Missed Uworld Chem
D.3 times higher. The volume is directly proportional to the number of moles of gas.
Suppose that a multiplace chamber has three times the volume of a monoplace chamber, and both are pressurized to 1.5 ATA with 100% O2 at 29 °C. Compared to that of the monoplace chamber, the number of moles of oxygen in the multiplace chamber would be: A.lower. B.the same. C.2 times higher. D.3 times higher.
C.0.01 L MATH 0.8 g x (1 nol / 156.9 g) x (1 L/0.5 mol)
What volume of the copper(II) sulfate solution should be used in the reaction to deliver 0.8 g of CuSO4 into the reaction mixture? A.1.6 mL B.2.5 mL C.0.01 L D.0.40 L
B.ZPP requires less energy to excite its electrons from the ground state than does PPIX. Because ZPP can be excited by a longer wavelength than PPIX, ZPP requires less energy to excite its electrons from the ground state.***
According to Figure 2, which of the following is true about ZPP detection in blood samples? A.Both ZPP and PPIX emit photons that are equal in energy. B.ZPP requires less energy to excite its electrons from the ground state than does PPIX. C.ZPP and PPIX are excited by photons of equal energy but absorb photons of different energy. D.ZPP and PPIX absorb the same energy, but their electronic transitions are different
C.Both engines would produce the same amount because the equilibrium constant is the same for both. **Platinum is a catalyst!!!! therefore they have the same equilibrium constant - catalysts cannot alter the position of equilibrium
At a given temperature and injection composition, if researchers allowed each engine to carry out only one complete combustion reaction, which engine would produce more water? A.The spark engine would produce more water because it has a lower power output. B.The platinum engine would produce more water because it has a higher rate of combustion C.Both engines would produce the same amount because the equilibrium constant is the same for both. D.Cannot be determined with the available information.
B.Rb+ Because the size of the alkali metal ions increases moving down the column, the elements adjacent to potassium will form ions that are closer to the size of the K+ ion. so Rb is the closest***
At higher concentrations, alkali metal ions close to the size of a potassium ion can displace potassium ions in biological systems and promote low potassium levels (hypokalemia). Which cation is most likely to displace K+ ions? A.Li+ B.Rb+ C.Cs+ D.Fr
D.C-C bond C-C bond is the only single bond that does not involve a first row atom (hydrogen). Therefore, the C-C bond will be the longest and require the least energy to break. longest bond = weakest Atoms with smaller radii (near the top of the periodic table) tend to form shorter, stronger bonds than atoms with larger radii.
Consider the trends in atomic radii on the periodic table. The bond in citrate that is the longest and weakest with the lowest bond dissociation energy is the: A.C-H bond. B.C=O bond. C.O-H bond. D.C-C bond
D.> 1 READ THE QUESTION. says spontaneous ΔG = -RTLnKeq, therefore Keq is positive
If dichloramine formation is spontaneous under standard conditions, the equilibrium constant must be: A.< 0. B.> 0 and < 1. C.= 1. D.> 1
B.1/2 [Cu2(C2H7O4)4] = RATIO x [Na2SO4] 1:2 **LOOK TO SEE WHAT YOUR COMPARING ALWAYS**
In the reaction, just prior to precipitation, what is the ratio of the concentration of copper(II) acetylsalicylate to the concentration of sodium sulfate? A.1/4 B.1/2 C.2/2 D.2/1
C.NaCl ***Greater solubility (higher value) corresponds to a faster corrosion rate.
Magnesium corrodes quickly in the body because Mg2+ combines with anions other than OH− to form soluble salts. Based on the solubility data given in Table 1, which of the following salts, if present, will cause the magnesium implant to corrode most quickly? A.Ca3(PO4)2 B.Ca(OH)2 C.NaCl D.NaF
A.the energy required to remove an electron from each atom.
Moving down the column, the alkaline-earth metals are observed to give increasingly vigorous reactions when forming ionic bonds with nonmetals (Reactions 1-3). Based on atomic properties, this trend in reactivity is best explained by comparing: A.the energy required to remove an electron from each atom. B.the tendency of each atom to attract electrons within a bond. C.the extent to which the electron cloud of each atom can be distorted by an external charge. D.the energy released when an electron is added to each atom
B.< 1 Strong acids ionize essentially 100% in aqueous solutions, resulting in a large acid dissociation constant (Ka > 1), whereas weak acids ionize only to a small extent, resulting in a small acid dissociation constant (Ka < 1).
The aqueous solubility of the NaC9H7O4 salt used for the reaction is very high (≈ 1200 g/L), whereas its conjugate acid, HC9H7O4 (aspirin), is a weak acid with very low solubility (3 g/L). The ionization constant for aspirin is: A.> 1 B.< 1 C.= 1 D.= 0.
B.KH2PO4 During the titration of an acid with a sufficiently strong base, the titration curve exhibits one buffer region and one equivalence point for each acidic proton in the acidic compound structure. therefore need two acidic protons
The figure below shows the titration curve for an acid titrated with aqueous sodium hydroxide. When titrated in solution, which of the following salts would be most likely to produce a similar titration curve? A.(NH4)3PO4 B.KH2PO4 C.Na2HPO4 D.K3PO4
C.6.0 mmol **look at figure and can see 4mmol of OAc needed 524 mg x (1 mmol acetylated 18F-FDG / 348.31 mg) x (4 mmol OAc/1mmol acetylated 18F-FDG) = 6
The last step in the synthesis of 18F-FDG is a hydrolysis reaction to remove the acetyl (OAc) protecting groups. If 524 mg of acetylated 18F-FDG is hydrolyzed, how many millimoles of the acetyl group are removed in the reaction? (Note: The molar mass of the acetylated 18F-FDG is 349.31 g/mol = 349.31 mg/mmol.) A.0.4 mmol B.1.5 mmol C.6.0 mmol D.7.5 mmol
B. II and III I. is strong covalent interactions IV is london dispersion forces!!
The regions from the protein in Figure 2 that exhibit noncovalent hydrogen bonding and ionic bonding, respectively, are: A.I and II. B.II and III. C.II and IV. D.III and IV.
C.Mg2+ Because magnesium has the highest atomic number (greatest number of protons) in the isoelectronic series, Zeff is greatest in this ion, making it the smallest within the given series.
The regulation of mineral ions in the cellular fluids of biological systems is performed by ion pumps that selectively transport ions of specific size and charge across cellular membranes. Which of the following isoelectronic species is the smallest ion? A.Na+ B.F− C.Mg2+ D.O2−
A.I only solution = more than one molecule so will NOT be intramolecular forces, has to be between two molecules so has to be I (II false) freezing = colligative property = a function of the amount of solute but not the solute's chemical properties. (III false)
Which of the following affects the freezing point of an ideal solution? I. The strength of intermolecular forces II. The strength of intramolecular forces III. The reactivity of the solute A.I only B.II only C.I and III only D.II and III only
B.The net charge of heme is zero. (dotted lines represent resonance and a distribution of charge, so the nitrogens would share the charge with iron) If formal charge is shown pay attention!! coordinate covalent bonds = a covalent bond in which both electrons came from the molecule when it was formed. Thus it is the product of a lewis base/lewis acid reaction - iron is electrophile so needs to have empty d orbital for nitrogens electrons to enter (c is wrong) d - wrong because orbital overlap is best between similar energy orbitals
Which of the following does NOT describe the coordinate covalent bonds formed between Fe2+ and the four nitrogen ligands in Figure 1? A.Each nitrogen atom provides both bonding electrons. B.The net charge of heme is zero. C.Nitrogen's electrons interact with iron's d orbitals. D.Iron's electron configuration determines bond strength.
