chem
burning splint test did not make the sound of a "pop"
(indicating the ignition of hydrogen gas), the evidence does not support that H2 was present in the reaction flask.
specific heat c
(the amount of heat required to increase 1 g of a substance by 1°C),
When the conditions are such that a reaction is irreversible (eg, low temperature),
, it is said to be under kinetic control, and the most favorable product is the one whose pathway has the lowest activation energy.
Which of the following statements describe a characteristic of an ideal gas?
1. There are no attractive or repulsive forces between the gas molecules. 2. The size (molecular volume) of the individual gas molecules is negligible. 3. Collisions between the gas molecules are completely elastic. 4. Ideal gas molecules have an average kinetic energy (energy of motion) that is directly proportional to the gas temperature.
Na2CO3 + HCl → CO2 + H2O + NaCl Consider the above unbalanced equation. For this reaction, how many mL of a 2 M solution of Na2CO3 are required to produce 11.2 L of CO2 at STP?
250 mL
A fuel cell is a type of galvanic cell whose reactants are continuously supplied at the anode and cathode, and whose products are continuously removed from the system.
Although outside material is continuously supplied to the fuel cell, its reaction is still spontaneous, meaning that the Eocell is positive.
electrolytic cell
An electrolytic cell drives a non-spontaneous reaction using electrical energy. 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 By increasing the current, electrons are forced in faster, increasing the rate of reduction, and are withdrawn faster thus increasing the rate of oxidation.
open system
An open system allows heat and matter to be exchanged with the surroundings.
Unassisted expiration is possible under the effects of anesthesia due to:
B.the elasticity of pulmonary tissue.
light energy
Because light energy is inversely proportional to the wavelength, the line emission at 410 nm (the shortest wavelength in the line spectrum) must correspond to the electron originating in the highest-energy orbit
change in temperature leads to a change in Keq
Because the reaction is exothermic, raising the temperature causes the reaction to be driven toward the reactants, increasing their concentration and causing a decrease in Keq
Which of the following will decrease the percentage ionization of 1.0 M acetic acid, CH3CO2H(aq)?
C. Adding concentrated HCl(aq) HCl is a strong acid that will increase the amount of H+ in solution and thus dec rease the percentage of CH3CO2H that ionizes.
dilution factor
Concentration ratio = [stock solution] / [standard solution]
Which of the following alkali metals is LEAST likely to accept an additional electron?
D.Cs
Density
Density is mass/volume
Nernst equation
Ecell= E°cell - (RT/nF) (lnQ)
standard potential
E∘cell=E∘cathode−E∘anode
alkaline-earth metals
Group 2 of the periodic table contains the alkaline-earth metals, which are a highly reactive family of metals with only two valence electrons that are readily lost to form cations with an oxidation state of +2. Alkaline-earth metals react with water to form hydrogen gas and either a basic hydroxide or an oxide, and the reactivity increases with increasing atomic number. Both alkali metals and alkaline-earth metals show an increase, not a decrease, in reactivity with increasing atomic number.
"as a dipolar ion in aqueous solution"
High dipole moment In addition, molecules that contain strongly electron-withdrawing or electron-donating substituents are highly polar and possess correspondingly high dipole moments.
In the standard state, Keq is related to spontaneity:
If ln(Keq) is positive, ΔG° is negative and the reaction is spontaneous. The natural logarithm (ln) of any number greater than 1 is positive, so Keq must be greater than 1 for the reaction to be spontaneous under standard state conditions. If ln(Keq) is equal to 0, the entire right side of the equation is equal to 0 and the system is at equilibrium in the standard state. This occurs when Keq = 1 because ln(1) = 0 (Choice C). If ln(Keq) is negative, then a negative number (−RT) is multiplied by another negative number (ln[Keq]), making ΔG° positive and the reaction nonspontaneous. The natural logarithm of any number between 0 and 1 is a negative number (Choice B).
magnetic properties
If unpaired electrons remain, then the atom is paramagnetic and the unpaired electrons will interact with a magnetic field. If all electrons are paired, then the electrons will not interact with a magnetic field and the atom is diamagnetic.
beta decay
In all three forms of beta decay, the mass number remains unchanged whereas the atomic number either increases (β− decay) or decreases (β+ decay and electron capture) by 1.. As the atomic number changes, the identity of the element changes accordingly.
