Gen chem 2 ___1. The enthalpies of vaporization of the liquids diethyl ether water and mercury are 26.0 40.7 and 59.3 kJ/mol respectively. Which liquid has the strongest intermolecular forces? a. diethyl ether b. water c. mercury d. don’t know ___2. Which of these statements is not true? a. The vapor pressure of a solution increases with increasing temperature b. The boiling point of a solution increases with increasing pressure of the surroundings c. Doubling the quantity of a solution doubles its vapor pressure at fixed temperature d. Vapor pressure is an intensive property of a solution ___3. One beaker under a bell jar is half-filled with seawater and the other beaker is three-quarters filled with pure water. Which beaker will eventually overflow? a. seawater b. pure water c. neither beaker will overflow ___4. Which aqueous solution has the highest evaporation rate at 25 oC? a. 0.1 M KCl b. 0.2 M Na2SO4 c. 0.2 M NaCl d. 0.2 M MgCl2 ___5. The vapor pressure of an aqueous solution of non-volatile glucose is 24.90 torr at 25 oC. The vapor pressure of pure water at 25 oC is 25.76 torr. What is the mole fraction of glucose in the solution? a. 0.967 b. 0.033 c. 1.03 ___6. Which gas is most soluble in water? a. Ar b. O2 c. NH3 d. N2 ___7. How many independent data are needed to calculate the lattice energy of KBr from a Born-Haber cycle? a. 2 b. 3 c. 4 d. 5 ___8. For which compound is it least difficult to separate the ions? a. CaF2 b. NaF c. LiF d. MgF2 ___9. Which cation has the most negative heat of hydration? a. Rb b. K c. Na d. Li ___10. In the following system: NaOH (s) H2O (l) = NaOH solution (aq) heat a. NaOH solubility is independent of temperature b. NaOH solubility increases with increasing temperature c. NaOH solubility increases with decreasing temperature d. no solution is formed at any temperature ___11. Which statement concerning the fractional distillation of a solution of two volatile non-ionic liquids is not true? a. The substance with the lower boiling point has a higher concentration in the vapor than the liquid b. The substance with the higher vapor pressure has a higher concentration in the vapor than the liquid c. The mole ratio of the two substances in the vapor is not the same as it is in the liquid d. When the vapor at any stage of the distillation is condensed the resulting distillate has the same composition as the original solution ___12. What is the molality of a solution produced by dissolving 14.40 g of LiCl (42.39 g/mol) in water to make 0.104 L of solution with a density of 1.102 g/mL? a. 0.340 m b. 3.39 m c. 3.74 m ___13. Which is the solvent in a mixture of 208 g BaCl2 and 90.0 g of water? a.BaCl2 b. H2O ___14. What is the molality of the mixture in Question 13 above? a. 0.111 b. 1.11 c. 11.1 ___15. At a certain temperature the vapor pressures of benzene and 1-chlorooctane are 75 torr and 22 torr respectively. What is the vapor pressure of a solution of these two substances if the mole fraction of benzene is 0.30? a. 38 torr b. 75 torr c. 22 torr d. none of these ___16. What is the mole fraction of benzene in the vapor above the solution in Question 15? a. 1.2 b. 0.9 c. 0.6 d. 0.3 ___17. Addition of 30.0 g of solid substance X to 90.0 g of water changes the boiling point from 100.1 to 102.2oC. Find the molar mass (g/mol) of X (Kb for water 0.51Co/molal). a. 80 b. 8.0 c. 800 d. none of these ___18. Calculate the freezing point (oC) of a solution containing 64.0 gm of methanol (CH3OH) in 1.000 kg water (Kf for water is 1.86Co/molal). a. 3.72 b. 0.372 c. -3.72 d. -0.372 Note: Midterm Exam 1 will have 25 Questions ___19. What is the lowest possible freezing point (oC) of a solution of 14.2 gm Na2SO4 in 80.0 g water (Kf for water is 1.86Co/molal)? a. 0.69 b. -6.9 c. -0.69 d. 6.9 ___20.The total molar concentration of all solute species in a tissue cell is 5.6 x 10-2M. Calculate the osmotic pressure (atm) across the cell membrane at 37oC (the ideal gas constant R is 