM CC combination: 0.6nM A. 6 × 10-10 μM B. 6 × 10-7 μM C. 6 × 10- 4 μM D. 6 × 10-2 μM Solution
6 × 10- 4 μM The CC95 Combination value for acute leukemia cells was 0.6 nM, or 0.6 × 10-9 M. This corresponds to 0.6 × 10-9 M × (1 μM/1 × 10-6 M) = 0.6 × 10-3 μM = 6 × 10-4 μM.
H-NMR region: Aromatic
6-8.5
Histidine pka
6.0 only basic in pH >6
Avogadros number
6.02 x 10^23
The glucose meter measures the current produced during Reaction 2. If 0.67 μmol of electrons were measured, what mass of glucose was present in the sample? (Note: The molar mass of glucose is 180 g/mol = 180 μg/μmol.) A. 20 μg B. 60 μg C. 90 μg D. 270 μg
60 μg the stoichiometry of the reaction is 2 mol e- per mole of glucose consumed. The device measured 0.67 (2/3) μmol of electrons, indicating that 0.33 (1/3) μmol of glucose was consumed. This weighs 60 μg, based on its molar mass of 180 g/mol.
H-NMR region: RCHO
9-10
Electronegativities: Ionic Polar covalent Covalent
> 2.0 difference = ionic (NaCl, MgCl) 0.5 < x < 2 = polar covalent ( H2O, NH3, HBr, SO2) < 0.5 = covalent ( think of CO, NO, H2, O2, CH4)
If an unknown compound is completely dissolved in water and weakly conducts in electricity. The hydrogen ion concentration of the unknown aqueous solution is 1*10^-5 therefore what comp is it? (weak acid, weak base, strong acid, strong base)
A weak acid can dissolve in water, but cannot completely dissociate in water. From the aqueous solution (1E-5), you know the pH=5 (I believe this was the previous question) you can deduce this is an acid. If you didn't know that that number represents a weak acid, you go to the weakly conducted electricity, and that tells you that it is a weak acid. A strong acid will completely dissolve and completely dissociate while acting as a strong electricity conductor. A weak acid will completely dissolve and partially dissociate while acting as a weakly electric conductor. vs. for strong/weak base.
Which structure represents a component of the HRP cofactor? SEE IMAGE
A. because the cofactor is heme, which is a porphyrin. The basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom
Compared to treatment with Compound 2 alone, which cell line shows the greatest enhancement of chemotherapeutic activity as a result of sensitization by Compound 1? A. Acute leukemia B. Fibrosarcoma C. Cervical carcinoma D. Noncancerous fibroblast
Acute leukemia *The ratio of the values of CC95 to CC95 Combination, gives the "fold enhancement" that is produced by using a combination of compounds 1 and 2 instead of just Compound 2 alone. Acute leukemia cells show a 74-fold enhancement in apoptotic activity by using the combination of compounds 1 and 2, while the other cancer cell lines show only a roughly 10-fold enhancement.
The equilibrium shown in Equation 3 can be shifted to the left by which of the following? 2Na(-bead)(s) + Ca2+(aq) --> Ca(-bead)(s) + 2Na+(aq) A. Adding more resin B. Adding Ca2+ ions C. Adding Na+ ions D. Increasing the concentration of anion on the plastic beads
Adding Na+ ions
The equivalence point of the titration of tolbutamide (pka = 5.3) with NaOH was reached by adding 50 mL of NaOH. Which of the following correctly describes the solution during this process? The solution had a pH less than 7.1 at the equivalence point. After addition of 25 mL of NaOH, the pH of the solution was greater than 5. The concentration of the charged form of tolbutamide was greater than neutral tolbutamide during the titration. The concentration of the charged form of tolbutamide was less than neutral tolbutamide during the titration.
After addition of 25 mL of NaOH, the pH of the solution was greater than 5. If 50ml of NaOH represents the volume of titrant required to reach the equivalence point, then 25ml is the volume added at the half equivalence point. At this point, one half of the original tolbutamide present will have been converted to its conjugate base, and their concentrations will be equal. According to Henderson Hasselbach equation, when the values of protonated acid and conjugate base are equal, pH = pka + log 1. Therefore ph = pka. At the half-equivalence point, pH of the solution equals the pka of the analyte (~5.3) so greater than pH>5 is a feasible answer.
AgNO3 + Zn → 2 Ag + Zn(NO3)2 Split this into two half reactions
AgNO3 + Zn → 2 Ag + Zn(NO3)2 can be split into two half-reactions: (1) a reduction half-reaction for silver (Ag + + e- → Ag) and (2) an oxidation half-reaction for zinc (Zn → Zn2+ + 2 e-). We know this because any element on its own (i.e Ag) is an solid and on the left of the reaction we see AgNO3 (Ag must be an ion) while Ag on the right is alone ( must be a metal) therefore we must reduce the ion(remove the +) by adding electrons to it to form a metal.
Which of the following are properly balanced complete combustion reactions? I. CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (l) II. C3H8 (g) + 5 O2 (g) → 3 CO2 (g) + 4 H2O (l) III. C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (l)
All 3 we know they are combustion because they start with hydrocarbons ( combination of C, H, and/or O) mixed with O2 which leads to carbon dioxide and water all are also balanced
Let's say you have a cyclic structure that has methyl and an OH attachments. If you you add HCl to this, what will happen?
All this means is that acid (H+) from the HCl will react with the structure. Importantly, we know that there are acidic Hs already on the cyclic structure that can leave and form a carbocation on the structure. Acidic protons will usually leave at the carbon adjacent to the carbon with the OH. Then it will be attacked in such a way to form a double bond. Double bonds like to be in the position that is more substituted simply because they are more protected that way. They will also form on either side of the OH, causing the OH to leave. Another approach is that the H+ will protonate the OH and make it a good leaving group such that the Cl- will then want to attack it and Cl will stick on the structure.
The pH of a 1 L phosphate buffer solution was measured as 7.6, but the experimental procedure calls for a pH 7.2 buffer. Which method will adjust the solution to the proper pH? (Note: The pKa values for phosphoric acid are 2.2, 7.2, and 12.3.) A. Add enough 1 M Na2HPO3 to increase the phosphate anion concentration ten-fold. B. Add 1 M NaOH to neutralize a portion of the hydronium ions found in the solution. C. Alter the ratio of monosodium/disodium phosphate added to favor the monosodium species. D. Add 100 mL distilled, deionized water to dilute the basicity of the buffer.
Alter the ratio of monosodium/disodium phosphate added to favor the monosodium species.
Amide Condensation:
Amide Condensation: replace the carb acid OH with amide (H2N-CH3)
Phosphorus appears directly below nitrogen in the periodic table. The boiling point of ammonia, NH3, is higher than the boiling point of phosphine, PH3, under standard conditions. Which of the following statements best explains the difference in the boiling points of these two compounds?
Ammonia forms stronger intermolecular hydrogen bonds than phosphine. Therefore, it requires more heat to overcome the intermolecular forces
Which of the following functional groups is present in pyrrolizidine (Figure 1)? A. An amide B. An amine C. An imine D. A carbamate
An amine *Pyrrolizidine contains a nitrogen atom bonded to three noncarbonyl carbon atoms, which is an amine. An amine is defined as R3N, where R = H or a carbon group (but NOT C=O) and no more than two out of three R groups can be H.
Addition of which of the following amino acids would MOST effectively interfere with sodium hydroxide's ability to induce an in vitro saponification reaction (performed under approximate biological conditions) with triacylglycerols? Leucine Valine Proline Arginine
Arginine is the only positively charged amino acid presented compared to the other three nonpolar. It function to neutralize of bind to a negative charge in saponification ( aka disturbs/interferes with its normal ability). This is because the hydroxyl of the triacylglycerols has a negative charge that operates as both a base and a nuclephile. We can therefore interfere with its action by providing an alternate stronger nucleophile, or by neutralizing it to prevent it from acting as a base. We are specified that the reaction is happening under conditions that approximate biological activity, so we should assume that arginine is present in its physiologic (positive) form. Hydroxide is a very strong base, so it would be able to deprotonate the positive arginine side chain. This would neutralize at least some of the hydroxide ion in solution, thereby interfering with its activity
Tell me the charge difference between: Arginine to Glycine Lysine to Aspartic Acid Methionine to Aspartic acid tyrosine to cysteine isoleucine to methionine
Arginine to Glycine indicates + 1 charge to 0 thus loss of -1 Lysine to Aspartic Acid indicates +1 to -1 thus a loss of -2 Methionine to Aspartic acid indicates 0 to -1 thus a loss of -1 tyrosine to cysteine has no change = neutral isoleucine to methionine has no change = Neutral
what kind of amino acids can contribute to the stabilization of ADP binding?
As basic amino acids, both His 11 and Arg27 could be positively charged in the binding site of PanK3 and create electrostatic attractive forces with the phosphate groups of ADP.
Based on the information in the passage, which description of an enzyme-substrate covalent intermediate is most likely correct? The substrate is covalently attached to: A. Asp14 through the phosphorus atom of the phosphate group. B. Asp14 through the oxygen atom of the phosphate group. C. Asp16 through the phosphorus atom of the phosphate group. D. Asp16 through the oxygen atom of the phosphate group.
Asp14 through the phosphorus atom of the phosphate group. *We are told in the passage that the active site of G3PP contains Asp 14 and Asp 16, which act as nucleophile and general acid, respectively during catalysis. We are looking for the best description of a substrate covalent intermediate which is occurs through the nucleophilic substitution by the side chain carboxyl of Asp 14 at the electrophilic phosphorus atom in the substrate, displacing a leaving group.
Net charge of the peptide composed of the amino acids KYCR
At a ph of 5 it is acidic so we are protonating all the Os and NHs in our amino acids. K is lysine (pka = 10.8) which has an NH2 so we protonate it to +1 Y is tyrosine (pka =10.9) so it has an OH which is already protonated so = 0 C is cysteine (pka=8.3) which has SH and its already protonated so = 0 R is Arginine(pka = 12.5) so it has NH2 so we protonate it so = +1 Overall = +2
The graph below shows the relationship between the predominant form of iron as a function of solution pH and applied potential. Based on the graph, which of the following statements is true? A. At a potential of -0.4 V, as pH increases, Fe2+ is reduced and precipitates as Fe(OH)3. B. At a potential of -0.44 V, the equilibrium between Fe and Fe2+ is independent of solution pH below pH 6. C. At pH = 1, as the potential is changed from -0.2 to +0.8, Fe3+ is reduced to Fe2+. D. At pH = 8 and V = -0.1 V, Fe(OH)2 is the predominant form of iron.