A disproportionation reaction is a redox reaction in which both the oxidation and the reduction occur to atoms of the same element.
In both the second and third reactions, manganese participates in both oxidation and reduction (i.e., disproportionation occurs).
educing agent gives up electrons and causes a reduction to occur in another compound.
In the process, the reducing agent itself undergoes oxidation due to losing the electrons.
KaKb = Kw or pKa + pKb = pKw
Kb = (1.0 × 10−14 M2)/(1.0 × 10−9 M) pKb = −log(Kb) pKb = −log(1.0 × 10−5) pKb = 5 pKb = 14 − 9 = 5
Why did the liposomes fluoresce during size-exclusion chromatography?
Liposomes can be difficult to detect since they do not absorb visible light and many molecules absorb UV light. The experimental design allowed fluorescent dye to be trapped inside during liposome formation, which allowed their detection by fluorescence spectroscopy.
1 atm=760 mmHg=760 torr=101,325 Pa=101.325 kPa
P=F/A
Spherical mirrors
R=2f radius of curvature R of a spherical mirror is twice the focal length f:
resistance (R)
R∝L
The Arrhenius equation relates the rate constant k of a reaction with its activation energy and temperature.
The Arrhenius equation describes the relationship between the rate constant and the temperature and activation energy of a reaction. Both the rate constant and the rate of reaction decay exponentially with increasing activation energy and increase exponentially with increasing temperature. Because catalysts lower the activation energy of a reaction, the rate constant is greater for a catalyzed reaction than for an uncatalyzed reaction.
Ecell=
The cell potential Ecell° can be found by subtracting the standard reduction potential Ered° for the substance being oxidized from that of the substance being reduced
tautomerism.
The equation shows the migration of a hydrogen atom from an α-carbon atom to an oxygen atom. The hybridization of the α-carbon atom and oxygen atom change during the process. This is a description of tautomerism
kinetic friction Fk=μkN
The mass of an object determines its weight, which determines the normal force of an object sliding on a surface. Because kinetic friction is proportional to the normal force (Fk = μkN), kinetic friction depends on an object's mass. The coefficient of kinetic friction μk is independent of the size of the contact surface and the speed between the surfaces.
electromotive force Eocell
The more negative the value of Eo for any given compound, the less likely it is to be reduced.
anionic peptides bind to anion-exchange columns
The net charge of peptide C is -1, whereas the net charge of peptide D is -5. Peptide C would elute at a lower salt concentration than Peptide D.
solubility
The solubility of any substance whose anion is basic will be increased in solutions of low pH, as the basic anion reacts with the H+
surface tension of a liquid refers to the imbalance of intermolecular forces at its surface that makes its surface act as a thin, elastic film. Surface tension arises from cohesive forces (between like molecules) in a fluid
The surface tension of a liquid is a result of strong cohesive forces between its molecules. Surface tension creates a tendency to decrease exposed surface area due to a net inward force at the surface molecules.
galvanic cell is an electrochemical cell that converts chemical energy into electrical energy via an oxidation-reduction reaction.
This reaction occurs spontaneously, and Eocell is a positive value.
Entropy
When ΔS° for a reaction is positive, it indicates that that the system is becoming more random (less ordered) whereas a negative ΔS° corresponds to higher order.
Each proton in the nucleus of an atom contributes one unit of positive charge that exerts an electrostatic attraction on the negatively charged electrons around the atom.
Zeff=Z−S Zeff increases as the atomic number increases.
Co(II) is a dication and is formed from the atomic element by the loss of two 4s electrons. As a consequence, only seven 3d electrons remain in the valence shell.
[Ar] 3d^7
chelate formation reactions,
a metal cation and a ligand react to form one or more rings via a pincer-like coordinate bonding arrangement.
β−-decay
a neutron converts into a nuclear proton and emits an electron.
electron capture
a proton captures an electron near the nucleus and converts into a neutron without a positron or electron emission.
β+-decay (positron emission)
a proton converts into a neutron (the opposite of β−-decay) and emits a positron (an electron with a positive charge).
concentration cell
a type of galvanic cell in which ions diffuse across a membrane, creating a potential. Because concentration is the driving force behind electron transfer, the standard potential of a concentration cell is positive whereas the concentration is different between the two compartments of the cell until it reaches equilibrium.