0.0821 Liter atm/K mol; assume all the cell contents are molecular). a. 0.14 b. 1.4 c. 14 d. none of these ___21. The vapor pressure of pure water is 149 torr at 60oC. The vapor pressure of water above a solution containing 4.5 mole of water and 0.5 mole of non-volatile glucose C6H12O6 is 126 torr at 60oC. Is the solution obeying Raoult’s Law? a. Yes b. No c. insufficient information ___22. Calculate the molal concentration of CaCl2 in a solution containing 2.22 g of CaCl2 and 9.00 g of water. a. 2.22 x 10-3 m b. 2.22 m c. 4.05 m d. 4.05 x 10-3 m ___23. A solution made by dissolving 0.25 g of non-electrolyte substance X in 40.0 g of CCl4 boiled at a temperature 0.357 o C higher than for pure CCl4. What is the molar mass (g/mol) of substance X (Kb for CCl4 is 5.02 oC/molal)? a. 44 b 88 c 176 d. 22 ___24. The osmotic pressure of 100.0 mg of non-electrolyte substance Y in 10.0 mL solution is 2.88 torr at 27 oC. Calculate the molar mass (g/mol) of Y. a. 65 000 b. 64.5 c. 200 d. some other value ___25. At a certain point in time the rate of disappearance of A in the reaction A ? 2B is 0.064 M min-1. The rate of appearance of B at that time is equal to a. 0.032 M min-1 b. 0.064 M min-1 c. 0.128 d. 0.128 M min-1 MT1 has 25 questions ___26. Give the overall order of the reaction with rate law rate = k[A][B]2 a. zero b. first c. second d. third ___27. The units of the rate constant k in Question 26 above with time measured in seconds are a. Msec-1 b. sec-1 c. M-1sec-1 d. M-2sec-1 ___28. A reaction is second order in [A]. Therefore doubling [A] a. halves the rate b. doubles the rate c. quadruples the rate ___29. Reactions with small rate constants have a. short half-lives b. long half lives ___30. Calculate the half-life of a reaction with k = 69.3 min-1 a. 0.01 min b. 0.10 min c. 6.93 min d. 0.693 min ___31. The decomposition of formaldehyde in water has a rate constant of 2 M-1sec-1 at 75 oC. How long does it take for a 0.2 M solution of formaldehyde to decrease to 0.1 M at 75 oC? a. 2.5 min b. 2.5 sec c. 0.36 sec d. don’t know ___32. Kinetic data were obtained for reaction (1) at 550 K. 2CH4(g)® C2H4(g) 2H2(g) (1) Experiment number [CH4]o M Initial rate Mmin-1 ___________________________________________________________ 1 0.100 4.0 x 10-2 2 0.200 16.0 x 10-2 3 0.400 64.0 x 10-2 Calculate the rate constant of the above reaction at 550 K. a. 4.0 M-1sec-1 b. 4.0 Mmin-1 c. 4.0 min-1 d. 4 M-1min-1 ___33. For most reactions a plot of ln k versus 1/T where k is the rate constant at different absolute temperatures T a. is non-linear b. is linear with a positive slope c. is linear with a negative slope d. has zero slope __ 34. The following exothermic reaction profile illustrates a mechanism consisting of a. three steps b. a slow step followed by a fast step c. a fast step followed by a slow step d. one step free energy | [sketch your own profile] kJ | | | | | | |__________________________________ reaction? ___35. For which reaction is the rate constant least sensitive to temperature changes? a. reaction A activation energy 56 kJ/mole b. reaction B activation energy 1 kJ/mole c. reaction C activation energy 112 kJ/mole d. the rate constants respond in the same way ___36. Catalysts a. increase the activation energy of a reaction b. decrease the activation energy of a reaction c. don’t affect the activation energy of a reaction ___37. The experimental factor A in the Arrhenius equation k = Aexp(-E/RT) reflects a. the magnitude of the activation energy b. the overall reaction order c. the orientation of the reactants in the activated complex for the reaction ___38. Inhibitors a. are mistaken for reactants b. block the catalyst site c. decrease the rate of a catalyzed reaction d. a b and c ___39. Reactions involving heterogeneous catalysis are subject to a. rate saturation b. deactivation by reactant impurities c. rate limiting product desorption d. a b or c ___40. A complete description of an equilibrium system must