B. At a potential of -0.44 V, the equilibrium between Fe and Fe2+ is independent of solution pH below pH 6.
Which expression can be used to calculate the solubility of CaCO3? A. Ksp = [Ca2+][CO32-]/[CaCO3] B. Ksp = [Ca2+][CO32-] C. Ksp = [CaCO3]/[Ca2+][CO32-] D. Ksp = [Ca2+]2[CO32-]2
B. Ksp = [Ca2+][CO32-] (for CaCO3), Ksp is equal to the product of the calcium ion concentration and the carbonate ion concentration, [Ca2+][CO32-]. The solubility product constant expression Ksp can be derived from the Law of Mass Action. Remember that CaCO3 is a solid therefore it is not included
Channel X transmits only the smallest substances dissolved in the extracellular fluid through the axon membrane. Which substance does Channel X transmit? A. Proteins B. Sodium ions C. Potassium ions D. Chloride ions
B. Sodium ions Sodium cations are small by virtue of their positive charge and low atomic number. Of the answer choices, sodium cations are the smallest.
NMR detects hydrogen atoms by exposing them to radio waves that excite atoms from the alpha spin to the ____ spin state . It applies an external magnetic field B0 and radio frequencies to a sample
BETA
The chemical process that occurs during acidosis can be replicated in vitro by adding a strong acid to an ammonia buffer solution. How will the pH of the solution change if 1.0ml of 0.5 H2SO4 is added to a 100ml solution containing equal amounts of 1M NH3 and 1 MNH4?
BUFFERS RESIST CHANGE the pH will DECREASE slightly ( <1.0 pH units) because NH3 and NH4+ act as a buffer Strong acid added is much less than the concentration of NH3. NH3 in the buffer reacts with the H+ ions from the added H2SO4 (strong acid). Formation of NH4 (weak acid) gives only a slight change in solution pH.
Balmer vs Lyman series
Balmer: the group of hydrogen emission lines corresponding to transitions from upper levels n>2 to n=2 Lyman: "think lower down" transitions between upper levels n>1 to n=1
Lets say that Ka (presence metal ions) while Ko (binding constant of CPFX-BSA in the absence of a metal ion) are in a ratio of Ka/K0. IF we are shown a table with Ka/K0 = 0.80 then the metal ions present in plasma are expected to have what effect on the binding affinity of CPFX to BSA
Based on table 2, we get the metal ions and we get the Km. We want to actually look at the column that is Ka/K0 because this will help answer the effect that Ka (with metal) has on K0 ( without metal). Since it is a ratio of Ka/K0 then we know that binding would be the same (aka no effect) if Ka/K0 was = 1. However we see that we have decimla values which means that Ka must be lower than K0. For example, if Ka/K0 = 3/4 = 0.75. Therefore if Ka(with metal ions) is lower then it has a higher binding affinity. So it will decrease the amount of CPFX bound to BSA.
In experiment 1, which additional extraction steps would cause phosphatidylethanolamine and 2,6-dimethozyphenol to enter the aqueous layer consecutively?
Because the question says that phosphatidylethanolamine should enter the aqueous layer first, followed by 2,6-dimethozyphenol, heir ionic salts must be formed in sequence. Phosphatidylethanolamine contains an amine ( weak base) group that can be protonated to form a water-soluble ammonium salt NH4. Therefore a strong acid such as H2SO4 should be added first to protonate the amino group. In contrast, 2,6-dimethozyphenol has a weakly acidic hydroxyl group ( pka = 10_ on the benzene ring that must be deprotonated to form an ionic salt. Only strong bases such as NAOH can deprotonate phenols. So first add a strong acid and then a strong base.
How does Gabriel Synthesis begin?
Begins with an SN2 reaction, where potassium phthalimide is the nucleophile that attacks an alkyl halide. The amine is then deprotected by the removal of the phthalamide group. for the synthesis of amino acids, potassium pthalamide is the nucleophile that attacks the electrophilic carbon of diethyl bromomalonate, and bromide is the leaving group. The alpha carbon is deprotonated with a base and attacks an alkyl halide to add the amino acid side chain via another SN2 reaction. The phthalamide is removed through a basic hydrolysis reaction, yielding a dicarboxylic acid. Lastly, the diacid is decarboxylated with acid and heat. The resulting loss of CO2 yields the final amino acid. The starting reagents for this synthesis are planar and do not have chiral centers; therefore the amino acid product will be a mixture of L and D amino acids
Based on the data in Table 1, what are the effects of increasing pH on catalytic efficiency and the maximum velocity of the reaction? A. Both the catalytic efficiency and the maximum velocity of the reaction increase. B. The catalytic efficiency increases with pH, but the maximum velocity of the reaction decreases. C. The catalytic efficiency decreases with pH, but the maximum velocity of the reaction increases. D. Both the catalytic efficiency and the maximum velocity of the reaction decrease.
Both the catalytic efficiency and the maximum velocity of the reaction decrease. Note: 2 key eqs Catalytic E = kcat/km kcat = Vmax/ [E] Aka so as pH increases on the table, Cat E decreases. Since kcat is proportional to Cat E and Vmax is proportional, then they all decrease too *As pH increases, the kcat decreases because it is proportional to the Vmax. Also, the catalytic efficiency (kcat/KM) decreases because Vmax/KM is decreasing.
Radioactive tritium (3H) labeled guanine has been used to measure the rate of biochemical processes that involve its binding or incorporation. Given that water is the solvent for this type of experiment, what is the best site for tritium labeling? A. I B. II C. III D. IV
I the best site for tritium labeling would not exchange the tritium ions for protons in water. All of the N−H sites (II−IV) would readily exchange tritium protons due to their lone pair-facilitating protonation and subsequent tritium exchange with water, but the C−H site (I), lacking a lone pair, would retain its tritium label.
Based on the information shown below, under which conditions in step 1 will 1-methylpiperazine react with diethylcarbamyl chloride to form diethylcarbamazine?
I have to identify that the structure of 1-methylpiperazine is the one with the N-H attachment. Therefore, I need a strong base like NaOH to remove the H so that the 1-methylpiperazine can act as a nucleophile and attack diethylcarbamyl chloride to form diethylcarbamazine. NOTE THAT THIS IS ALWAYS THE METHOD: treat an acid with a base; treat a base with an acid = essentially this activates the reaction
An oncology team wants to treat a patient with a 10 mL tumor with the same protocol that was used for this study. How many moles of porfirmer should they use? values given: the concentration of 2.5ug/ml of prifirmer molar mass is 599g/mol each molecule of porfirmer contains an average of 8 units
I legit was missing a piece of information in order to cancel out units. Note that this info can be provided in words in the passage rather than straight up numbers. The researchers treated their cells with a concentration of 2.5ug/ml of prifirmer. We're treating a 10ml volume, so 2.5ug/ml * 10ml = 2.5 * 10^-5g. To convert grams to moles we need molar mass and that is 599g/mol which we can round to 600. However the question tells us that each molecule of porfirmer contains an average of 8 units so 8* 600g/mol = 4,800g/mol. This can be used in the calculations 2.5 * 10^-5g. / 4,800g/mol = 5*10^-9
What is the dilution for the following stepwise event? A standard solution was formulated by diluting 0.5ml of the organic layer with enough solvent to give a total volume of 10ml. A sample of 0.5ml of the resulting standard solution was then diluted with 0.5ml of solvent to yield a 1.0ml NMR sample.
I simply determined the factor difference from 0.5ml to 10ml which is that we multiply by x20. dilution factor #1 0.5*20 = 10 Then we also took 0.5 ml of the this 10ml and combined it with an equal amount of solvent (0.5) which is a 1:1 ratio with a final concentration of 1ml for both. So you divide your final volume ( 1ml) by volume transferred ( 0.5ml) which gives you 2. Multiply dilutions together: Therefore 20*2 = 40
What is the concentration of Cl- ions in a 0.1 M solution of calcium chloride?
I simply took 0.1M => 0.1 mol/L CaCl2 and multiplied by 2mol of Cl-/1 mol of CaCl2 = (0.1) (2/1) = 0.2 of Cl
Which of the following will contribute to the level of Fluorodeoxyglucose(FDG) signal seen during a PET scan of the colon? I. Blood flow to the tissue II. Availability of oxygen to the tissue III. GLUT4 transport
I. Blood flow to the tissue II. Availability of oxygen to the tissue If there is less blood flow, there is less FDG present in that tissue. IF there is less oxygen available to tissue, there is less oxidative respiration and smaller need for FDG. However, GLUT4 is an insulin-regulated glucose transporter found in adipose and striated muscle (skeletal and cardiac). The presence of GLUT4 transporters in tissue would not affect the amount of FDG in a GI tissue such as the colon
Surfactant-substrate interactions can involve which of the following intermolecular forces? I. London dispersion forces II. Hydrogen bonding III. Ion-dipole interactions
I. London dispersion forces ( between all bonds since e's are constantly moving and creating interactions) II. Hydrogen bonding (H and OH from different molecules) III. Ion-dipole interactions ( + and - side of two different molecules)
Which of the following reactions could be used to synthesize amino acids in the laboratory? I. Strecker Synthesis II. Grubbs Synthesis III. Gabriel Synthesis
I. Strecker Synthesis: uses aldehyde and KCN III. Gabriel Synthesis: uses K+ thalamide and a strong base, alkyl halide The MCAT also expects you to be aware of two classical reactions used to synthesize amino acids in laboratory conditions: the Strecker synthesis and the Gabriel synthesis. Although these reactions have the same basic output— an α-amino acid—they're very distinct processes. The Strecker synthesis starts with an aldehyde where the carbon chain corresponds to the side chain (or R) of the amino acid that we're trying to synthesize, and that aldehyde is then reacted with KCN and NH4Cl to form an aminonitrile. In an acidic aqueous environment, hydroxyl groups are added across that triple bond until, with appropriate proton juggling, we form an amino acid. The high-level logic of the Strecker synthesis is shown below: Although the Strecker synthesis is a complicated, multistep process, it boils down to three basic steps: (1) take an aldehyde and convert the carbonyl group to an amine; (2) add a nitrile group, which provides an extra carbon and a scaffold in the form of a triple bond for subsequent addition of water; and (3) keep adding water to that triple bond and shuffling protons around until the amine can be kicked out to generate a carboxylic acid. The hallmarks of this approach are the clever use of nitrogen-containing reagents and multiple hydration and proton transfer steps. The logic of the Gabriel synthesis is quite different, as it involves taking a process for synthesizing primary amines and "hacking" it to generate amino acids. In fact, the term "Gabriel synthesis" can refer more broadly to the amine synthesis step, so let's take a look at that first, as depicted in the figure below. The amine synthesis step starts with a very carefully protected nitrogen atom, most commonly in the context of a molecule called phthalimide. The first step is to deprotonate that nitrogen atom, at which point it can be reacted with an alkyl halide. In that reaction, the halide is kicked off of the alkyl chain, and the alkyl chain is essentially added to the nitrogen atom, which is still also part of the phthalimide molecule. The task is now to remove that nitrogen atom from the phthalimide ring structure to form a primary amine. This is actually quite complicated, and there are multiple ways of doing it. Traditionally, an important reagent for this process was hydrazine, shown on the bottom left of the figure, which will yield phthalhydrazide plus our product of interest, a free primary amine. Acid hydrolysis can also do the job, as shown in the bottom right of the figure, and yields our primary amine plus phthalic acid. Base-catalyzed hydrolysis would also logically enough yield the primary amine plus phthalate, the conjugate base of phthalic acid.