Keq = 0
absolutely no product is formed. If a chemical reaction takes place, Keq must be a nonzero value.
Which alcohol will most likely undergo substitution by an SN1 mechanism in acidic conditions?
alcohol produces the most stable carbocation (tertiary) and consequently will most easily lose a water molecule upon protonation of the hydroxyl group in acidic media.
closed system
allows heat but not matter to be exchanged with the surroundings.
When a battery is charging, it functions as an electrolytic cell because
an external potential forces the oxidation-reduction reaction to proceed in a nonspontaneous direction. This makes the electromotive force for the cell a negative value
Gas exchange
between the alveolar sacs and the pulmonary capillaries occurs due to passive diffusion and is driven by partial pressure differentials (difference) across the membrane from higher to lower partial pressures.
enthalpies of formation
but ammonia and bleach are consumed, not formed. Therefore, they contribute +350 kJ/mol and +45 kJ/mol of enthalpy, SO SWITCH SIGN standard enthalpies of formation for each component must be multiplied by their stoichiometric coefficients. I
ΔG° and Keq
cannot be equal at temperatures that permit the reaction to occur.
products of the reaction,
cannot be the limiting reactant.
convex
create virtual images.
Increase denominator
decrease value
positive pressure ventilator
directly pumps air into the lungs. This increases alveolar pressure, which causes the lungs to inflate
Turbulent flow
disorganized type of fluid flow that occurs at high velocities, not high pressures. Turbulent flow increases flow resistance, which would impede exhalation.
isolated system
does not allow heat or matter to be exchanged.
Assume the hydrolysis of ATP proceeds with ΔG′° = -30 kJ/mol. ATP + H2O → ADP + Pi Which expression gives the ratio of ADP to ATP at equilibrium, if the [Pi] = 1.0 M? (Note: Use RT = 2.5 kJ/mol.)
e^12 DeltaG/RT
The heat released or consumed in a chemical process is called
enthalpy, and the change in enthalpy is expressed by the term ΔH°.
faraday
equal to one mole of electric charge Because each aluminum ion gains 3 electrons, 0.1 faraday of charge will reduce 0.1/3 moles of aluminum, or 0.033 moles of aluminum
Keq < 1
equilibrium would be shifted toward the reactants and indicate a reaction with a positive ΔG.
thin-lens formula yields
f = (12 cm × 4 cm)/(12 cm + 4 cm) = 3 cm.
LD50
gives the concentration of a substance that is necessary to kill 50% of the group being tested. a small LD50 requires less of a compound for a lethal dose than a compound with a higher LD50.
kinetic energy of a photoelectron is equal to
hf - 3.4 eV = 20.5 eV - 3.4 eV = 17.1 eV work function of 3.4 eV
mole ratio
if the amount of a chemical substance is given in something other than moles (eg, grams), then this amount must be converted to moles first to relate the various species proportions. Molarity is defined as moles of solute per liter of solution. Because molarity expresses concentration in terms of moles, the mole ratio of the solute ions can be multiplied by the concentration of the LaCl3 in solution to find the concentration of individual ions in solution.
electrolytic cell this value is negative,
indicating that the oxidation-reduction reaction is not spontaneous. Because Eocell for this battery is a negative value (−2.0 V), the cell is functioning as an electrolytic cell.
An elementary reaction
is a reaction that proceeds in a single step, and in these reactions, the reaction order of each species is equal to its stoichiometric coefficient. For non-elementary reactions, the order must be determined empirically.
Normal inspiration (negative pressure breathing.)
is initiated by contraction of the diaphragm. As the diaphragm contracts, the volume of the pleural cavity increases and intrapleural pressure (IPP) decreases.
heat capacity C
is the product of an object's mass m and its specific heat:
the acid with the smallest pKa (largest Ka)
is the strongest acid and will yield the solution with the lowest pH.
Conduction
is the transfer of heat through direct physical contact
Radiation
is the transfer of heat through electromagnetic radiation, such as infrared light. Radiation heat transfer is significant only for high temperatures.
Convection
is the transfer of heat through the flow of fluids. Fluids absorb heat from hotter regions and deliver it to colder regions.
law of mass action
is usually expressed with respect to the equilibrium constant of a reaction. However, when applied to the dynamic equilibrium of an elementary reaction, the law of mass action also states that the rate of a reaction is proportional to the molar amount (concentration or partial pressure) of each reactant raised to the power of its reaction order.
reversible (eg, high temperatures)
it is said to be under thermodynamic control. Under these conditions, all products form readily and the most stable product will be favored (ie, the most negative ΔG), as it is least likely to undergo the reverse reaction.
