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SPRING SEMESTER REVIEW
AP CHEMISTRY
1. Which of the following changes will change the position of equilibrium?
(a) allow more time to pass
(c) add a catalyst
(b) remove some products
(d) all of these
2. At equilibrium, [PSCl3] = 1.00 M, [PCl3] = 7.8 x 10-4 M, while K = 1.3 x 10-29. Calculate [S8].
8PSCl3 (g)  8PCl3 (g) + S8 (g)
(a) 1.00 M
(b) 1.6 x 10-26 M
(c) 9.5 x 10-5 M
(d) 94.88 M
3. What is the equilibrium constant for the reverse reaction of the previous problem?
(a) 1.3 x 10-29 (b) 7.7 x 1028
(c) 4.1 x 10-15
(d) 1.3
4.
BaS(s) + 2O2(g) <--> BaSO4(s)
Which one of the following is the correct expression for Kc for this above equation?
(a) 1/[O2]2
(b) [BaSO4] / [BaS] [O2]2 (c) [O2]2
(d) [BaS] [O2]2 / [BaSO4]
5. A 2.21L vessel was found to contain 0.0418 mol of CO 2, 0.0281 mol of CO and 0.00889 mol of O 2. Is the system at
equilibrium for the following reaction? If not, which direction must the reaction proceed to achieve equilibrium?
2CO2(g) <--> 2CO(g) + O2(g) Kc = 1.2 x 10-13
(a) yes
(b) no, to the right
(c) no, to the left
(d) not enough information given
For questions #6-12, use the following equation:
Ni(s) + 4CO(g) <--> Ni(CO)4(g) The reaction is exothermic.
For each of the following questions #6-12, how would the following changes affect the above reaction if it is at equilibrium?
Use the answer choices below:
(a) Shifts right
(b) shifts left
(c) no change
(d) can’t tell from the information given
6. Add more Ni?
7. Add more CO (g)
8. Add Neon (g)
9. Remove Ni(CO)4 (g)
10. Cut volume by ½
11. Increase Temperature
12. Add a catalyst
13. For which one of the following reactions is Kc equal to Kp?
(a) H2(g) + Cl2(g) <--> 2HCl(g)
(c) N2O4(g) <--> 2NO2(g)
(b) 2SO3(g) <--> 2SO2(g) + O2(g)
(d) C(s) + CO2(g) <--> 2CO(g)
14. Which of the following does NOT represent an acid followed by its conjugate base?
(a) H3O+ / H2O
(b) HCN / CN(c) HCl / Cl(d) HC2H3O2 / OH(e) All are acids followed by their conjugate base
15. The equilibrium constant for the reaction A- + H+ <----> HA is called:
(a) Ka
(b) Kb
(c) 1/Ka
(d) Kw
16. What is the pH of a 10.0 M solution of HNO3?
(a) 10
(b) 1.0
(c) 0
(d) -1.0
(e) none of these
17. Nitrous acid, HNO2, has an ionization constant Ka = 4.0 x 10-4. The pH of a 0.25 M HNO2 solution is:
(a) 2.00
(b) 2.30
(c) 2.70
(d) 3.70
(e) none of these
18. In a solution prepared by dissolving 0.10 mole of an acid HX in enough water to make 1.00 L of solution, the pH is
observed to be 1.35. What is the Ka for this acid?