How do you make an alcohol a better leaving group for nucleophilic substitution reactions? What should you add to it?
Mesylate or tosylate
What is the difference between mesylate and tosylate?
Mesylate: -SO3CH3 Tosylate: -SO3C6H4CH3
Imagine you perform mass spectrometry showing the yellow precipitate to contain two absorption peaks, correlating to both a phosphate group and a silver component. Therefore the common ion effect accounts for: I. the observed increase in yellow precipitate as recorded in Figure 2 when AgNO3 is added. II. the observed increase in yellow precipitate as recorded in Figure 2 when K3PO4 is added. III. the observed decrease in yellow precipitate as recorded in Figure 2 when Ba(OH)2 is added.
I. the observed increase in yellow precipitate as recorded in Figure 2 when AgNO3 is added. II. the observed increase in yellow precipitate as recorded in Figure 2 when K3PO4 is added. The common ion effect occurs when a solution contains a salt that fully or partially dissociates into its ions, and one of these ions is added to the solution ( the common ion). This results in a decrease in solubility of the salt. In this case, the partially dissolved salt is Ag3PO4. Addding AgNO3 or K3PO4 will lead to precipitates due to the overlapping ions already present.
Ibuprofen has a structure that contains one ring, a carboxylic acid, and an isobutyl [(CH3)2CHCH2- ] it is most similar in shape to glucose ATP glycerol Palmitoleic acid
Ibuprofen has both a hydrophobic part and a polar carboxylic acid. Like ibuprofen, palmitoleic acid has a hydrophobic part (its long carbon chain) and a polar carboxylic acid. Thus, palmitoleic acid most likely binds to the same site as ibuprofen in BSA.
Factors that improve separation in distillation
Improve - elongate the column - slight increase in pressure - heat at a slower rate No effect - cooling the condenser
What volume of a 0.120 M CaI2 solution would contain 0.078 mol of the solute? A. 35.0 mL B. 65.0 mL C. 350 mL D. 650 mL
In order to obtain the volume of solution necessary to provide a given amount of solute in moles, one needs to take the number of moles and divide by the solution concentration in molarity: 0.078 mol × 1 L/0.120 mol = 0.65 L = 650 mL.
Which is a better leaving group and why? Iodine or Fluorine
Iodine is a better leaving group because it is larger Good leaving groups tend to be electronegative because they are able to withdraw electron density from the carbon-leaving group bond, making the substrate carbon more electrophilic. However, more importantly, the size of a leaving group is one of the most important factors bc a large leaving group is able to stabilize the negative charge conferred by leabing the substrates. Leaving groups often have a negative charge once they leave the substrate , because they carry they carry with them the electrons from the carbon-leaving group bond. Thus, while fluorine is more electronegative than iodine, the more important factor to consider is leaving group size ( which means that iodine is the more stable leaving group)
What is the electron configurations of Iodine?
Iodine is not a transition metal so there is no exception to the rule that we can shift around the electron configuration. Therfore, [Kr]5d10, 5s2, 5p5
Ionic radius
Ionic radius cations (+) are smaller in size (smaller ionic radii) than uncharged elements since charged elements must lose an electrons Anions (-) are typically larger than uncharged state ex: F- is larger than F
In order to measure the ∆G, researchers needed to denature the proteins. Which of the following steps would be LEAST suitable for this procedure? Increasing temperature Irradiating the protein with non-ionizing radiation Adding a concentrated chaotropic agent Lowering the pH
Irradiating the protein with non-ionizing radiation * does not break bonds
System processes
Isothermal : T = 0 Adiabatic: Q = 0 Isobaric: P = 0 Isovolumetric/isochoric: V = 0
What is the role of the solid-state catalyst in the Haber process? A. It increases the amount of ammonia produced per unit time. B. It increases the total amount of ammonia produced. C. It decreases the amount of ammonia that decomposes per unit time. D. It decreases the total amount of ammonia produced.
It increases the amount of ammonia produced per unit time.
Which of the following functional groups is found in benzoin, C6H5CH(OH)C(O)C6H5?
Ketone Benzoin contains a ketone carbonyl group and an alcohol hydroxyl group. It has no carboxylic acid, ether, or aldehyde. Thus, answer choice D is the best answer.
what are the predominant species in the phosphate buffer system and in the ammonia buffer system in an aqueous solution at a pH of 8? H2PO4- <--> HPO4 2- + H+ pka = 6.8 NH4+ <--> NH3 + H+ pka = 9.1
Key notes: ph = pka then acid and base concentrations are equal pH> pka then deprotonated pH< pka then protonated We expect HPO4 2- and NH4+
A student plans to add HCl to a solution containing Pb(NO3)2(aq). To determine how much Pb2+ will precipitate from solution when the HCl is added, the student needs to know the Ksp for which substance and why?
Ksp for PbCl2 To determine how much Pb2+ will precipitate, the student must know the solubility of PbCl2, which is related to the solubility product constant Ksp of PbCl2.
Natural amino acids have "L" because it is incorporated into amino acids, while D cannot be incorporated
L is the way to go
With which of the above metals can copper form a galvanic cell in which copper is reduced?Start with what does galvanic refer to?
Lead and zinc E cell = reduction- oxidation We know copper is reduced since its reaction has electrons in the reactants side. We also want Ecell to be positive. Ecell = copper - (oxidized metal) The oxidized metal has to be a negative value so that we can get a positive Ecell.
Consider the reaction shown in Equation 1 at equilibrium. Would the concentration of [Cu(NH3)4]2+ increase if the equilibrium were disturbed by adding hydrochloric acid? [Cu(H2O)4]2+(aq) + 4NH3(aq) -->[Cu(NH3)4]2+(aq) + 4H2O(l) A. Yes, because the equilibrium in Equation 1 would shift to the left B. No, because the equilibrium in Equation 1 would shift to the left C. Yes, because the equilibrium in Equation 1 would shift to the right D. No, because the equilibrium in Equation 1 would shift to the right
No, because the equilibrium in Equation 1 would shift to the left Hydrochloric acid will protonate ammonia in a Brönsted acid-base reaction and reduce the amount of ammonia present. The disturbed equilibrium responds in a way to restore ammonia, but this causes the amount of [Cu(H2O)2(NH3)2]2+ to decrease. This means that the equilibrium shifts to the left.
During Reaction 2, did the oxidation state of N change? NH3(aq) + CO2(aq) + H2O(l) → NH4+(aq) + HCO3-(aq) A. Yes; it changed from -3 to -4. B. Yes; it changed from 0 to +1. C. No; it remained at -3. D. No; it remained at +1.
No; it remained at -3. * The part of Reaction 2 that involves nitrogen is the protonation of ammonia (NH3 + H+ → NH4+). Acid-base reactions do not involve oxidation state changes. The oxidation state of N in NH3 is -3. Each H is +1 and is balanced by the -3 of N to make a neutral compound. The oxidation state of N does not change when the N is protonated.
Formation of an aldehyde through nucleophilic addition to a carbonyl
Nucleophile attacks a carbonyl ( i.e aldehyde) which pops off the carbonyl bond. Then the O of cabonyl can get protonayed to become OH. Overall, we formed an aldehyde
What are key points on oxygen in the form of "O" ?
O on its own has 2 non-valence electrons and 6 valence electrons It has a high Zeff and high electronegativity O is also a free radical due to unpaired valence electrons
What strength of reducing agent do you use to reduce a carboxylic acid to 1 alcohol and water?
ONLY strong strong: LiAlH4
What strength of reducing agent do you use to reduce an ester to 1 alcohol? aka we split it 2 parts
ONLY strong strong: LiAlH4
We are provided standard reduction potentials for zinc and iodine at 25 degrees celsius. What type of reaction is occurring between I2 and Zn? A. Acid-base (neutralization) B. Precipitate formation C. Oxidation-reduction D. Chelate formation
Oxidation-reduction
this is the method of cleaving alkenes or alkynes using ozone (O3). The result is that carbon-carbon double bonds or triple bonds will be replaced by double bonds with oxygen (i,e aldehyde, ketones)
Ozonolysis
Naming polyatomic ions containing phosphate PO4 3- H2PO4
PO4 3- = phosphate H2PO4- dihydrogen phosphate
Explain the STP volume of 22.4L
PV = nRT V/n = RT/P = [(0.0821)(273K)] / (1atm) = 22.4L/mol
vapor pressure lowering ( Raoult's law)
Pa = XaPa' Pb = XbPb' X us mole fraction of solvent P is vapor pressure Solutions that obey Raoult's law are called ideal solutions
Which of the following substances is most likely to be more soluble in 1.0 M HCl than in 1.0 M NaOH?
Pb ( OH2)
Tell me more about peptide bonds
Peptide bonds - resonance -planar molecular geometry - partial double bond character - NOT very reactive = VERY STABLE, they actually prefer cellular scaffolding
Which of the following reagents would be involved in the first synthetic step to chemically derive an amide from oleic acid? Phosphorous pentachloride Aminobutane Octadecanol 2-aminopentane
Phosphorous pentachloride We want an amide from oleic acid (weak acid). In order to make an amide we need to understand the hierarchy of relative reactivities of carboxylic acid derivatives. Amides are the most stable (least reactive) of the carboxylic acid derivatives because the amino substituent is a very poor leaving group. In order to synthesize amides however, one cannot simply use the amino substituent as a nucleophile; instead amine is a strong base which will prefer to participate in an acid-base neutralization reaction with the acidic hydrogen of the organic acid. First, we need to create an acid chloride (or an acid anhydride) to eliminate the confounding acidic hydrogen. Afterwards, one can proceed with a normal nucleophilic substitution.
The amine in Gabriel synthesis is generated from which reagents
Potassium phthalamide (a protected form of ammonia that prevents multiple alkylations due to the steric hindrance of phthalimide group). AND diethyl bromomalonate
carboxylic acid prefix and suffix
Prefix: carboxy- Suffix: -oic acid
alcohol prefix and suffix
Prefix: hydroxy- Suffix: -ol
Aldehyde prefix and suffix
Prefix: oxo- Suffix: -al
ketone prefix and suffix
Prefix: oxo- or keto- Suffix: -one
What is the mnemonic for priority in stereochemistry?
Priority is "SONCH" like Sanchez: S> O> N> C> H but technically the order is by molecular weight ex: NH3 > COOH > CH3 > H
Purines vs. Pyrimidines
Purines: A, G (2 rings) Pyrimidines: T, C, U (1 ring) UTP = uridine 5 triphosphate which is derived from uracil. Uracil is a pyrimidine and only found in RNA (ribose) G-C bond has 3 H bonds (higher melting temperature) A-T bond has 2 H bonds Vitamin B12 is involved in making PURINES. Therefore vitamin b12 deficiency would direcly affect DNA replication and RNA synthesis
What is the rate law for an SN1 reaction?