B.Group 3 transition metals are NOT representative elements
Which of the following element groups is NOT included in the representative elements? A.Group 1 B.Group 3 C.Group 13 D.Group 18
D. CN- + H20 ---> OH- +HCN SO Kb = [OH-][HCN]/[CN-]
Which of the following is the base dissociation constant Kb for the conjugate base of HCN?
B.9,000 **Keep in 0.9 decimal form*** 0.9/100 = x/1,000,000 x = 9,000***
Which of the following values gives the number of parts per million (ppm) of NaCl in a 0.90% saline solution? A.900 B.9,000 C.90,000 D.900,000
C.3s orbital. According to the filling order, the lowest energy configuration (ground state) of a sodium atom is 1s22s22p63s1. As such, an electron configuration of 1s22s22p63p1 for a sodium atom in an excited state indicates that the excited atom has a vacant 3s orbital (absent in the configuration) and an excited electron in the 3p orbital. Therefore, the excited electron occupying the 3porbital was excited from the 3s orbital. (The 3p orbital is unoccupied in the ground state and cannot be the orbital from which the electron is excited.)
A sodium atom in an excited state has an electron configuration of 1s22s22p63p1. The excited electron within the configuration was excited from the: A.2s orbital. B.2p orbital. C.3s orbital. D.3p orbital.
C.Yes, because according to the Aufbau principle, electrons fill lower energy levels first. The Aufbau principle states that low energy orbitals are filled first** pay attention to question** open periodic table**
For the electron configuration of iron, Fe(0), do electrons fill the 4s orbitals before the 3d orbitals are filled? A.Yes, because electrons fill the s and p orbitals before they fill the d orbitals, even if they are in different energy levels. B.No, because 3d orbitals are lower in energy than 4s orbitals. C.Yes, because according to the Aufbau principle, electrons fill lower energy levels first. D.No, because orbitals are filled based on the order of the principal quantum number, and 3d comes before 4s
C. fluorine with the same chemical properties as 18F. The chemical behavior of an atom is determined primarily by its electron configuration, not by the number of neutrons in the nucleus. As a result, isotopes of the same element have nearly identical chemical properties (such as bonding and reactivity) but differ in their physical properties (such as density and mass).
Suppose that the (p-n) nuclear reaction described in the passage was attempted but resulted in the 18O nucleus absorbing a proton without ejecting a neutron. The resulting nucleus formed would be an isotope of: A.fluorine with different chemical properties than 18F. B.oxygen with the same chemical properties as 18O. C.fluorine with the same chemical properties as 18F. D.an element other than O and F with different chemical properties.
D.18.0 g 11.2 L x (1 mol H2/22.4 L) x (2 mol H20/1 mol H2) x (18 g H20/1 mol H20) Ca + 2H20 --> Ca(OH)2 + H2 AT STP VOLUME is 22.4L/mol***
What is the mass of water necessary to generate 11.2 L of hydrogen gas if calcium metal reacts with water at standard temperature and pressure (STP)? A.2.0 g B.4.5 g C.9.0 g D.18.0 g
B.20%
What is the mass percent of alcohol in a solution containing 62 mL of ethyl alcohol mixed into 200 mL of water? (Note: Density of ethyl alcohol = 0.8 g/mL; density of water = 1 g/mL.) A.16% B.20% C.25% D.31%
B.4.9 × 10−4 g/mL find moles of He first!!!
Assume that helium behaves as an ideal gas. What is the estimated density of 1.0 g of helium gas at a temperature of 27 °C and a pressure of 3.0 atm? (Note: Use R = 0.0821 L∙atm∙mol−1∙K−1) A.1.2 × 10−4 g/mL B.4.9 × 10−4 g/mL C.1.4 × 10−3 g/mL D.5.4 × 10−3 g/mL
B.2O + 2O2 → 2O3 Since O2 split, O + O has to be in the reactants only one that does that is B
Ozone (O3) in the atmosphere protects against harmful UV radiation. Its formation proceeds in two steps and is initiated when molecular oxygen (O2) splits into two oxygen atoms upon absorption of UV light. Which of the following would be the second step if ozone formation goes to completion? A.O + O2 → O3 B.2O + 2O2 → 2O3 C.3O2 → 2O3 D.O + 2O2 → O3
D.7/2 moles O2 44.8 L NH3 x (1 mol NH3 / 22.4L NH3) x (7 mol O2/ 4 mol NH3) = 7/2 moles O2
When ammonia burns in air, nitrogen dioxide and water are produced according to the reaction below: 4 NH3(g) + 7 O2(g) → 4 NO2(g) + 6 H2O(l) At 0 °C and 1 atm pressure, burning 44.8 L of ammonia requires: A.6/7 moles O2 B.8/7 moles O2. C.7/4 moles O2. D.7/2 moles O2
D most hydrophobic character = the molecule in which the highest percent of its structure made of nonpolar parts
Which of the following molecular structures has the most hydrophobic character?
D.4 times lower. NaCl -> Na + Cl MgCl2 --> Mg + 2Cl NaCl: 1 L x (0.005 mol/1L) (1 mol NaCl / 1 mol Cl) = 0.005 MgCl2: 1 L x (0.01 mol / 1 L) x (2 mol Cl / 1 mol MgCl) = 0.02 5 x 10^-3 / 20 x 10^-3 = 1/4
Suppose that Experiment 2 is repeated using chloride salts of the Group 1 metals. Compared with the concentration of Cl− in the 10 mM Mg2+ solution, the concentration of Cl− in the 5 mM Na+ solution would be: A.higher B.the same C.2 times lower. D.4 times lower.
D.4.8 atm Πgastric / Πlab acid = Mgastric/Mlab =Πgastric / 1.9 = 0.1/0.04 Πgastric / 1.9 = 2.5 Πgastric = 1.9 x 2.5 = 4.8
A 0.040 M HCl solution is measured in the laboratory and has an osmotic pressure of 1.9 atm. What is the estimated osmotic pressure of gastric acid (approximated as 0.10 M HCl) under the same conditions? A.0.19 atm B.0.40 atm C.2.4 atm D.4.8 atm
D.The cylinder solution density will increase, and the glass bulb will float. density of a solution will increase as it cools, which will make the glass bulb less dense relative to it and can float Solid objects float in liquids with a higher comparative density and sink in liquids with a lower comparative density
A Galileo thermometer consists of a cylinder filled with a known solution and several sealed glass bulbs partially filled with water. Each bulb effectively acts as an isolated system. If one of the bulbs has the same density as the solution at 25 °C, how will its position and the density of the solution change as the temperature of the solution decreases from 25 °C to 20 °C? A.The cylinder solution density will decrease, and the glass bulb will sink. B.The cylinder solution density will decrease, and the glass bulb will float. C.The cylinder solution density will increase, and the glass bulb will sink. D.The cylinder solution density will increase, and the glass bulb will float.