include a. a written form of the equilibrium b. the temperature c. the magnitude of the equilibrium constant d. a b and c ___41. A chemical equilibrium 2A = B has a forward rate constant kf = 10 M-1s-1 and a reverse rate constant kr = 5 s-1. If the system has [A] = 0.10 M at equilibrium what must the concentration of B be at equilibrium? a. 20 b. 2.0 c. 0.2 d. 0.02 ___42. A particular equilibrium system has Kc = 5.6 x 10-4 at 25 oC. We say the system ‘lies to the a. left b. right ___43. The equilibrium constant K4 for reaction (4) is given by A B= C K2 (2) D= C K3 (3) A B= D K4 (4) a. K4 = K2K3 b. K4 = K2/K3 c. K4 = K3/K2 ___44. Adding reactant B to equilibrium (2) in Question 43 a. decreases the concentration of A b. decreases the concentration of C c. increases the concentration of A __45. The equilibrium constant of the following system is given by 2BaSeO3(s) O2(g)= 2BaSeO4(s) a. Kc = BaSeO4(s)]/[O2(g)][BaeSO4(s)] b. Kc = BaSeO4(s)]2/[O2(g)][BaSeO4(s)]2 c. Kc = 1/[O2(g)] d. [O2(g)] __46. Gaseous HF is formed from a mixture of H2 and F2. If [H2] = [F2] = 2.0 M and Kc = 115 what is the equilibrium concentration of HF? a. 0.85 M b. 1.69 M c. 2.85 M d. 3.37 M _ 47. Equilibrium data at a particular temperature for the reaction 2 NO2 (g) F2 (g) = 2 NO2F (g) are as follows: [NO2F (g)] = 2 x 10-3 M [NO2(g)] = 2 x 10-2M and [F2 (g)] = 4 x 10-4 M. Calculate Kc. a. 2.5 b. 5 c. 25 d. 2.5 x 10-3 __48. An equilibrium system 2 A = B C with Kc = 5 at 35 oC is set up with [A] = [B] = [C] = 2.0 M. The system will shift to make a. more B b. more C c. more B and more C d. more A __49. Compound X comes to equilibrium with another molecular form Y when X is dissolved in water. At 50 oC the equilibrium constant Kc is 5. Calculate the equilibrium concentration of Y if 1.000 mol of X is dissolved in 500 mL of water at 50 oC. a. 0.33 M b. 1.80 M c. 2.00 M d. 1.67 M __50. Which of these substances is not a strong acid when dissolved in water? a. HCN b. HBr c. H2SO4 d. HNO3 __51. A solution with pH = 8.5 has [OH¯] equal to a. 3.16 x 10-6 M b. 1.00 x 10-7 M c. 3.16 x 10-9 M d. none of these __52. Which 0.1 M aqueous solution is weakly basic? a. HBr b. CsOOCCH3 c. KOH d. NaBr __53. Which of these anions can only behave as a base when dissolved in water? a. BrO¯ b. HPO4¯ c. HCO3¯ d. b and c __54. The pKAvalues of the acids HX HY and HZ are 3.4 4.4 and 5.4 respectively. The strongest acid of these three is a. HX b. HY c. HZ d. don’t know __55. The triprotic acid H3XO4 has KA1 = 2.0 x 10-4. Therefore KB3for H2XO4¯ is a. 1.0 x 10-14 b. 5.0 x 10-7 c. 5.0 x 10-11 d. 1.0 x 10-7 __56. The pH of the product solution made by precisely titrating aqueous 0.05 M ammonia (KB = 1.8 x 10-5) to the endpoint with 0.05 M HCl is a. 1.0 b. 7.0 c. less than 7.0 d. more than 7.0 __57. Which indicator is suitable for detecting the true endpoint of the titration in Question 7? a. bromophenol blue (yellow ? bluish purple pH 3 ? 4.6) b. methyl red (red ? yellow pH 4.2 ? 6.3) c. cresol red (yellow ? red pH 7.2 ? 8.8) __58. The pH of 2.0 x 10-2 M ammonia solution (pKB = 4.74) is a. 3.37 b. 3.22 c. 10.63 d. 10.81 __59. Which of the following solutions is not a buffer solution? a. NaH2PO4/Na2HPO4 b. NH4Br/NH3 c. HBr/NaBr d. all are buffers __60. The pH of a solution containing 0.1 M NH3 (KB= 1.8 x 10-5) and 0.2 M NH4NO3 is a. 4.74 b. 8.96 c. 9.26 d. none of these __61. Ammonia is added to the solution in Question 11 and its pH a. decreases b. increases c. stays the same __62. Adding NaOH to an NH3/NH4Cl buffer solution a. decreases the concentration of NH4 b. increases the concentration of NH4 c. decreases the concentration of NH3 d.none of these __63. What is the pH of a 0.115 M aqueous solution of morphine (pKB = 5.79)? a.10.62 b. 3.36 c. 7.00 d. -10.62 __64. In which solution is CaCO3 (s) most soluble? a. 0.010 M Ca(NO3)2 b. 0.010 M Na2CO3 c. 0.001 M Na2CO3 d. 1 x 10-6M Ca(NO3)2 CCAAB CDBDC DBBCA CACBB BBBAC DDCBA BDC_B BCDDD CABAC BCCDA ABAAC CBDCB BAAD