Rate = k [substrate] Unimolecular rxn , whose rate determining step is the dissociation of a leaving group from the substrate of the reaction. Because this rate limiting step involves only substrate, the rate law depends only on the concentration of substrate
The rates of diffusion of four drugs were tested: acetazolamide (pKa = 7.2), sulfadiazine (pKa = 6.5), warfarin (pKa = 5.0), and cephalexin (pKa = 3.6). Which drug will have the strongest conjugate base?
The Ka and pka values of acids are inversely related to each other since pka = -log(Ka) and to corresponding Kb and pkb values of their conjugate bases. Thus, the strongest conjugate base will be produced by deprotonating the weakest acid. As pka values decrease, acid strength goes up. Thus, the weakest acid present, has the greatest pka value. You can also do the short cut which is based on pka + pkb = 14. Thus, as pka increases, pkb decreases which indicates a stronger base
Protecting groups like Boc group function by:
The addition of dansyl chloride to comp 1 requires an amine nucleophile to attack the elctrophile sulfur atom in dansyl chloride. Because there are two amines in comp 1, the one bonded to the alpha carbon needs to be protected so it will not react. The Boc group provides steric hindrance to prevent the amino group from acting as a nucleophile
The equation for calculating mean arterial pressure (MAP) is shown. MAP = (2 × diastolic) + systolic3 What is the MAP of a person whose blood pressure is 135/90 mmHg? A. 85 mmHg B. 90 mmHg C. 105 mmHg D. 110 mmHg Solution
The blood pressure reading shows that the diastolic pressure is 90 mmHg and the systolic pressure is 135 mmHg. The calculation is [(2 × 90) + 135]/3, which is 315/3 = 105 mmHg.
Which of the following reasons best explains why it is possible to separate a 1:1 mixture of 1-chlorobutane and 1-butanol by fractional distillation? A. Both 1-chlorobutane and 1-butanol are polar. B. Both 1-chlorobutane and 1-butanol are nonpolar. C. The boiling point of 1-chlorobutane is substantially higher than that of 1-butanol. D. The boiling point of 1-chlorobutane is substantially lower than that of 1-butanol.
The boiling point of 1-chlorobutane is substantially lower than that of 1-butanol. *The fact that 1-chlorobutane will have a boiling point that is substantially lower than that of 1-butanol can be rationalized from chemical principles. The molecules have similar molecular weights, but 1-butanol has a hydroxyl functional group that can participate in hydrogen bonding. Hydrogen bonding is a particularly strong force of intermolecular attraction.
Common ion effect
The common ion effect describes the effect on equilibrium that occurs when a common ion (an ion that is already contained in the solution) is added to a solution. The common ion effect generally decreases solubility of a solute. ex: lets say you have AgCl and you add AgNO3
coordination number
The coordination number is the number of times that molecule binds with the other molecule as in the structure. However, it does not say anything about oxidation state. We know that in the compound [Cu(NH3) 4]^2+ the 4 incidates only the coordination number since it tells us the number of bonds to the copper but does not specify oxidation state since NH3 is neutral
In [Cu(NH3)4]2+, the subscript 4 indicates which of the following? [Cu(H2O)4]2+(aq) + 4NH3(aq) -->[Cu(NH3)4]2+(aq) + 4H2O(l) A. The oxidation number of Cu only B. The coordination number of Cu2+ only C. Both the oxidation number of Cu and the coordination number of Cu2+ D. Neither the oxidation number of Cu nor the coordination number of Cu2+
The coordination number of Cu2+ only Because ammonia is neutral, the number 4 reflects only the number of ammonia molecules that bind to the central Cu2+ cation and does not indicate anything about its oxidation number.
According to the reaction shown below, how much G6P (MW = 260 g/mol) is required to produce 176 g of CO2? Glucose 6-phosphate + NADP → 6-phospho-glucono-1,5-lactone + CO2 + NADPH + H+
The equation shows that 1 molecule of G6P yields 1 molecule of CO2, so there is a 1:1 molar ratio of the two molecules. Thus, 176g of CO2 is 4 moles (molecular mass of 44g), so we also need 4 moles of G6P. 4*260g/mol 1040g
What is the [H3O+] in the solution used in the experiment done at the lowest pH (pH = 6)? A. 0.01 μM B. 0.1 μM C. 1.0 μM D. 100 μM
The lowest pH is 6. Because pH = -log([H3O+]) [H3O+] = 1.0 × 10-6 M or 1.0 μM.
What is the pH of a buffer solution that is 0.2 M in HCO3- and 2 M in H2CO3? (Note: The first pKa of carbonic acid is 6.37.) A. 4.37 B. 5.37 C. 6.37 D. 7.37
The pH of the solution can be calculated using the Henderson-Hasselbach equation: pH = pKa + log([base]/[acid]). Plugging in the values provided in the question gives pH = 6.37 + log(0.2/2) = 5.37.
What are the hybridization states of the carbon atoms involved in the conversion of trans to cis retinal?
The reacting carbon atoms are both central to AX3 systems with 3 bonded atoms and no lone pairs. The preferred geometry for such a system is trigonal planar and the hybridization scheme that facilitates this geometry is sp2.
What are the hybridization states of the carbon atoms involved in the conversion of trans to cis retinal? A. sp B. sp2 C. sp3 D. sp3d
The reacting carbon atoms are both central to AX3 systems with 3 bonded atoms and no lone pairs. The preferred geometry for such a system is trigonal planar and the hybridization scheme that facilitates this geometry is sp2. double bonds = sp2
instructions for line to fischer
This is how we can convert a line structure version into a Fischer projection: 1) first determine the R/S config of the line structure group #4 is always an H and it must be in the back (dashed); if not, then you'll switch its priority at the end 2) now start the fischer projection by puttine COOH on top ALWAYS, CH3 (aka attachment) on the bottom 3) the left and right side of the Fischer will be NH2 and H but just guess wherever for these 4) check R/S configur for Fischer projection. Since Fischer never put the H on the bottom position (dashed) then we always have to switch the configuration. So let's say I found that my Fischer had R config. well since H is on left/right and we really want it on the bottom then we must switch to S (this last config MUST match the line structure config). If it does not then switch the H to the other side (left/right)
Explain pH at equivalence point for: Strong Acid Weak Acid Weak Base
This is the point at which all "acid has been deprotonated" or "all titrant/reactant has been used up" Strong Acid, pH =7 Weak Acid, [hella H+], pH<7 Weak Base, [little H+], pH >7
If a molecule structure has a carboxylic and amine group then pH of 7 the charges of each would be:
amine is NH2 (neutral) Carboxylic acid is O- (-1 charge)
vitamin E is considered
an antioxidant
electronegativity
the tendency of an atom to attract electrons within a bond
Which of the following is the overall reaction for the decomposition of H2O2 that is shown in reactions 3 and 4? Rxn 3: H2O2 + I- --> IO- + H20 Rxn 4: H2O2 + IO- --> H20 + O2 + I- A. 2H2O2(aq) + IO−(aq) → 2H2O(l) + I−(aq) + O2(g) B. 2H2O2(aq) + 2I−(aq) → 2H2O(l) + I2(g) + O2(g) C. H2O2(aq) → H2O(l) + O2(g) D. 2H2O2(aq) → 2H2O(l) + O2(g)
This response depicts the net sum of reactions 3 and 4: 2H2O2(aq) → 2H2O(l) + O2(g) do not include any spectator ions
UV-Vis spectroscopy
This technique detects conjugated pi systems and metal-to-ligand charge transfer species. For example, a peak corresponding to a charge transfer can be shown. red shift- more resonance means more red complementary wavelength- wavelength absorbed is opposite the one that is perceived (*Christmas, Portal, Lakers*) red is 700 nm, violet is 300 nm
Why was it important that the cuvettes containing the glucose oxidase and the blood sample were identical in terms of optical properties? A. To enable the comparison of the absorption spectra B. To reduce the absorption in the glass walls C. To decrease the uncertainty in the wavelength D. To increase the absorption in the solutions
To enable the comparison of the absorption spectra *The identical optical properties of the cuvettes ensure that the absorbed radiation is due only to the presence of glucose in the blood and not due to the difference in the absorption features of the walls.
Which of the following strategies would be suitable for converting TX-100 (an alcohol) into an anionic surfactant at physiological pH? Reacting TX-100 with a weak base Adding PCC to TX-100 in a non-aqueous solution Treatment with KMnO4 Titrating TX-100 with concentrated sulfuric acid
Treatment with KMnO4 TX-100 is an alcohol therefore if we treat with KMNO4 then we oxidize to carb acids which are semi acidic and will dissociate at physiological pH since they have a pka less than 7. This reaction would convert TX-100 into an anion since it deprotonates the H
Addition of which sugar to a solution in the presence of BEnedict's reagent would NOT result in the formation of a red precipitate?
Trehalose is a non-reducing sugar because it has the cyclic O right next to a carbon that has an OH therefor in its fischer structure it will have a carboxylic acid ( nonreducing sugar , aka cannot be oxidized) Trehalose is a non-reducing sugar because of its chemical structure, in which the anomeric carbons of both rings are participating in glycosidic linkages. In order to be reducing sugar, a ring must contain hemiacetal carbons which can revert to the open chain form in which they are aldehydes or alpha ketones, which can be reduced. In order to become reduced, a ketone would need to tautomerize to an aldehyde structure and become reduced.
Given that the passage states that HRP acts on aromatic amines and phenols, then the side chain of which amino acid is most likely to be a substrate for HRP? A. Lys B. Leu C. Tyr D. Gln
Tyr Tyrosine has the only side chain that is a phenol
Of the events listed, which occurs first during action potential generation? A. Voltage-gated sodium channels open at the axon hillock. B. Hyperpolarization stimulates the opening of ligand-gated potassium channels. C. Graded potentials propagate along the axon. D. Calcium influx stimulates vesicle fusion and release of neurotransmitter.
Voltage-gated sodium channels open at the axon hillock. *When threshold is met at the axon hillock, voltage-gated sodium channels open, generating an action potential. Calcium influx and release of neurotransmitter does not occur until action potentials arrive at axon terminals. then, Graded potentials propagate along the cell body and dendrites . Voltage-gated (not ligand-gated) potassium channels open in response to depolarization, not hyperpolarization.
The density of a human body can be calculated from its weight in air, Wair, and its weight while submersed in water, Ww. The density of a human body is proportional to:
Wair = mg *always since gravity is simply mg pulling us down to earth Ww (aka us in water) *water will push us out (repel us partly) so Wair-Ww * we know this repelling by water is called buoyancy (Fb) * so we can write Fb = mg-Ww Fb = Wair - Ww Since we know specific gravity is always p of object /p H20 then we can plug in our previously found equations: Wair /(Wair - Ww) again this is the same as saying mg/(mg-Fbuoyant)
Which of the following pairs of solvents would form two separate layers when mixed together in a shaker flask and then allowed to settle? Formic acid and ether Acetone and toluene Methanol and water Water and octane
Water and octane
How much volume does a mole of liquid water occupy?