D **emission must be an electron relaxing to a lower n-level (absorption (a) would be getting excited from a lower level to a higher n-level
According to the Bohr model of the atom, which of the diagrams below represents the spectral line at 410 nm in the emission line spectrum?
A.Li **Alkali metals occupy Group 1 and have the lowest first ionization energies of all the element groups. The first ionization energy tends to increase with increasing atomic number moving across a period and decrease moving down a group on the periodic table.
According to trends in the first ionization energy, which of the following alkali metals is the LEAST reactive? A.Li B.Na C.K D.Cs
D.C4H4N2O An empirical formula may be calculated from the known mass of each type of atom in a compound sample by calculating the number of moles of each. Dividing each mass given in the question by the atomic mass of the atom yields the number of moles. For these calculations, grams and moles are scaled down to milligrams and millimoles: Carbon: 36 mg12 mg/mmol=3 mmol Hydrogen: 3 mg1 mg/mmol=3 mmol Nitrogen: 21 mg14 mg/mmol=1.5 mmol Oxygen: 24 mg16 mg/mmol=1.5 mmol Dividing each molar amount by the smallest molar amount (1.5 mmol) yields the relative ratios of each type of atom: C:H:N:O = 2:2:1:1. Therefore, the empirical formula of the compound is C2H2NO, which has a molecular weight of 56 g/mol so we need to double to find molecular which is
An 84-mg sample of a compound is found to contain 36 mg of carbon, 3 mg of hydrogen, 21 mg of nitrogen, and 24 mg of oxygen. If the compound has a molecular weight of 112 g/mol, what is its molecular formula? A.C2H2NO B.C4H6N3O C.C5H6NO2 D.C4H4N2O
B.5.0 × 10−13 Ksp=[M2+][OH−]^2 The equilibrium shows that 2 moles of OH− are produced for every 1 mole of M2+. As a result, [M2+] is equal to half of [OH−]: [M2+]= 0.5[OH−] = 0.5(10−4) = 5×10^−5 Ksp = (5×10^−5)(10^−4)^2=5×10^−13
An unknown metal M forms an ionic hydroxide with the formula M(OH)2 that exhibits the equilibrium in a saturated aqueous solution. If the solution pH is 10, the solubility product constant Ksp of the compound is: A.5.0 × 10−31 B.5.0 × 10−13 C.1.0 × 10−12 D.1.0 × 10−8.
C.5/R do PV=nRT for both sides (convert 27 °C to Kelvin = 27 +273 = 300 1 (1500l) = n1R(300K) n1 = 5/R 2(1500) = n2R(300K) n2 = 10/R n2-n1 = moles added to the chamber 10/R - 5/R = 5/R
Assume that the pressure in a 1500 L monoplace chamber is increased from 1 ATA to 2 ATA. Which expression gives the number of moles of oxygen that is added to the chamber if the temperature remains constant at 27 °C? A.(4.5 × 105)R B.10/R C.5/R D.0.2R
B.Law of mass action The law of mass action states that the rate of a reaction is proportional to the molar amount of each reaction component raised to the power of its reaction orde (Henry's law states that the amount of a gas that dissolves in a liquid is proportional to the partial pressure of that gas. It is not predictive of the reaction rate.)
Assuming the combustion of hydrogen behaves like an elementary reaction with respect to its rate, which of the following explains why an increase in the H2/O2 ratio causes an increase in the reaction rate? A.Pauli exclusion principle B.Law of mass action C.Boyle's law D.Henry's law
C.1.0 mmol [H+] = 10^-pH, pH = 1 [H+] = 10^-1 = 0.1 M 0.1 mmol/mL x 10 mL = 1 mmol
Based on the biological system described in the passage, how many millimoles of hydrogen ions are present in 10.0 mL of gastric acid? A.100 mmol B.10 mmol C.1.0 mmol D.0.10 mmol
A.I only LD50 = the amount of substance that would kill 50% of the population -low LD50 = potent substance = readily diffuses across membrane
Based on the experimental data in Table 1, which cyanide compound(s) likely diffuse(s) most readily across the gastric lipid membrane? I. HCN II. NaCN III. KCN A.I only B.II only C.I and III only D.I, II, and III
B.−470 kJ/mol REMEMBER MOLES OF EVERYTHING** take into account moles
Based on the information given in the passage, which of the following is the standard molar enthalpy of formation for sodium hydroxide? A.−590 kJ/mol B.−470 kJ/mol C.−940 kJ/mol D.550 kJ/mol
C.II and III only I. NO ***NO3 never forms precipitate also Cu is a common ion so would lead to precipitation of both II. YES sulfate only would precipitate CuSO4 III. YES higher difference in solubilities as indicated by the graph at 5°C IV. NO lower pH would not decrease either side since none of the ions are acidic
Based on the passage, which of the following procedures would assist in separating an aqueous mixture of CuCl2 and CuSO4 salts at 90 °C? I. Add Cu(NO3)2 to the solution mixture II. Add Na2SO4 to the solution mixture III. Cool the solution mixture to 5°C IV. Lower the pH of the mixture A.I and II only B.I, II, and III only C.II and III only D.II, III, and IV only
B.endothermic, because the slope of the trend line is negative, and therefore ΔH° is positive. −m=−ΔH°R mR=+ΔH° slope is negative, so ΔH must be positive which indicates endothermic
Based on the van 't Hoff plot shown in Figure 1, the dissociation of acetic acid is: A.endothermic, because the y-intercept of the trend line is positive, and therefore ΔS° is positive. B.endothermic, because the slope of the trend line is negative, and therefore ΔH° is positive. C.exothermic, because the slope of the trend line is positive, and therefore ΔH° is negative. D.exothermic, because the y-intercept of the trend line is negative, and therefore ΔS° is negative.
A. Ca Electrical conductivity = METALS
Considering the type of element represented by each of the following, which of the elements below is most likely to have the highest electrical conductivity? A.Ca B.Si C.Se D.I
D.The equilibrium between Cu2+ and CuO is independent of applied potential above +0.3 V at a pH of 7
Copper plays a vital role as a trace mineral for biological processes, including the electron transport chain and collagen synthesis. The Pourbaix diagram below outlines the relationship between several copper species as a function of solution pH and applied potential. Which statement accurately describes the chemical changes shown in this diagram? A.The predominant species at a potential of −0.2 V and pH of 13, is CuO. B.Cu2+ is reduced and precipitates as Cu2O as pH increases to a pH of 8 at a potential of +0.3 V. C.Cu is reduced to Cu2+ as the potential is changed from −0.4 to +0.2 at a pH of 4 D.The equilibrium between Cu2+ and CuO is independent of applied potential above +0.3 V at a pH of 7
B.increases, and the energy of the reactants is less than the energy of the products. **established reaction is endothermic** In an endothermic reaction, energy (in the form of heat) is absorbed by the system from the surroundings as the reaction proceeds. As a result, an endothermic reaction has a positive ΔH° (ΔH° > 0), which indicates that the products have higher energy than the reactants
During the dissociation of acetic acid at the temperatures tested in Table 1, the molecular disorder within the reaction vessel: A.increases, and the energy of the reactants is greater than the energy of the products. B.increases, and the energy of the reactants is less than the energy of the products. C.decreases, and the energy of the reactants is greater than the energy of the products. D.decreases, and the energy of the reactants is less than the energy of the products.