Compounds with larger Ksp
more soluble than compounds with smaller Ksp values. If the Ksp is small, then small changes to [A2+] or [X−] have a much larger impact than would be the case if the Ksp were large.
The total number of molecules that were hydrolyzed can be calculated by
multiplying the rate in µM•s-1 by the time (in seconds) and the volume of the solution (in L) 2.0 × 10-6 mol•L-1•s-1 × 60 s × 1.0 × 10-3 L = 1.2 × 10-7 mol
Adiabatic processes
occur with no heat exchange between the system and the environment.
pH scale is related to the concentration of the hydronium ion (H3O+)
pH = −log[H3O+]
phosphatide =
phospholipid
Keq=e−ΔG°RT ΔG° is negative, the exponent term will become
positive and make Keq > 1, indicating that the equilibrium favors product formation.
effective nuclear charge Zeff,
pulling the electrons closer to the nucleus. Conversely, gaining electrons to form an anion produces greater electronic repulsion and nuclear shielding (lesser Zeff), which pushes electrons farther from the nucleus.
uncompetitive inhibitor
r results in a lower apparent KM and Vmax of the enzymatically catalyzed reaction.
Brønsted-Lowry acids and bases
react to produce an ionic salt and water are classified as acid-base neutralization reactions.
Concave (converging) mirrors create
real images when the object is placed outside the mirror's focal length, whereas convex (diverging) mirrors always create virtual images.
Venturi effect
refers to the reduction of fluid pressure that occurs when flow velocity increases at constricted sections of a tube.
Pulmonary resiliency (elastic recoil and surface tension effects)
refers to the tendency of the lungs to return to their original shape after being stretched during inhalation. Pulmonary resiliency allows for passive expiration and does not require muscles or ATP energy, and can therefore occur under the paralytic effects of anesthesia.
law of mass action
states that a reaction quotient Q can be expressed as a ratio of the molar concentrations of the products over the reactants, each raised to the power of its respective balanced reaction coefficient:
The amount of product formed in a reaction depends on
the equilibrium constant of the reaction. This constant is not changed by the presence or absence of a catalyst, which affects only the rate of the reaction.
For capacitors connected in parallel
the equivalent circuit capacitance is the sum of the individual capacitances: Cparallel=C1+C2+C3+...
Because the masses of both N2 and O2 are equal (1.5 g each),
the gas with the lower molar mass has more molecules.
For capacitors in series
the inverse of the equivalent capacitance is the sum of the inverses of the individual capacitances: 1/Cseries=1/C1+1/C2+1/C3+... For capacitors in series, the circuit equivalent capacitance is always smaller than the smallest individual capacitance in the circuit.
gas chromatograph (gc) trace
the lowest molecular weight and also the weakest intermolecular forces of attraction. This substance will therefore migrate the fastest and be the first peak
In all three forms of beta decay,
the mass number remains unchanged, while the atomic number increases (β−-decay) or decreases (β+-decay and electron capture) by 1. As the atomic number changes, the identity of the element changes accordingly.
for a reaction in which one of the reactants is also the solvent,
the solvent species is omitted from the Keq expression.
rate-determining step.
the step that must overcome the largest energy barrier to pass through the transition state is the
ΔL=αLΔT
thermal expansion of the length L or volume V of a substance is linearly proportional to its change in temperature ΔT:
If two atoms are isoelectronic
they have the same number of electrons
transition state (‡) (activated complex)
transition states are seen graphically as higher energy maxima (peaks). the peak closest to the reactants is the transition state for the first step of the reaction.
kcat
used to describe the rate-limiting step of catalysis under saturating conditions of substrate.
In insulators
valence electrons are tightly bound to their atoms, and it takes a great amount of energy to free them from their atomic energy levels. Electrons in the material cannot easily move from one atom to another.
reaction rate is proportional to the rate coefficient k
which decreases exponentially as the energy needed to reach the transition state increases
change in Gibbs free energy ΔG
ΔG = ΔH − TΔS
Π = iMRT
Π is the osmotic pressure