Water weighs 18g/mol so a mole of water would weigh 18 grams. Using density of 1g/ml, the water would occupy a volume of 18ml
Compare water to water bond vs water to oil bond
Water-to-water bonds: strong hydrophilic bonds that can create hydrogen bonds Water-to-oil bond: Weaker because they are mostly van der waal forces (i.e dipole dipole type). Aka a small, temporary dipole is induced in molecules of oil by the permanent dipole of water, resulting in a weaker attraction between the molecules
What is the concentration of Calcium ion in saturated solution of CaCO3.
Write a rxn: CaCO3 (solid!!!!) --> Ca^2+ + CO3 2-) we are told CaCO3 is a solid in the passage therefore we can leave it out Ksp = products / reactants Ksp = (ca2+) ( CO3 2-) 4.9 * 10^ -9 = (ca2+) ( CO3 2-) 4.9 * 10^ -9 = x^2 49 * 10^-10 = x^2 x = 7 * 10 ^ -5 ex2: Ksp equation rules 1. first dissociate your reaction so that you can see break it down into parts i.e Ca3(PO3)2 ---> 3 Calcium + 2 phosphates 2. Ksp = [3 Ca]^3 [2PO]^2 = [3x]^3 [2x]^2 = 27x^3 * 4x^2 = 108 x^5
In the case of a buffer solution, the titration is ____ to the equivalence point when a pH is achieved that is near the pka value of the buffer's acid.
close
ubiquinone is also called _______ and is a vital electron carrier associated with complexes 1,2,3 of ETC
coenzyme Q
Oxygen, like all gases, is more soluble in _____ water therefore _____ water would lower the solubility
cold, warm
How to draw a lewis structure for XeF4?
XeF4 is a compound that has two lone pair so it really has 6 substitutents. We know this because Xe has eight valence electrons. It gets 4 of these eight electrons from the two lone pairs and four from the bonds - one electron from each bond. Two lone pairs and four bonds gives us six total regions of electron density. So we need six hybrid orbitals to hold those electrons: s, p, p, p, d, d therefore sp3d2 **You can also calculate this by drawing out the Leqis structure: We know that 8 electrons (valence) must come from Xe atom. Also 7 electrons must come from F atomsdue to their valence number. Therefore 8 + 7(4) = 8 + 28 = 36 electrons If we draw XeF4 with Xe as the center atom and single bonds between the Xe atom and each F atom produces a structure with only 32 electrons, so we must add two lone pairs to the central Xe atom
Given equation: hint: we are working with a weak acid H2PO4- ---> HPO4 2- + H+ (5M) (0.5M) pka = 6.8 for reaction urine pH range is 4.5 to 8.0 A phosphate buffer system is made according to reaction 1 using 5 M H2PO4- and 0.5 M HPO4 2-. Will the pH of this system fall within the pH range for urine?
YEs, pH = 5.8 BIG HINT: when given pka,.... USE Henderson-Hasselbalch eq ph = pka + A-/HA = 6.8 + log ( 0.5/5) = 5.8 this value is between the urine pH range
The ionic form of which metal atom is NOT likely to be found in the pocket of a catalytically active DNA polymerase? A. Zn B. Fe C. Mg D. Na
You can see that the image shows M2+ in the center therefore we can mimic this with ions that have the 2+ charge (Fe2+, Zn2+, Mg2+). Sodium does not readily form a divalent cation, essential for DNA polymerase catalytic activity as shown in Figure 1.
Anhydride + phenylethylamine --> amide and carboxylic acid . Which aqueous solution can be used to separate the amide and the carboxylic acid products of this reaction in an extraction?
You can use NaHCO3 which is a weak base. This is because you are working with amide and carboxylic acid. A carboxylic acid has an OH that can easily be deprotonated by an Na in solution. Therefore NaHCO3 deprotonates carb acid leading to a carboxylate anion which can be sequestered into the aqueous layer. The amide remains in the organic layer
What is the total number of sp2-hybridized carbon atoms present in a molecule?
You count all the CARBONS next to double bonds including double bond in carbonyl
What is the charge relationship between C and N in C-N bond?
You need to be able to interpret what is in reactants and how that changes inthe product form. We can see from rxn 5-6 Strecker that the reactants are CN with water. The products form COOH which means the water combined with the C, and the N was separated out. Therefore we went from C-N bonds to C-O bonds. This must be bc the lone pair on the water attacked the C. We know it attacks the C in CN bc the N is pulling electron density away from C which makes C positive and vulnerable to being attacked. Now lets says you add another electron withdrawing group to CN structure, then this would pull much more electron density from C which makes C much more positive. Now C is MORE LIKELY TO BE ATTACKED = MORE LIKELY TO FORM MORE CARBOXYLIC ACID
Why does solution polarity matter for compounds in solution?
You want to make sure that the compounds don't react with the solution (aka the environment); instead we just want it to combine with the other solute
What is stronger: intramolecular bonds or intermolecular bonds?
You would assume that a structure will be stronger when it has INTERmolecular forces rather than just intramolecular forces. you can understand this in the sense that you can try to be strong within yourself but if you don't have strong bonds with others like your network then it will be hard for you to find emotional, physical, mental stability. In addition, compound is stronger if it has actual disulfide bonds (S-S) > SH bonds
copper II electron configuration
[Ar]3d^7 This is because copper is a transition metal which means that the 4s is removed completely since it has a higher energy therefore all the electrons are instead placed on the 3d
Alkyl halides typically undergo SN1 reactions. If a vinyl halide were to undergo substitution, the reaction mechanism would probably be most similar to the substitution of: (aryl or alkyl halide) and why?
an aryl halide ( an aromatic containing a halide) because the carbon-halide bond in vinyl halides has a more s character than in alkyl halides Bonds composed of atoms with more s character (sp2 > sp3) are stronger, and thus require more Energy to break. In vinyl halide, the carbon bonded to the halogen in an alkyl halide is sp3 hybridized. Therefore, a vinyl halide is much less likely to undergo ionization during an SN1-like mechanism. Additionally, the electron withdrawing effect of a vinyl halide double bond decreases the stability of the carbocation which forms during an SN1 rxn. Overall, these effects increase the relative favorability of an eleimination addition rxn over an SN1
A man is accidentally exposed to a toxin which binds irreversibly and noncompetitively to pyruvate dehydrogenase. A likely consequence of this ingestion is:
a decrease in the level of Krebs cycle activity within the exposed cells. The pyruvate dehydrogenase complex converts pyruvate (a three-carbon molecule that is produced by glycolysis) into acetyl-CoA, a two-carbon molecule that is fed into the citric acid cycle for further metabolism. As the name implies, the pyruvate dehydrogenase complex is indeed a complicated structure composed of multiple molecules. It contains three distinct enzymes that are physically linked with each other (pyruvate dehydrogenase being the most important for the MCAT, but pyruvate dehydrogenase is linked to dihydrolipoyl transacetylase and dihydrolipoyl dehydrogenase, which assist in some of the maneuvering involved with the coenzymes). The complex also requires the action of no fewer than five coenzymes: thiamine pyrophosphate (TPP), FAD, NAD, CoA, and lipoate. It is useful to note that several of them (thiamine, FAD, NAD, and CoA) have components derived from B vitamins. The conversion of pyruvate to acetyl-CoA is accompanied by the production of 1 molecule of NADH, which can eventually enter the electron transport chain to generate ATP, and 1 molecule of carbon dioxide. In eukaryotes, the pyruvate dehydrogenase complex is located within the mitochondrial matrix.
mass spectrometry
a destructive technique that monitors a charge/radius ratio of fragments ; will have little use if there are structural similarities before and after
Equilibrium in a graph is represented by:
a horizontal line since that shows constant concentration needed aka forward and reverse reactions are functioning at same rate
TITRATION
a procedure used to determine the molarity of an acid or base by reacting a known volume of a solution of unknown concentration with a known volume of a solution of known concentration. The half-equivalence pt defines pH = pka.
What is the pH of a 0.10 M aqueous solution of acetylsalicylic acid (pka = 3.5?
acetylsalicylic is aspirin. Aspirin has pka = 3.5. Since we know this is an acid and acids like to have Hs and be protonated then ph<pka. Thus elimate any values above 3.5. At ph = 3.5, the concentration of weak acid and conjugate base are equal (buffer) so this cannot be the pka either. At pH = 1 for an acid whose concentration is 0.10M, this would require complete dissociation OR log (10^-10 = - 1, note: only works if referring to acid outcome
The researchers want to use narrow-spectrum LEDs to make their lamp more efficient. Assuming that the energy of a photon absorbed by porfirmer is transferred without loss to oxygen, what wavelength of light should the researchers select? (Note: Planck's constant is 6.626 x 10-34 J∙s) Given: energy value as 94.kJ/mol
again a question that you needed extra passage info from. I need to start with finding energy in joules. We are given an energy value as 94.kJ/mol which we need in just joules. Therefore multiply by Avogadros number to get joules. Now you can easily use this in the E= hc/wavelength so get wavelength
What is the net charge of the peptide Arg-Ala-Phe-Leu at pH 8?
all aa are neutral except arginine which is basic and has a charge of +1 at pH of 8 since its pka is like 10 ph<pka therefore we have hella H+ in solution so we expect NH3 to be protonated and have that extra + that we calculate
Acylation reactions between anhydrides and amines generate ___ and _____
amides and carboxylic acids
Which atom is most likely involved in the coordination of calcium ions found in HRP? A. Hydrogen B. Carbon C. Nitrogen D. Oxygen
an atom must be a Lewis base to coordinate to calcium ions, and oxygen is the only Lewis basic atom present in the side chains or backbones of the listed amino acids that has either a partially negative charge (in the peptide backbone or Ser side chain) or a negative charge (in the Asp side chain). The only other Lewis basic atom present is nitrogen (distractor C), which has a partially positive chain in the peptide backbone due to resonance, and is thus less likely to coordinate calcium ions.