B.Adding F− as the common ion would cause CuF2 to precipitate. Although adding F− as the common ion would cause CuF2 to precipitate, it would also cause BaF2 to precipitate. The fact that adding F− precipitates CuF2 does not indicate why precipitating CuF2 is a better choice than precipitating BaF2 (Choice B).***** Because the Ksp of CuF2 (1.6 × 10−6) is smaller than the Ksp of BaF2 (3.0 × 10−6), a saturated aqueous mixture of CuF2 and BaF2 will have fewer moles of CuF2 present in the solution and less CuF2 to remove from the solution during a separation (Choice C) 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. Therefore, CuF2 (smaller Ksp) is more responsive than BaF2 (larger Ksp) to small changes in common ion concentrations (Choice A), and fully precipitating BaF2 would require a greater number of common ions to be added to the solution (Choice D).
For the separation of a saturated aqueous mixture of CuF2 (Ksp = 1.6 × 10−6) and BaF2 (Ksp = 3.0 × 10−6), a lab technician chose to use the common ion effect to precipitate CuF2 from the solution rather than BaF2. Which of the following statements does NOT explain why precipitating CuF2 is the better choice for the separation procedure? A.CuF2 is less soluble and more responsive to small changes in common ion concentrations. B.Adding F− as the common ion would cause CuF2 to precipitate. C.There are fewer moles of CuF2 to remove from the solution than moles of BaF2. D.Precipitating BaF2 would require a greater number of common ions to be added to the solution
B.5.4 × 10^20 ***pay attention to not only the concentration they give (0.1) but also the amount (9mL)***** 9mL x (1L/1000mL) x (0.1moles/1L) x (1mol La3+/1 mol LaCl3) = 9 x 10^-4 9 x 10^-4 x (6.02 x 10^23/1 mol) = 54 x 10^19
How many La3+ ions are present in each of the unknown samples? A.1.5 × 10^−27 B.5.4 × 10^20 C.9.0 × 10^20 D.6.0 × 10^22
B.2 If H2PO4− is fully neutralized, two acidic protons must be neutralized and an equivalence point would be seen in the titration curve for each of the protons. This indicates that a total of two equivalents of NaOH would be required to fully neutralize the H2PO4− (one OH− from NaOH for each H+).
If f the titration of H2PO4− in a urine sample was continued until all of the acid in the solution was neutralized, how many equivalents of NaOH would be needed to fully neutralize the solution? A.1 B.2 C.3 D.4
B.Ksp and equilibrium pH will both increase. HEAT will drive reaction more to the right** so OH- will increase (H decrease), therefore increase in pH. Ksp can also be changed with temp** If increase temp, more salt dissolved to Ksp increases!!
If researchers wanted to replicate physiological conditions by increasing the SBF temperature to 37°C, how would this change affect the solubility product constant and equilibrium pH of Mg(OH)2 dissolution? A.Ksp will decrease and equilibrium pH will increase. B.Ksp and equilibrium pH will both increase. C.Ksp will stay the same and equilibrium pH will increase. D.Ksp will stay the same and equilibrium pH will decrease.
C density = mass/volume volume of a cube = cm^3 = (2r)^3
If the atomic radius r is 1.67 × 10−8 cm and the mass of one polonium atom is 3.47 × 10−22 g, which expression correctly calculates the density of a pure sample of solid polonium?
C.5.9 mol/L **you're not comparing so you dont need to do mole ratio** (120 g NaC9H7O4/100 mL) x (1000 mL/1L) x (1 mol/ 202.2g NaC9H7O4) = 5.9
If the solubility of sodium acetylsalicylate is roughly 120 g per 100 mL of water, what is the approximate molar concentration of the saturated NaC9H7O4 solution used in the reaction? A.0.006 mol/L B.0.59 mol/L C.5.9 mol/L D.1,200 mol/L
B.5.91 M ****this is what Ksp is referring to***
If the solubility product constant Ksp for NaC9H7O4 is estimated to be 34.9, what is the approximate acetylsalicylate ion concentration in the saturated NaC9H7O4 solution used for the reaction? A.2.95 M B.5.91 M C.17.4 M D.34.9 M
D.O2, because oxygen gains electrons. **oxidizing agent gains electrons Oxygen (O2) is among the simplest and most readily available of the common oxidizing agents
In Reaction 1 shown in the passage, the oxidizing agent is: A.K2MnO4, because potassium loses electrons. B.MnO2, because manganese gains electrons. C.KOH, because hydrogen loses electrons. D.O2, because oxygen gains electrons.
C.Citrate reduces the hydronium concentration in urine. Citrate is a weak base and therefore a proton acceptor. It can alkalinize a solution by removing protons from hydronium ions, converting those ions to water and reducing the total hydronium concentration. Therefore, citrate may increase the solubility of uric acid by reducing the hydronium concentration and may decrease the risk of uric acid kidney stones.
In addition to calcium oxalate stones, researchers might hypothesize that potassium citrate (a weak base) could reduce the risk of uric acid stones for which of the following reasons? A.Potassium reduces the hydroxide concentration in urine. B.Potassium increases the hydroxide concentration in urine. C.Citrate reduces the hydronium concentration in urine. D.Citrate increases the hydronium concentration in urine.