Deviations of PV = nRT due to pressure
as the pressure of a gas increases, the particles are pushed closer and closer together. At moderate high pressure, a gas's volume is less than would be predicted by ideal gas law due to intermolecular attraction
Deviations of PV= nRT due to temperature
as the temp of a gas decreases, the average velocity of the gas molecules decreases and the attractive intermolecular forces become increasingly significant. Increased intermolecular attraction causes the gas to have a smaller volume than would be predicted. At extremely low temp, the volume of the gas particles themselves causes the gas to have a larger volume than would be predicted If Temp decreases hella = volume increase sonly slightly
What is the concentration of hydroxide ion for the solutions with the highest pH (10) that was studied? A. 10-10 B. 10-6 C. 10- 4 D. 10-2
at the highest pH tested (10) the [H3O+] is 10-10 M. This means that [OH-] is 10-4 M, because [H3O+] × [OH-] = 10-14 for aqueous solutions at 25°C.
affinity chromatography
beads are coated w/ a receptor that binds the protein of interest (high affinity) - protein is retained in column - can be eluted by washing the column w/ a free receptor that competes w/ the bead bound receptor & frees protein -eluted also by changing pH or salinity levels to disrupt bond b/w ligand & protein; or use detergent
What is the structure shape of water:
bent
Hydrogen bond
between a hydrogen bond donor(an H connected to O, N, F) and hydrogen bond acceptor(O,N, F)
antagonist ______ the biochemical function of the protein it binds to.
blocks For example, blocking the catalytic activity of HIV protease towards its substrate
Half reaction at anode is LiC6 --> Li+ + e- + C6 Total net reaction is LiC6 + CoO2 --> LiCoQ2 + C6 What is the half reaction at the cathode?
cathode is the location for reductions so we know electrons will appear in the reactants side REducx = REactants side At cathode side: CoO2 + Li+e- --> LiCoO2
combustion reaction
ch4 + 2O2 --> CO2 + 2H20. Note that the hydrocarbon (CH4) can be in any other form as well (c2h6, c3h8, c4h10)
beta plus decay
change proton to neutron ( so atomic number decreases since we basically lost a proton) however mass stays the same bc the proton was just converted to a neutron and mass = neutron + proton) also emits a positron ** top number is mass ** bottom number is atomic number
farnesyl pyrophosphate In the human body, two FPP molecules are combined in a reaction that directly leads to which class of compounds?
cholesterol
What is the primary process responsible for the loss of latent heat and entropy from the ocean at the air-sea interface? Precipitation Condensation Evaporation Melting
evaporation a negative latent heat implies that the phase change that is occurring is consuming energy. Therefore, the phase change that is occurring is melting, evaporation or sublimation. The fact that this process is occurring at the air sea interface means that the phase change must involve the gas phase. That fact rules out melting. Since sublimation is not an option, this leaves evaporation. It makes sense that evaporation, the ocean is losing entropy at the expense of the atmosphere which is gaining gas particles
Absorption of UV light always results in _______ of bound electrons
excitation
separation of amides and carb acids can be done by what technique?
extraction Since we can deprotonate carboxylic acid to have a negative charge, it will be more soluble in water than the aldehyde group. Therefore, an extraction with a dilute weak base such as NaHCO3 woudl separate these two molecules.
In its lowest-energy electron configuration, zinc has a: A. filled 3d energy level and a filled 4s energy level. B. half-filled 3d energy level and a filled 4s energy level. C. filled 3d energy level and a half-filled 4s energy level. D. half-filled 3d energy level and a half-filled 4s energy level.
filled 3d energy level and a filled 4s energy level. * although zinc is a transition metal (& we generally want to follow the rule that transition metals do not have 4s), it is on the cusp meaning it needs 42 since all of our 3d is already full
Sn1 reaction is also called a ___ reaction
first order An SN1 reaction is a unimolecular reaction, whose rate determining step is the dissociation of a leaving group from the substrate of the reaction, forming a carbocation. Because this rate limiting step involves only the substrate, it is first order
how do you determine the pka from a titration curve?
first plateau(horizontal region) = region where H from carboxylic acid is removed; Mnemonic: "Ese plato pika"
Anionic surfactants most likely reduce the rate of nucleophilic reactions of hydroxide ion with neutral compounds by: preferentially interacting with the nucleophile, thereby inhibiting it from reacting with the substrate. acting as a nucleophile and undergoing undesired cross-reactions with the substrate. forming a negatively charged surfactant-substrate complex that repels the nucleophile. more readily forming micelles that sequester the substrate from the nucleophile.
forming a negatively charged surfactant-substrate complex that repels the nucleophile. Cationic surfactants increase the reaction rate (according to passage) Therefor epositively-charged surfactant-substrate complexes and the hydroxide ion promote the reaction.
nonbonded strain
from interactions with substituents on nonadjacent carbon. In cyclohexane, the largets substituent usually takes equatorial position to reduce nonbonded strain ex: Van der waal repulsions
triacylglycerol structure
glycerol and 3 fatty acids
which amino acid does not have optical activity?
glycine = NO CHIRAL CENTER = NO OPTICAL ACTIVITY
how do you determine the pH of isoelectric point for glycine from a titration curve with NaOH?
glycine is a zwitterion so found from pI = 1/2(pka1+ pka2) where pka1 (amine terminus) and pka2(carboxylic terminus); pkas are at the equivalence regions on titration curve so 1/2(2.5)(9.5) The isoelectric point is the pH at which the net charge of the amino acid is zero, or when the carboxylate is deprotonated (having a negative charge) but the amine group is still protonated (in its ammonium form with a positive charge). In other words, glycine is in its zwitterion form. This occurs at the first equivalence point since glycine has lost only one H so it can gain/lose H. The pH corresponding with the middle of the first sharp rise in pH, at 15ml of added NaOH solution, is the isoelectric point. Hence, the estimated pH of the isoelectric point is 6.
What reagent is needed for intramolecular formation of cyclic anhydride?
heat to convert ortho-phthalic acid --> phthalic anhydride + water
higher atomic weight USUALLY indicates _____ shielding
higher atomic weight USUALLY indicates better shielding - higher density indicates better shielding too
Photons in IV region have enough energy to excite certain electrons to a ____ energy state. After excitation, the electron loses some of its energy as heat. The remaining energy is emitted as a photon with a ____ wavelength than the one that was absorbed; aka now with ess energy
higher, higher
melting point factors
highest melting point - usually increased with size of the molecule - usually increased by more dispersion forces - has strong dipole dipole interactions and hydrogen bonding = AKA IT IS HARD TO MELT BC IT SO BULKY ex: valine > ethanol, butane, glycine
Equivalent hydrogens
hydrogens that surround the same atom and specifically come in pairs (like hydrogens opposite of the same atom. However this number will sometimes be different from the amount of peaks in the NMR. For example, ethanol is 2 carbons connected to an OH. therefore it will have three different types of Hydrogens but only 2 of these are equivalent hydrigens because they have pairs unlike the OH. However we will still see 3 peaks in the NMR.
Which bond found in a protein depicts the interaction that most greatly contributes to protein stability?
hydrophobic interactions are a type of stabilizing interaction between nonpolar molecules ( common non-polar organic molecules include aromatic rings, alkyl chains, etc). The passage states that hydrophobic interactions, like the interaction between two nonpolar aromatic rings, produce the greatest contribution to protein stability
If you further oxidize a quinone, then it is possible to form a _________
hydroxyquinone
When a 0.1 M H2SO4 solution is added to pulverized blackboard chalk, the following reaction takes place. CaCO3(s) + H2SO4(aq) CaSO4(s) + CO2(g) + H2O(l) At 25°C, the reaction is spontaneous and has: A. negative ΔG° and positive ΔS°. B. negative ΔG° and negative ΔS°. C. positive ΔG° and negative ΔS°. D. positive ΔG° and positive ΔS°.
negative ΔG° and positive ΔS°. Spontaneous reactions must have a negative ΔG°, and reactions that create gaseous products from solids and liquids must have a positive ΔS°.
Which is the strongest acid? CHeOH2+ CF3COOH NH3 NH4+
i missed this bc I didn't compare conjugate acids to their bases B) CHeOH2+ is the most acidic bc if if remove an H to get its conjugate base, we see that it is actually very stable since it is neutral. This neutral state is actually preferred. AND we know that things that RELEASE Hs are ACIDS A) CF3COOH: we cannot right off the bat that Carboxylic acids will always be the most acidic. In fact, this is a weak acid bc it is more stable with an H than removing the H. If this is a weak acid then CF3COO- is a strong base D) NH3 is a SUPER STRONG BASE so NH2 will be a weak acid C) NH4+ must be a weak acid bc its conj base (NH3) is a strong base
Racemic mixtures and meso compounds are optically _______
inactive
Reducing agents
include Na, Mg, Al, Zn, which have low electronegativities and ionization energies, like NaH, CaH2, LiAlH4, NaBH4 because they contain the H- ion DIBAL is another reducing agent that can reduce carboxylic acid to an aldehyde when applied at a precise 1:1 ratio. Both mild and strong reducing agents can reduce aldehydes and ketones to primary and secondary alcohols
If the quantity of gas remains unchanged while its temperature increases, the volume of the gas will:
increase if pressure remains constant T and V are directly proportional ex) a balloon out in the sun will inflate more
N2 + 3H2 --> 2NH3 ( exothermic) what shifts it right?
increase in pressure only
a leak in a distillation flask will cause temp to _______ and vapor pressure to _____therefore surface area _____ and BP of both liquids _____
increased for all
Magnitude of the dipole moment ______ as the difference in electronegativity between the two atoms in the bond increases
increases
if you grind a heterogeneous catalyst, this ______ the amount of catalyst available to the reaction and therefore increases its rate
increases aka more surface area!
Atomic radius
increases down and to the left on th periodic table only one that goes against the other common rules
As atomic number increases in a horizontal row of the periodic table, ionization energy generally:
increases, because of increasing effective nuclear charge Increase is to the right and upward
pressure and volume relationship
inverse
thioether
is an S between two carbons disulfide is a two Ss with carbons on both ends: R-S-S-R thioether/ sulfide R-S-R disulfide: R - S - S - R
Heisenberg uncertainty principle
it is impossible to determine with perfect accuracy the momentum and the position of an electron simultaneously since it is constantly moving
Air is bubbled through distilled water. The solution will have a pH:
less than 7, because carbon dioxide undergoes hydrolysis. imagine that air bubbles are allowed to enter water then that means that the co2 from air will become hydrolyzed since water will disturb it. As a result, carbonic acid is produced which is a weak acid that produces a solution whose pH is less than the pH of water H2O (aq) + CO2 (g) ⇌ H2CO3 (aq) ⇌ H+ (aq) + HCO3− (aq) Carbonic acid (H2CO3) has the conjugate base of HCO3−. Buffers work because the concentrations of the weak acid and its salt are large compared to the number of protons or hydroxide ions added or removed. When protons are added to the solution from an external source, some of the bicarbonate in the buffer is converted to carbonic acid, using up the protons added; when hydroxide ions are added to the solution, protons are dissociated from some of the carbonic acid in the buffer, converting it to bicarbonate and replacing the protons lost.
Distillation separates _______- based on boiling point How many diff types are there?
liquids based on boiling point, which depends on intermolecular forces. 1) simple 2) fractional 3) vacuum
Magnetic quantum number m with little l
magnetic quantum number (ml) describes the spatial orientation of the orbital in question within its subshell. Potential values of ml range from -l to +l. Since each orbital can hold a maximum of two electrons, this means that an s subshell can contain up to two electrons, a p subshell can hold up to six electrons, a d subshell can contain up to 10, and an f subshell can hold up to 14. range is between l and -l s orbital is sphere shaped p orbital is ear-shaped
Catalytic converters are involved in converting different gases:
methane to CO2 and water carbon monoxide to carbon dioxide nitric oxide to nitrogen THEY DO NOT involve sulfurs This response depicts a chemical transformation (SO3 → SO2 + H2O) that is NOT catalyzed by an automobile's catalytic converter.
The hemiacetal below is treated with 18O-labeled methanol (CH3O*H) and acid. Where will the label appear in the products?
methanol is CH3OH so the OCH3 part will attach to the molecule so that O in the molecule has the label
Electrophoresis
method of separating serum proteins by SIZE and/or CHARGE
Which of the following compounds will have the highest retention time when run in a gas-liquid chromatography chamber? methylcyclohexane (BP= 101) Hexane (BP = 68) Methylene chloride (BP = 39.6) heptane ( 98.4)
methyl cyclohexane Retention time is the time it takes for the sample to reach the detector. The higher the boiling point temp, the more time the compound will spend at the beginning of the chamber waiting to get volatilized. Therefore, the compound with the highest boiling point will have highest retention time.
High Performance Liquid Chromatography (HPLC)
mobile: nonpolar solvent stationary: small column with concentration gradient - similar to column chromatography but uses sophisticated computer-mediated colvent and temperature gradients - is used if the sample size is small or if forces such as capillary action will affect results - formerly "high pressure"
Which pair of formulas represents the empirical and molecular formulas, respectively, of caffeine? ( given that the structure shows C8H10N4O2
molecular: C8H10N4O2 empirical: C4H5N2O
Limestone does NOT decompose when heated to 900 K because, at 900 K, ΔH is: A. positive and less than TΔS. B. positive and greater than TΔS. C. negative and less than TΔS. D. negative and greater than TΔS.
positive and greater than TΔS. *The reaction does not occur (is not spontaneous). This indicates that ΔG = ΔH - TΔS > 0. From inspection of the reaction, it can be concluded that ΔS > 0 (a gas evolves). Consequently, ΔH > TΔS explains why the reaction does not occur. Just imagine G = H-TS IF we want G to be positive then + G = H-TS then H and TS must be positive so that we have a reaction that is positive (aka not occurring; nonspontanoues)
Heat absorbed or released in a given process equation
q = MC*change in T m: mass c: specific heat T: temp
How is rate law different from law of mass action(aka equilibrium constant)?
rate law: determined experimentally only includes reactants equilibrium constant: Kc = products/ reactants * liquids and solids are excluded because they are essentially constant * can be affected by number of moles added or temp changes to each side
if reactants dont have chirality, then how does a product have a chiral center?
reactants are not chiral and solvents don't participate in the reaction. And the reactants are chiral so they should give a racemic mixture, but they did not. So chirality came from enzyme in the reaction. I got it right by mere process of elimination
how is equilibrium constant different from reaction quotient?
reaction quotient describes the products/reactants once a reaction commences so it refers to a specific moment in time since reaction is now always changing
Cathode is the site of
reduction
Quinone to Hydroquinone indicates a __________ rxn
reduction
Compound 3 is prepared from Compound 2 (Figure 2) by: A. reduction of the ketone and lactonization of the gamma-hydroxyester. B. hydrolysis of one ester and formation of an acetal from the ketoacid. C. reduction of one ester and formation of an acetal from the gamma-hydroxyketone. D. reduction of one ester and the ketone followed by dehydration to a ketoether.
reduction of the ketone and lactonization of the gamma-hydroxyester. *First, NaBH4 reduces the ketone to a secondary alcohol, the gamma-hydroxyester intermediate. Secondly, the alcohol group in this intermediate then reacts as a nucleophile with the carbonyl in the ethyl ester in the same molecule, forming a new ester by displacing C2H5OH as a leaving group. This cyclic ester is called a lactone, and the intramolecular transesterification yielding this lactone is called lactonization.
Orbital geometry
refers to electron domain geometry so count the bonds AND ELECTRONS. It refers to like C in CH4 or N in NH3
Principle quantum number n refers to
refers to the shell number which is denoted by the period number the higher the n value = the higher the energy level and radius of the electron's orbit. the max number of electrons in energy level n is 2n^2 The first quantum number is the principal quantum number (n). It denotes the energy level of the electron, and can take any integer value (−1). Higher principal quantum numbers (for example, n = 2 rather than n = 1) have greater energy and are farther from the nucleus. The principal quantum number relates to the row of the periodic table in which the element in question is found.
When a battery discharges, the half reaction at the anode _____ electrons
releases aka loses electrons (oxidation) anode: site of oxidation cathode: site of reduction
size exclusion chromatography
relies on porous beads; larger molecules elute first because they are not trapped in small pores
The pi electrons can be delocalized through p orbitals, creating an extended network of conjugated pi bonds known as _____ stabilization
resonance
If we add HCl to a reactants side that has NH3 then we will shift the equation to the _____-
right NH3 will be converted to NH4 since there are so many H+ in solution we would expect low levels of NH3 so in order to increase ammonia we can now shift back to the reactants side in recovery
Stereoisomers
same connectivity, different spatial orientation this is determined by the number of stereocenters placed in the equation: 2^n
Which type of halide (1,2,3) could participate in an SN1 reaction?
secondary and tertiary
Gas Chromatography
separate vaporizable compounds separate it into peaks. The first peak that will show is the most nonpolar (many carbons which indicates that it has only london dispersion forces for intermolecular attractions). These attractions are actually the most volatile of the intermolecular forces. mobile phase: inert gas stationary phase: crushed metal or polymer
extraction the organic layer is usually ____ aqueous layer is usually _____
separates dissolved substances based on differential solubility in aqueous vs. organic solvents the organic layer is usually nonpolar and less dense aqueous layer is usually polar and more dense so at the bottom
Recrystallization
separates solids based on differential solubility in varying temps
The equilibrium BaCrO4(s) Ba2+(aq) + CrO42-(aq) exists in a saturated aqueous solution of BaCrO4. Dissolution of Na2CrO4 in a saturated aqueous BaCrO4 solution would: A. have no effect on the position of this equilibrium. B. shift this equilibrium left. C. shift this equilibrium right. D. shift this equilibrium first right and then left.
shift this equilibrium left. Dissolution of Na2CrO4 would introduce the common ion, CrO42-, which would reduce the solubility of BaCrO4 due to the common ion effect.
Cooperative binding is shown as _______-shaped graphs
sigmoidal
sigma bond is formed at a ___
single bond—consisting of two electrons—between two atoms will form a sigma (σ) bond
Given that the "the ligands(aka like the protein that binds) tend to be mainly hydrophobic with anionic or electronegative features" then the Sites I and II (location where ligand binds) are most likely lined with the side chains of which amino acids?
sites must be hydrophobic and cationic( +) to be attracted so amino acids like arginine and leucine
Weak acids will have ionization constants that are very _______
small between 0-1 but closer to zero
pressure and temp graph
solid is on the left side, liquid is in the middle, and gas is in the bottom right (base region) the middle intersection is the triple point the far off point is the critical point where liquid and gas merge into a single phase
gases are more ______ at colder temps so we would have more oxygen dissolving which could feed iron-precipitating bacteria effectively
soluble
Blue litmus is used when
solution is alkaline
Why would kidney stones given that they are composed of CaC2O4?
some kidney stones will form because precipitation forms which happens when the reaction quotient (Q) which is the solubility at a specific time, exceeds the equilibrium constant (Ksp). The reaction quotient for CaC2O4 (s) --> [Ca2+] + [C2O4] is Q = [Ca2+] + [C2O4] does NOT include solids Q> Ksp thus precipitation forms
southern, northerm , western
southern: DNA western: protein/genes; uses Ab to detect proteins; to analyze Postranslational modification of proteins Northern: RNA Steps: 1) transfer fragments from gel to nitrocellulose paper 2) add radiolabeled probe (DNA) 3) hybridization to complimentary DNA sequence 4) film to visualize
octahedral is what kind of s and p combination?
sp3d2 ( 90,180) ex: SF6 Octahedral compounds have 6 sigma bonds and no stereochemically active lone pairs. According to valence bond theory, the central atom requires the hybridization of six atomic orbitals s, p, p, p, d, d 6 regions of electron density Octahedral geometry is such as the case of SF6 which minimizes the repulsive interactions of the bonding domain electrons
neutralization reaction
specific double-bond displacement reaction that occur when an acid reacts with a base to produce a solution of a salt ( and usually water) HCl + NaOH --> NaCl + H20
Spin quantum number m with little s
spin quantum number (ms) describes the spin orientation of the electron, which relates to its angular momentum. The two possible spin orientations are ms = −1/2 and ms = +1/2. Two electrons in the same orbital (and thus with the same ml value) are said to be paired and must have opposite spin ( aka like its charge) range is -1/2 or +1/2
Gievn that the value of the formation constant of [Cu(NH3)4]2+ is 5.6 1011 at 25°C. At 25°C, the formation of [Cu(NH3)4]2+ according to Equation 1 is most likely a: Equation 1: [Cu(H2O)4]2+(aq) + 4NH3(aq) -->[Cu(NH3)4]2+(aq) + 4H2O(l) A. spontaneous process with positive ΔG°. B. spontaneous process with negative ΔG°. C. nonspontaneous process with positive ΔG°. D. nonspontaneous process with negative ΔG°.
spontaneous process with negative ΔG°. the equilibrium constant for the reaction is very large (much greater than 1). This necessarily means that ΔG° is negative and the reaction is spontaneous.
Spontaneous means that the reaction _______ while nonspontaneous means the reaction ______
spontanous = rxn occurs. G = - NONspon: does NOT occur. G = +
Let's say that you have 7.15g of Na2CO3*10H20 and we want to find how many Na ions there are. How do we do that?
start with what you are given 7.15g * (1mol/286.4g)*(2)*(6.02*10^23 ions/ 1mol) = 3.01*10^22 ions
state function vs non-state function
state: depend on initial and final only ex: pressure, density, temp, volume, enthalpy, internal energy, free energy, entropy non-state: work, heat
Beads in chromatography are _________. What does stationary mean?
stationary Stationary means that it has very strong hydrogen bonds and therefore will hold on tight to the solute that is most similar to itself that can hydrogen bond. As a result, the molecules with strong or more hydrogen bonds, will migrate more slowly.
The rate of substitution for 2 pentanol is less than for 1 pentanol because there is more ________ at the 2 position of the 2 pentanol.
steric hindrance *there is more steric hindrance at the 2-position of 2-pentanol than at the 1-position of 1-pentanol.
Angle strain
stretch or compress angles away from normal size
Amide hydrolysis requires what reagents?
strong acid OR strong base and heat
acetic acid structure
structure of carbonyl with a methyl and an OH
Cis-trans
subtype of diastereomers in which groups differ in position about an immovable bone (such as a double bond or in a cycloalkane)
Which of the following describes the orbital geometry of an sp3 hybridized atom?
tetrahedral ( 109.5) ex: CH4 4 regions of electron density
in the formation of a peptide bond, which terminal attacks which?
the amino terminus attacks the carboxyl terminus in an amino acid linkage. the amino terminus attacks the carboxyl terminus in an amino acid linkage. The amino would attack in this case because it is NH2 while the carboxyl terminus is an OH. Think about it this way. NH2 attacks OH and this causes H20 to be removed. Peptide covalent bond formation is a dehydration/condensation rxn so you would expect H20 to to be removed meaning that of course the OH will have to be the vulnerable one that is attacked. The carbonyl is essentially attacked.