B. .4.0 × 10−5 M **STEP ONE: ICE CHART Ksp = [Cu][F-]^2 CuF2(s) ⇄Cu2+(aq)+2 F−(aq)) I 0 0.2 M C +x +2x E x 0.2 + 2x **CAN TREAT 0.2 + 2x = 0.2 Ksp = [Cu][F-]^2 1.6 × 10^−6 = [x][0.2^2] 1.6 × 10^−6 = [x][0.4] x = 4.0 × 10−5 M
In pure water at 25 °C, the concentration of a saturated solution of CuF2 is 7.4 × 10−3 M. If measured at the same temperature, what is the concentration of a saturated solution of CuF2 in aqueous 0.20 M NaF? ( Ksp = 1.6 × 10^−6 & CuF2(s) ⇄ Cu2+(aq)+2 F−(aq)) A.8.1 × 10−6 M B.4.0 × 10−5 M C.7.4 × 10−3 M D.6.4 × 10−2 M
C.It increases the average kinetic energy of nearby molecules. Temperature is a measure of the average kinetic energy of the molecules in a system. At higher temperatures, the molecules move more quickly and collide more often and with more energy. Therefore, an increase in temperature will increase the rate of a reaction by providing more molecules with the required activation energy. spark = increase in temperature (the equilibrium position of a reaction is not appreciably altered by the presence of a spark. Instead, the rate at which equilibrium is achieved changes.**)
In the absence of platinum, a spark initiates combustion by doing which of the following? A.It shifts the reaction equilibrium toward water formation. B.It consumes oxygen, driving the reaction toward the products. C.It increases the average kinetic energy of nearby molecules. D.It removes electrons from oxygen to form reactive oxygen species
D.N and O only During the formation of copper(II) glycinate (Figure 1), glycine displaces acetate in Cu(C2H3O2)2 because stronger Lewis bases can displace weaker Lewis bases as ligands within a complex. Stronger Lewis bases tend to be those that have lone pair electrons on atoms with a net charge and/or a lower electronegativity. N and O are lewis bases because donate electrons (PUSH ARROWS) also Cu2+ is electron deficient so how could donate electrons? cant!! so you know is lewis acid not the base
In the reaction to form the cis isomer shown in Figure 1, which of the following structural sites function(s) as a Lewis base? A.Cu only B.N only C.O only D.N and O only
have no effect on the pH of the solution. An indicator is used in acid-base titrations to determine the endpoint of a titration. A good indicator should change color close to the equivalence point of a titration.
Indicators
B.0.28 Osmol/L ***PUT TEMPERATURE IN KELVIN osmolarity = Π/RT = 6.9 / 0.08 x (31 + 273) **Whenever using a constant, all the other units must MATCH THE CONSTANT
Osmolarity, the number of moles of osmotically active species (osmoles) per liter of solution (Osmol/L), equals the molar solute concentration M multiplied by the van 't Hoff factor i. Osmolarity is calculated by dividing osmotic pressure Π by RT, where R is the gas constant and T is the absolute temperature. If the osmotic pressure of blood plasma is 6.9 atm at 37 °C, what is its osmolarity? (Note: Assume R = 0.08 L·atm/mol·K, and i = 2.) A.0.14 Osmol/L B.0.28 Osmol/L C.1.2 Osmol/L D.2.3 Osmol/L
B.Oxygen's valence electrons experience more electron-electron repulsion than other Group 6A elements. Electron-electron repulsions result in a decreased electron affinity.** since oxygen is smaller, the valence orbitals have less space than larger elements in the column, and thus electron-electron repulsion will be higher
Oxygen is the most electronegative element of Group 6A. However, it also has the lowest electron affinity in the group. What factor can be used to explain this discrepancy? A.Oxygen is less stable than the other Group 6A elements. B.Oxygen's valence electrons experience more electron-electron repulsion than other Group 6A elements. C.Oxygen's valence electrons are more shielded from the positively charged nucleus than other Group 6A elements. D.Oxygen does not have d orbitals available for additional electrons
B. MES The pKa of a buffer is related to its acid dissociation constant (Ka) by the equation pKa = −log(Ka). A buffer with a pKa of 6 has a Ka of 10-6, and a buffer with a pKa of 7 has a Ka of 10-7, so a buffer with a Ka value between 10-6 and 10-7 would have a pKa near 6.3. MES meets this requirement with a Ka of 7.1 x 10-7 and would therefore be the best of the available buffers for mimicking the pH of the medial Golgi.
Researchers wished to mimic the conditions of the medial Golgi (pH ≈ 6.3). Which of the buffers shown in Table 1 would be best suited for this experiment? Acetic acid B.MES C.HEPES D.Tris
C.5.2 M Solution 1: 0.8 L x (3 mol K2MnO4 / 1L) x (2 mol K+/1 mol K2Mn04) = 4.8 mol K+ ion Solution 2: 0.2 L x (2 mol KMnO4/1 L) x (1 mol K+ / 1 mol KMnO4) = 0.4 mol K+ ion TOTAL moles: 0.4 + 4.8 = 5.2 mixture molarity = 5.2 / 1 L = 5.2 M K+ ion
Suppose 0.80 L of 3.0 M aqueous K2MnO4 is combined with 0.20 L of 2.0 M aqueous KMnO4 to make a solution. What is the concentration of potassium ions in the solution? A.2.8 M B.4.0 M C.5.2 M D.6.0 M
A. Perform the reaction under acidic conditions Comparing the slopes of the line segments between ClO4− and ClO3− for both pH 0 and pH 14 on the Frost diagram of chlorine (Figure 1 in the passage), the slope for acidic conditions (pH 0) is greater than the slope for basic conditions (pH 14). Therefore, performing the experiment under acidic conditions will make the reduction of ClO4− more favorable during the reaction.
Suppose an experiment is to be performed utilizing a reaction that reduces ClO4− to ClO3−. Which experimental approach can be expected to make the reduction of ClO4− more favorable during the reaction? A.Perform the reaction under acidic conditions B.Perform the reaction under neutral conditions C.Perform the reaction under basic conditions D.The pH of the reaction mixture does not make a difference
A.Cu(NO3)2 ***when using precipitation to separate two compounds that have a common ion, use the ion that is not shared to accomplish this so that the solid precipitates ***if using common ion, determine which precipitates first calculating the ion concentration that each would precipitate at given the Ksp and the other ion concentration The addition of Ba(NO3)2 would increase the Ba2+ ion concentration in the mixture. The common ion effect would cause BaF2 to precipitate rather than CuF2.
Suppose that a research technician wants to separate an aqueous mixture of CuF2 and BaF2 (Ksp = 3.0 × 10−6) by precipitating CuF2 from the solution. What should be added to the solution to perform the separation? A.Cu(NO3)2 B.NaF C.Ba(NO3)2 D.H2O
D.different compounds, because SO32− has two more electrons and a different bonding configuration If the same compound/identical chemical species must have the same elemental composition, the same number of electrons, and the same orbital bonding configuration. The net charge of a structure is equal to the sum of all charges present. *DRAW LEWIS*
The anion SO32− and sulfur trioxide, SO3, have the same elemental composition. These two chemical species are: A.the same compound, because both have the same elemental composition. B.the same compound, because both have the same number of electrons and bonding configuration. C.different compounds, because the atoms in SO32− are held together by ionic bonds. D.different compounds, because SO32− has two more electrons and a different bonding configuration
D.10 **FIRST determine if it should be acidic, basic, or neutral and eliminate all that don't match needs to be basic so eliminates A and B. and said pH does not equal pKa so has to be 10!1
The base dissociation constant Kb for the hydrolysis of an alkali metal cyanide salt is given by the relation: Kb=[OH−][HCN]/[CN−] where [OH-],[HCN], and [CN-] are the molar concentrations of the relevant chemical species. What is the pH of an aqueous solution that is 0.001 M in KCN salt? (Note: Ka ≈ 1 × 10^−9 for HCN, and pH ≠ pKa in this solution.) A.6 B.7 C.9 D.10
B.the rate increases as the catalyst surface area is increased. increasing the surface area of a catalyst increases the rate of the reaction**
The experiment was repeated with 3.0 g of solid MnO2 particles added as an alternative catalyst. When MnO2 was ground to a fine powder, the temperature rose more quickly than when the particles were not ground. The most likely reason for this is that with heterogeneous catalysts: A.the rate increases when the catalyst is oxidized. B.the rate increases as the catalyst surface area is increased. C.the rate decreases due to competing side reactions. D.the rate decreases when the catalyst is insoluble.