Mole
the amount of a substance that contains the same number of particles that are found in 12g sample of carbon 12
Which property of a substance is best used to estimate its relative vapor pressure? A. Melting point B. Boiling point C. Molecular weight D. Dipole moment
the boiling point of a substance will give the best estimate of its relative vapor pressure. BP is always inversely prop to vapor pressure
Gibbs free energy
the thermodynamic criterion for determining the spontaneity of a reaction G = -nF*Ecell G = -RT ln (Keq) Keq is products/reactants
An electrolytic cell is designed to produce pure copper from CuSO4. An increase in which of the following cell conditions will most effectively increase the rate at which pure copper is produced?
the current of electricity electrolytic cells have a G = +, E = - An electrolytic cell drives a non-spontaneous reaction using electrical energy. In the electrolytic cell, electrons are driven in through the cathode and drawn out through the anode. The rate at which this occurs is the current. By increasing the current, electrons are forced in faster, increasing the rate of reduction, and are withdrawn faster thus increasing the rate oxidation.
Specific rotation
the degree to which chiral molecules rotate plane-polarized light, is unique to each chiral molecule. The value of specific rotation consists of direction (+ or -) and magnitude ( number of degrees). Clockwise = + Counterclock = -
Based on the information in the passage and in Figure 1, what effect does epigenetic modification have on iM pH-dependent denaturation? A. Both methylation and hydroxymethylation result in significantly decreased stability because cytosine is more readily deprotonated. B. Both methylation and hydroxymethylation result in significantly decreased stability because cytosine is more readily protonated. C. Only hydroxymethylation results in significantly decreased stability because cytosine is more readily deprotonated. D. Only hydroxymethylation results in significantly decreased stability because cytosine is more readily protonated.
the drop in pK of the transition denotes a decrease in stability. Because DNA unfolding occurs as the pH increases, it can be inferred that this is due to cytosine deprotonation. Since 5hmC-WT has the lowest pK, hydroxymethylation decreases the stability by increasing the acidity of cytosine
When forming ionic bonds with nonmetals, the reactivity of the alkaline earth metals is observed to increase moving down the column. Based on atomic properties, this trend in reactivity is best explained by comparing:
the energy required to remove an electron from each metal atom
Second ionization energy
the energy to remove two electrons ex: Calcium has a low 2nd IE because it would LOVE to remove 2 electrons so that it becomes stable noble gas
standard heat of formation
the enthalpy change that would occur if one mole of a compound was formed directly from its elements in their standard states
Polarizability
the extent to which an electron cloud of an atom can be distorted by an external charge or by an applied electric field to produce a dipole
Efforts to treat lactic acid buildup in muscles were attempted using dissected muscle specimens in the laboratory. One of these experiments involved ammonium formation from dissolved ammonia. Under conditions of excessive lactic acid:
the final concentration of ammonium will be higher due to the lower pH of the environment. lactic acid donates H+ at low pH to ammonia to make ammonium
standard heat of of reaction
the hypothetical enthalpy change that would occur if the reaction were carried out under standard conditions Hrxn = products - reactants
What would be the elution order for a silica that is polar and an eluent that is benzene? n-Pentane 2-butanone n- butanol propanoic acid
the most nonpolar will elute first. Note that an alcohol is more polar than a carbonyl however not more polar than a carb acid 1) n-Pentane 2) 2-butanone ( ketone) 3) n- butanol 4) propanoic acid
Collision theory
the occurrence of a reaction only when there is a proper orientation between molecules and sufficient energy in all collisions. Reactions will occur only under proper conditions such as when there is enough activation energy and when molecules are oriented correctly.
hydrogen bond ( intermol. force)
the partial positive charge of the hydrogen atom interacts with the partial negative charge located on the electronegative atoms ( F,O, N) of nearby molecules
What are the products of SN2 reaction?
the products always have opposite stereochemistry(R to S, or S to R) from the reactants
A substrate undergoes nucleophilic substitution at a chiral center. What observation would confirm that the reaction proceeded via an SN1 mechanism?
the products lack optical activity The products of SN1 reaction are a 50/50 micture of R and S enantiomers. Enantiomers are stereoisomers which have opposite chiral centers, meaning they will rotate circularly polarized light in exactly opposite directions. If the R and S enantiomers are present in equal amounts, the oppositely polarized rotated light will exactly cancel out and no light will be observed
What will happen to a reaction in equilibrium in response to an increase in pressure?
the reaction will shift towards the side with less gaseous molecules
Limiting reagent If we have a 2:1 ratio of iodine to zinc then which is the limiting reagent?
the reagent that runs out first Iodine is the limiting reagent bc we need more of it for 1 zinc
In locations with very low dissolved O2 concentrations in drinking water, the observed Ksp of ferrous (II) hydroxide will be:
the same equilibrium constants and Ksp are not affected by conx; instead, only affected by temp
Bond enthalpy
the standard heat of reaction can be calculated using the values of bond dissociation energies throughout a system Hrxn = bonds broken - bonds formed
Average molecular speed
the temp of the system dictates the speed of a gas molecule, since it is a measure of the average kinetic energy K = 1/2mv^2 = 3/2 Kb*T Vrms = sqrt [ (3KT)/(m) ] = sqrt [ ( 3KT)/(M) ]
Reduction potential
the tendency of a species to acquire electrons and be reduced. Standard reduction potential E is measured under standard condtions of 25 degrees C, 1M, 1 atm, Reduction potentials (E°) are measured in volts and are defined relative to the standard hydrogen electrode (2 H+ (aq) + 2 e- → H2(g)), which is set at 0 V. Greater (more positive) reduction potentials indicate that a substance 'wants' to be reduced more, while smaller (more negative) reduction potentials indicate that a substance is not prone to reduction.
electron affinity
the tendency of an atom to accept an additional electron by measuring the energy change when an electron is added to an atom
What is Zeff? Zeff increases going _____ and ____ on periodic table
up and right Zeff * due to the presence of protons, the nucleus of an atom is always positive * the attractive force of this positively charged nucleus on the atom's negatively charged valence electrons is termed the effective nuclear charge (Zeff). * zeff increases up and to the right. The reason why we decrease in Zeff as we go down the periodic table is because we are added more shells which means that we are increasing the separation aka adding more shells that act as a barrier between protons in nucleus and valence electrons in the outermost shell so this decreases Zeff
How can we protect carbonyls?
use dialcohols which when replacing the carbonyl will act as an unreactive acetal. After other reactions occur, the protecting groups can be removed with aqeous acid (H20 and catalyzed H+)
What is the mass of water necessary to generate 11.2L of hydrogen gas if calcium metal reacts with water at standard temp and pressure (STP)?
use the balanced equation (11.2L H2 gas) * [1 mol gas/22.4L gas]* [ 2mol H20 / 1 mol H2] * [18.0g water/1mol water] = 18g water
Standard reduction potentials AKA total standard potential generated by a cell, Ecell
used to calculate the standard electromotive force (emf or Ecell) of a reaction aka the difference in potential between two half cells emf = E red, cathode - E red, anode
Indicator function
used to visually detect the endpoint of an acid-base titration. A good indicator must not react with the substance being titrated and should change color close to the equivalence point of titration
Chromatagraphy What is the Rf equation?
uses a stationary phase and a mobile phase to separate compounds based on polarity and/or size Rf: solute distance traveled/solvent distance
Insulators
valence electrons are tightly bound to their atoms, and it takes a great deal of energy to free them from their atomic energy levels
Hydrolysis of an ester means adding ______ to the ester
water 1) ester first gets protonated on the carbonyl O to make it positive 2) water acts like an acid to attack carbonyl, pushing off the carbonyl and getting rid of the positive 3) water loses an H to central O of ester so now its just OH 4) carbonyl reforms and pushes off the ester attachment 5) now we have carb acid and a primary alcohol
Hydrolysis of an amide means that we are adding _______ to an amide
water 1) amide first gets protonated on the carbonyl O to make it positive 2) water acts like an acid to attack carbonyl, pushing off the carbonyl and getting rid of the positive 3) water loses an H so now its just OH ( we do this so that when we reform the carbonyl, we dont push off the water 4) carbonyl reforms and pushes of NH3 5) now we have carb acid and ammonia
What is the frequency of the emitted gamma photons in the decay of I 131?
we want frequency which is in hertz and the equation is v = wavelength*f f = v/ wavelength WE DON'T HAVE WAVELENGTH SO USE SOMETHING ELSE E = hf or E = hc/wave Clearly we can only use E = hf f = E/h = 364keV/ 6.6*10^-34 HOWEVER you need to remember that an electron volt is: V = J/C First convert keV units to eV since eV is same as J/C 364keV = 364000eV = 364000 J/C [ (364000J/C ) (1.6*10^-19 C) ] / 6.6*10^-34 = 8.7 * 10^19 Hz * note that we got 1.6*10^-19 C from it being the electric charge for a single electron which must be acknowledged in solving
in gen chem and ochem what do we refer to stabilization in charge as?
we want to balance a + with a - charge
a buffer solution is made of
weak acid and its conjugate base
Indicator is typically a ____
weak acid or weak base
What strength of reducing agent do you use to reduce a ketone to 1 alcohol?
weak or strong works weak: NaBH4 strong: LiAlH4
What strength of reducing agent do you use to reduce an aldehyde to 1 alcohol?
weak or strong works weak: NaBH4 strong: LiAlH4
dispersion foces /London ( intermol. force)
weakest of all three interbonds all molecules experience these stem from instantaneous dipoles, which are transient dipoles created by the random movement of electron within a molecule. The bonding electrons in covalent bonds may appear to be equally shared between two atoms, but at any particular point in time they will be located randomly throughout the orbital . This permits unequal sharing of electrons, causing transient polarization and counterpolarization of the electron clouds of neighboring molecules, inducing the formation of more dipoles ex: London disp forces increase with size of comp
Vacuum distillation is used when
when a liquid has a boiling point above 150C. The pressure is lowered thereby lowering BP. Boiling occurs when the vapor pressure of the subatnce equals the atmospheric pressure. We boil something by increasing the temp and vapor pressure. We can also lower BP by reducing Patm ( via vaccum distillation)
What are the x and y axis of a Pourbaix diagram? What are the horizontal lines in a Pourbaix diagram?
x-axis: pH y-axis: Potential (voltage) horizontal lines indicate equilibrium which means that that the two molecules on either side are independent of the solution pH (aka the equilibrium is unaffected by changing the pH)
Are amides and carboxylic acid with short hydrocarbon chains water soluble? long chains?
yes bc they form hydrogen bonds in an aqueous solution long chains are not soluble bc they are more hydrophobic