C.6.0kRT J/mol ΔGt = kRT log(10^−1/10^−7) ΔGt = kRT log(10^6) = 6kRT
What is the estimated free energy change to transport H+ ions across the cell membrane from the parietal cell cytosol to the stomach lumen at a physiological temperature? (∆Gt=kRT log(Cf/Ci)) A.8.0kRT J/mol B.7.0kRT J/mol C.6.0kRT J/mol D.(1/7)kRT J/mol
B.1.0 × 10^−8 M Kw = [H+][OH−] = 1.0 × 10^−14 M^2 Since the pH is 6: [H+] = 10^-6 = 1 x 10^-6 to find [OH-]: [OH−] = Kw/[H+] = 1.0 × 10^−14 / 1 x 10^-6 = 1.0 × 10^−8 M
What is the molar concentration of hydroxide in the duodenum (pH 6.0), where neutralization of the gastric acid leaving the stomach begins to take place? A.1.0 × 10^−14 M B.1.0 × 10^−8 M C.1.0 × 10^−7 M D.1.0 × 10^−6 M
C.2.4 ATA PO2 = 0.8 x (3ATA) = 2.4 ATA
What is the partial pressure of O2 in a 3-ATA multiplace chamber filled with 80% O2 and 20% N2? A.0.2 ATA B.0.6 ATA C.2.4 ATA D.3.0 ATA
E° = SLOPE = Δy/Δx = 2.4 Ve-/2e- = +1.2V
What is the standard potential E° for the half-reaction below? ClO3−(aq) + 3H+(aq) + 2e− → HClO2(aq) + H2O(l) A.+2.4 V B.+1.2 V C.+0.3 V D.−0.6 V
D.250 mL 0.075 g x (100mg/1g) x (1mL/0.3 mg) = 250 mL
What volume of the solutions tested would contain 0.075 g of oxytocin monoacetate? (Given 0.3mg of solution) A.0.022 mL B.0.25 mL C.23 mL D.250 mL
A.aluminum. **find moles of each and use mole ratio FOR AlCL3 to find out how many moles of AlCl3 can be produced from each**** 2g Aluminum x (1 mol Al/27 g Al) x (2 mol AlCl3 / 2 mol Al) = 1/14 0.5 L CuCl2 x (0.5 mol / 1 L) x (2 mol AlCl3 / 3 mol CuCl2) = 0.5 / 3 = 0.15 *TABEL INDICATED CONCENTRATION OF CuCl2 = 0.5 M therefore, aluminum is the limiting reagent
When 2 g of aluminum foil is added to 500 mL of the CuCl2 solution indicated in Table 1, the following reaction takes place: 2 Al(s) + 3 CuCl2(aq) → 2 AlCl3(aq) + 3 Cu(s) The limiting reactant is: A.aluminum. B.copper. C.copper(II) chloride. D.aluminum chloride
B.S atom in Cys-247
When Reaction 1 occurs, the atom acting as the reducing agent is the: A.H atom in Cys-247.[3%] B.S atom in Cys-247 C.S atom in S2O32−. D.O atom in S2O32−
A.N2 because there are more moles of N2. When two gases at the same temperature and pressure are compared, the gas with more moles occupies the larger volume.*** Because the masses of both N2 and O2 are equal (1.5 g each), the gas with the lower molar mass has more molecules. Using the periodic table, the molar mass of N2 is calculated to be 28 g/mol, and the molar mass of O2 is 32 g/mol. Therefore, the N2 gas has more moles and occupies a larger volume.
Which gas would occupy more volume at a constant temperature and pressure, 1.5 g of N2 gas or 1.5 g of O2 gas? A.N2 because there are more moles of N2. B.O2 because its molecules are larger. C.Neither gas occupies any volume. D.Both gases occupy equal volumes
B.CH3COOH(aq) and CH3COONa(aq) weak acid and conjugate base need to be present for a buffer (Cannot be a strong acid, because its conjugate would not affect the pH of a solution)
Which of the following compound pairs, dissolved into solution at equal concentrations, will function as a buffer? A.HNO3(aq) and NaNO3(aq) B.CH3COOH(aq) and CH3COONa(aq) C.NaBr(aq) and NaCN(aq)[2%] D.NaOH(aq) and NaCl(aq)
D.Liquid water initially at 274 K and 6.50 mb will boil at the Spirit location. **MORE CAREFUL****** c is wrong bc is at triple point
Which of the following conclusions can be made based on Figure 1 and the data in Table 1? A.Liquid water initially at 280 K and 15.0 mb will remain liquid at the Viking I location. B.A block of ice at the Pathfinder location will sublimate when heated to 274 K. C.Water vapor released into Mars' average conditions will condense and then freeze. D.Liquid water initially at 274 K and 6.50 mb will boil at the Spirit location.
D. when binds = becomes octahedral** Transition metals generally form complexes with two, four, or six coordinate bonds. Therefore, the geometry of the coordinate covalent bonds will typically be linear (two bonds), tetrahedral or square planar (four bonds), or octahedral (six bonds).
Which of the following depicts iron's coordination geometry when oxygen is bound to heme b in hemoglobin?
B.[Ne]3s^23p^6 Ca2+ ion = 18 electrons**** ION not anion
Which of the following is the electron configuration of a Ca2+ ion? A.[Ne]3s^2 B.[Ne]3s^23p^6 C.[Ne]3s^23p^64s^1 D.[Ne]3s^23p^64s^2
C.Trigonal bipyramidal
Which of the following molecular geometries could describe a compound with a central atom that is dsp3 hybridized? A.Tetrahedral B.Octahedral C.Trigonal bipyramidal D.Square planar
A.C2H4Br2 atoms involved in hydrogen bonding must have small atomic radii, and are essentially limited to fluorine, oxygen, and nitrogen.** Br = super big so will not form hydrogen bonds
Which of the following molecules is unable to form hydrogen bonds with water? A.C2H4Br2 B.C3H9N C.C9H18O2 D.C2F
C.Cl(g) + energy → Cl+(g) + e− Because halogens have a lower first ionization energy than their neighboring noble gases, and because Cl is larger and farther down the halogen group than F, the first ionization of Cl will require the smallest amount of energy of the given reactions. The first ionization energy is the energy required to remove the first, most loosely bound valence electron from a neutral atom. The first ionization energy tends to increase with increasing atomic number moving across a period and decrease moving down a group on the periodic table.
Which of the following reactions requires the smallest amount of energy to remove a valence electron (e−)? A.F(g) + energy → F+(g) + e- B.Ne(g) + energy → Ne+(g) + e− C.Cl(g) + energy → Cl+(g) + e− D.Ar(g) + energy → Ar+(g) + e−
A.I and II only 6.022 × 10^23 amu = 1 mol amu = 1 g** a 96.11 g sample of (NH4)2CO3 will contain 1 mole (6.022 × 1023 units) of (NH4)2CO3 molecules (Number II). 96.11 amu of (NH4)2CO3 refers only to a single molecule of (NH4)2CO3, which does not contain the same mass as a mole of (NH4)2CO3 molecules (Number III)
Which of the following statement(s) is(are)consistent with the molar mass of ammonium carbonate? I. 1.00 mol of (NH4)2CO3 contains 96.11 g of mass. II. 96.11 g of (NH4)2CO3 contains 6.022 × 1023 (NH4)2CO3 molecules. III. 96.11 amu of (NH4)2CO3 contains 1.00 mol (NH4)2CO3. A.I and II only B.I and III only C.II and III only D.I, II, and III
D.Fe(NO3)3 and NaI do not affect the heat of the reaction The decomposition of H2O2 is an exothermic reaction. No matter how long the decomposition takes, the reaction will produce a certain amount of heat per mole of reactants. This means that the identity of the catalyst does not affect the heat of the reaction. Therefore, the reaction using Fe(NO3)3 as the catalyst will result in the same change in temperature as the reaction using NaI as a catalyst, assuming the same amount of H2O2 is used. ***A catalyst does not change the amounts of the products produced or the enthalpy (heat) of the reaction
Which of the following statements explains why the change in temperature of the H2O2 decomposition reaction using Fe(NO3)3 is approximately the same value as the change in temperature using NaI? A.Fe(NO3)3 stabilizes the transition state more than NaI. B.Fe(NO3)3 results in a faster reaction rate than NaI. C.Fe(NO3)3 and NaI are both homogeneous catalysts. D.Fe(NO3)3 and NaI do not affect the heat of the reaction
D.IMP most effectively potentiates Asp **look at ratio!! Thr (40--> 160) but is only 1:4 ratio Asp (1-->60) and is a 1:6 ratio, therefore IMP most effectively potentiates Asp.
Which of the following statements is true concerning the results shown in Figure 3? A.For the compounds potentiated by IMP, the extent of potentiation is five-fold. B.For the compounds potentiated by IMP, the extent of potentiation is equal. C.IMP most effectively potentiates Thr. D.IMP most effectively potentiates Asp
B.I and II only Sigma bonds are lower in energy and more stable than pi bonds, and therefore have a higher dissociation energy sigma = higher dissociation energy, pi = smaller dissociation energy I. correct pi bonds are stronger than C-O bonds II. correct pi bonds are more stable than sigma bonds III. wrong
Which of the following statements is true regarding the bonds in the tastant molecule L-methionine? I. The pi bond in C=O has a smaller dissociation energy than the sigma bond. II. The C=O bond is stronger than the C-O bond. III. The pi bond in C=O is more stable than the sigma bond. A.I only B.I and II only C.II and III only D.I, II, and III
A. Adding dilute nitric acid ** Do le chatliers principle first **goal is to remove F- from solution, so we need to reach it and first decide how to do that F- is a basic ion and will be most soluble with acid and therefore remove it from solution
Which of the following will increase the amount of CuF2(s) that dissolves in water and raise the Cu2+(aq) concentration in the solution? (Note: Cu(OH)2 has a Ksp = 2.2 × 10−20.) CuF2(s) ⇄ Cu2+(aq)+2 F−(aq)) A.Adding dilute nitric acid B.Adding dilute sodium hydroxide C.Diluting the solution with aqueous potassium fluoride D.Evaporating some solution to decrease the solution volume
C.It is the cathode and PbSO4 is reduced at its surface. LOOK AT FIGURE, electrons flow from anode to cathode therefore Pb is the cathode!!!!!
Which statement correctly describes the Pb electrode when the lead storage battery is charging as shown in Figure 1? A.It is the anode and PbSO4 is oxidized at its surface B.It is the anode and H2SO4 is reduced at its surface. C.It is the cathode and PbSO4 is reduced at its surface. D.It is the cathode and H2SO4 is oxidized at its surface
B.No, because ΔG°, ΔH°, and ΔS° are independent of the reaction rate ***catalysts effect reaction rate but do not change ΔG°, ΔH°, and ΔS, and T
Would changes in the van 't Hoff plot be observed if the reaction rate were increased by adding a catalyst during the experiment? A.No, because the initial concentration of acetic acid does not change B.No, because ΔG°, ΔH°, and ΔS° are independent of the reaction rate C.Yes, because the reaction rate and ΔG° depend on temperature D.Yes, because spontaneity depends on the reaction rate
A.No, because water is one of the products produced when the battery is discharged. whenever dealing with batteries, remember that you are probably looking at half reactions** Le chatlier's says as HSO4- is issued, HSO4- decreases
Would the concentration of H2SO4 remain constant as a lead storage battery is discharged? A.No, because water is one of the products produced when the battery is discharged. B.Yes, because PbSO4 increases as the battery is discharged. C.No, because the SO42- ions are oxidized in the reaction. D.Yes, because the H+ ions are not oxidized or reduced in the reaction
A.7.2 moles 250 mL x (1L / 1000 mL) x (4.8 mol ClO3-/1L) x (6 mol electrons/ 1 mol ClO3-) = 7.2 mol
3 H2O + 5 ClO3− + 3 I2 → 5 Cl− + 6 IO3− + 6 H+ Consider the reaction of iodine with ClO3− under acidic conditions, as shown above. If 6 moles of electrons are required to reduce 1 mole of ClO3−, how many moles of electrons are required to completely reduce all the ClO3− ions present in 250 mL of a 4.8 M ClO3− solution? A.7.2 moles B.6.0 moles C.4.8 moles D.1.2 moles
B.higher, because the vapor pressure of briny water is lower than the vapor pressure of pure water. VP is decreased, so boiling point must increase***
Compared to the boiling point of a sample of pure water on Mars, the boiling point of a sample of briny water under the same atmospheric conditions would be: A.lower, because the vapor pressure of briny water is higher than the vapor pressure of pure water. B.higher, because the vapor pressure of briny water is lower than the vapor pressure of pure water. C.lower, because the vapor pressure of briny water is lower than the vapor pressure of pure water. D.higher, because the vapor pressure of briny water is higher than the vapor pressure of pure water
B.2,500 ng *BALANCE FIRST find limiting reactant by moles of Ca3(C6H5O7)2 from each = 5nmol 5nmol x 500ng/nnmol = 2,500 ng Ca3(C6H5O7)2
Given the unbalanced equation (Reaction 1) and the molecular weight of calcium citrate (498.5 g/mol), if 15 nmol of calcium oxalate is mixed with 15 nmol of potassium citrate, what is the approximate theoretical yield of calcium citrate? A.1,250 ng B.2,500 ng C.3,750 ng D.7,500 ng
C.increase. CuF2(s) ⇄ Cu2+(aq)+2 F−(aq) ***the CH3NH2 reacts with the Cu2+ formed, which causes more CuF2(s) to dissolve in order to replace the Cu2+ that was removed
If excess methylamine (CH3NH2) is added to a saturated aqueous CuF2 solution, the amount of CuF2 that dissolves will: (CuF2(s) ⇄ Cu2+(aq)+2 F−(aq)) A.remain the same. B.decrease. C.increase. D.be unrelated to the amount of CH3NH2
B.MgBr2 < MgCl2 < NaBr < NaCl ELECTRONEGATIVITY TRENDS ------> LARGE ^ | |
The bonds of four salts (MgBr2, NaCl, MgCl2, and NaBr) are evaluated for ionic character based on electronegativity differences between atoms. What is the expected order of these four salts if listed according to bond character from the least ionic character to the greatest ionic character? A.NaBr < NaCl < MgBr2 < MgCl2 B.MgBr2 < MgCl2 < NaBr < NaCl C.NaCl < NaBr < MgCl2 < MgBr2 D.MgBr2 < MgCl2 < NaCl < NaBr
C.S2Cl2 Atomic radius trend = ---> small ^ |
The chemical structures of sulfur compounds H2S, SF6, S2Cl2, and S4N4 each contain only single (sigma) bonds. The compound that contains the longest bond between sulfur and an atom of another element is: A.H2S B.SF6 C.S2Cl2 D.S4N4
B.H3SiO4− The conjugate of an acid (or base) is the species that the acid (or base) becomes after losing (or gaining) one proton. An acid (or base) and its conjugate have chemical formulas that differ by only one proton
The conjugate acid of the dihydrogen orthosilicate anion (H2SiO42−) is: A.HSiO43− B.H3SiO4− C.H4SiO4 D.H3O+
C.Replacing the catalyst with potassium iodide In the sodium iodide-catalyzed decomposition of H2O2, I− ions must collide with H2O2 for the catalyzed reaction to occur. Changing the catalyst's cation from Na+ to K+ does not change the concentration of I− or the concentration of H2O and therefore will not change the frequency of collisions in the reaction. (Choice A) Adding an inhibitor to the reaction decreases the frequency of collisions A, which will decrease or halt the reaction and thereby change the results in Figure 2. (Choice B) Increasing the concentration of H2O2 from 3% to 30% will increase the frequency of the collisions A in the reaction, which will increase the rate of the reaction and the amount of heat produced. (Choice D) Increasing the initial temperature of the reaction T will result in a greater number of molecular collisions with an energy greater than Ea. This will increase the rate of the reaction and change the value of ΔT because the initial temperature is changed
The results in Figure 2 would most likely NOT be affected by which of the following changes to the experiment? A.Adding a sodium phosphate inhibitor B.Using 30% H2O2 C.Replacing the catalyst with potassium iodide D.Heating the reaction to 35°C
D.Periodically measure the amount of OH− produced by titrating the beaker contents with HCl. In a good experimental design, the method of measurement must not alter the experimental outcome **adding HCl would alter the experimental outcome!!!! When determining the corrosion rate of the magnesium disks, the experimental technique cannot affect the outcome (ie, the corrosion rate) or it will skew the results. HCl is a strong acid and reacts with magnesium metal to form H2 gas and aqueous MgCl2 (which dissociates into Mg2+ and 2 Cl− ions) according to the equation: Mg(s) + HCl(aq) → Mg2+(aq) + 2Cl−(aq) + H2(g)
Throughout the experiment, researchers monitored the amount of magnesium that dissolved at various time points. Which of the following is NOT a valid test for the rate of magnesium corrosion? A.Periodically measure the volume of H2 gas evolved from the reaction. B.Periodically measure the mass of the magnesium disks. C.Periodically measure Mg2+ concentration in the SBF using elemental analysis techniques. D.Periodically measure the amount of OH− produced by titrating the beaker contents with HCl.
D.10 mL 2.6 x 10^-6 mol x (100 mol recovered /80 mol recovered) x (1067 g / 1 mol) x (1000 mg / 1 g ) x (1 m L/0.3 mg)
What approximate volume of the oxytocin solution with the 10 mM Zn2+ additive was analyzed if 2.2 × 10−6 moles of oxytocin acetate (MW = 1067 g/mol) were recovered from the sample after 4 weeks at 50 °C? A.9 μL B.900 μL C.2 mL D.10 mL
C.HPO42− and NH4+ H2PO4−⇄HPO2−4+H+ pKa = 6.8 At a pH of 8.0, HPO42− will be the dominant species in the phosphate buffer because the pKa of H2PO4− is 6.8, which is less than 8. Likewise, consider the equilibrium: NH4+⇄NH3+H+ pKa = 9.1 In this case, the acidic NH4+ will be the dominant species in the ammonia buffer because the pKa of NH4+ is 9.1, which is greater than 8.
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−⇄HPO2−4+H+ pKa = 6.8 NH4+⇄NH3+H+ pKa = 9.1 A.H2PO4− and NH4+ B.H2PO4− and NH3 C.HPO42− and NH4+ D.HPO42− and NH3
D.Water has a relatively high surface tension Because oxygen is more electronegative than hydrogen, the bonding electron pairs are more tightly drawn to oxygen. This property results in the oxygen atom having a partial negative charge whereas the hydrogen atoms have a partial positive charge, allowing interactions with other charged molecules (Choice B). The bent geometry of water contributes to its polarity by grouping positive charges at one end of the molecule and negative charges at the other. The charged regions of a water molecule are attracted to opposite charges on other polar compounds (Choice A). Water's small size allows efficient formation of a hydration shell around solutes. This process acts to evenly distribute and isolate solute particles (Choice C). **water does have a high surface tension, but it does not explain water's ability to act as a solvent
Which of the following does not explain water's ability to act as a solvent? A.Water has the geometry of a bent molecule. B.Hydrogen is less electronegative than oxygen. C.Water is a relatively small molecule. D.Water has a relatively high surface tension
A. Adding more sodium citrate pH=pKa+log([A−]/[HA])*** Accordingly, the pH of a buffered solution depends on the concentration ratio of acid to conjugate base. Adding more acid will decrease the pH and adding more base will increase the pH. In Experiment 1, the citrate buffer is made of citric acid [HA] and sodium citrate [A−]. Adding more sodium citrate will increase the pH of the solution. The passage states that oxytocin is more stable at a pH of 4.5, and Figure 1 shows that at the higher pH of 6.5 (water), less oxytocin was recovered
Which of the following experimental changes will decrease the percent recovery of oxytocin in Experiment 1? A.Adding more sodium citrate B.Decreasing the initial concentration of oxytocin C.Cooling the samples for 4 weeks D.Increasing the buffer concentration
D. change in temperature is measure by ΔH since ΔH is negative = exothermic, heat is released and mixture gets hot (LINEAR INCREASE ON GRAPH)
Which of the following graphs depicts the expected change in temperature of the reaction mixture over the course of the reaction described in the passage?