(a) 2.0 x 10-2
(b) 3.6 x 10-2
(c) 4.5 x 10-2
(d) 5.0 x 10-12
(e) none of these
19. What is the pOH of a 0.10 M solution of Ba(OH) 2?
(a) 13.30
(b) 0.70
(c) 1.00
(d) 13.00
(e) none of these
20. The [OH-] in a 0.50 M pyridine solution (C5H5N; Kb = 1.7 x 10-9) is:
(a) 0.50 M
(b) 2.9 x 10-5 M (c) 1.8 x 10-9 M (d) 3.3 x 10-10 M (e) none of these
21. If Ka for HCN is 6.2 x 10-10, what is Kb for CN-?
a) 6.2 x 10-2
b) 6.2 x 104
c) 1.6 x 10-5
d) 1.6 x 10-23
e) none of these
22. Which of the following substances can be dissolved in water to give a basic solution?
a) NH4Cl
b) NaBr
c) KF
d) NaHSO4
e) KNO3
23. What is the pH of a 1.0 M aqueous solution of NaCl?
a) 7.0
b) greater than 7.0
c) less than 7.0
d) not enough information
24. The common ion effect
a) reduces the dissociation of a weak acid
b) increases the dissociation of a weak acid
c) changes the equilibrium constant for a reaction
d) Has no effect on the dissociation of a weak acid
25. Which of the following combinations in solution CANNOT be a buffer?
a) HNO2/KNO2 b) KCl/HCl
c) NH3/NH4NO3 d) NaH2PO4/H3PO4
e) NaF/HF
26. What is the pH of a solution prepared by mixing 50 ml of a 0.10M solution of HF with 25 ml of a 0.20M solution of NaF?
(The pKa of HF is 3.14)
a) 3.14
b) 10.80
c) 5.83
d) 7.35
e) 12.00
27. What is the pH of a solution that is 0.2M in acetic acid (Ka = 1.8 x 10-5) and 0.2M in sodium acetate?
a) 4.7
b) 9.3
c) 7.0
d) 5.4
e) 8.6
28. What is the molarity of a sodium hydroxide solution if 25.0 ml of this solution reacts exactly with 22.30 ml of 0.253 M
sulfuric acid?
a) 0.113M
b) 0.226M
c) 0.284M
d) 0.451M
e) 0.567M
29. If 100 ml of 0.25M HCl are added to 100 ml of 0.25M NaOH, what is the final pH?
a) 12.70
b) 12.80
c) 1.30
d) 1.20
e) 7.00
Referring to the pH curve below to answer questions #30-32
30. What is the pH at the equivalence point ?
a) 2.2
b) 3.9
c) 7.0
d) 8.2
31. Which of the following is true?
a) A weak acid is being titrated with strong base
b) A strong acid is being titrated with strong base
c) A weak base is being titrated with strong acid
d) A strong base is being titrated with strong acid
32. What is the approximate Ka of the acid used in this titration?
a) 0.005
b) 1.3 x 10-4
c) 1.0 x 10-7
d) 6.3 x 10-9
e) 12.0
33. Which of the following is the net ionic equation for the reaction that occurs during the titration of nitrous acid (HNO 2)
with potassium hydroxide?
a) HNO2 + K+ + OH- ---> KNO2 + H2O
b) HNO2 + H2O ----> NO2- + H3O+
c) HNO2 + KOH ----> K+ + NO2- + H2O
d) HNO2 + OH- ----> NO2- + H2O
e) H+ + OH- ----> H2O
34. A solution of ammonia is titrated with hydrochloric acid. At the equivalence point, phenolphthalein will be what color?
a) colorless b) pink
c) red
d) blue
35. The molar solubility of BaF2 is 7.5 x 10-3 mol/L. What is the value of Ksp for BaF2?
a) 4.2 x 10-7 b) 1.7 x 10-6
c) 8.4 x 10-7
d) 8.7 x 10-2
e) 7.5 x 10-3
36. The Ksp of Ag2CO3 is 8.1 x 10-12. What is the molar solubility (mole/L) of silver carbonate?
a) 1.3 x 10-4 b) 2.9 x 10-6
c) 2.0 x 10-4
d) 2.0 x 10-6
e) 8.2 x 10-12
37. What is the concentration of Al3+ in a saturated aqueous solution of Al(OH)3 (Ksp = 2.0 x 10-32)?
a) 3 x 10-9
b) 7 x 10-9
c) 2 x 10-11
d) 3 x 10-17
e) none of these
38. The Ksp for BaF2 is 2.4 x 10-5. When 10 ml of 0.01 M NaF is mixed with 10 ml of 0.01M BaNO 3, will a precipitate form?
a) No, because Q is 1 x 10-12 and since it is less than Ksp, no precipitate will form.
b) Yes, because Q is 1 x 10-12 and since it is less than Ksp, a precipitate will form.
c) No, because Q is 1.25 x 10-7 and since it is less than Ksp, no precipitate will form.
d) Yes, because Q is 1.25 x 10-7 and since it is less than Ksp, a precipitate will form.
e) none of the above.
39. Which one of the following processes is endothermic?
a) 2H2(g) + O2(g) ----> 2H2O(g)
b) H2O(g) ----> H2O(l)
c) CH4(g) + 2O2(g) ----> CO2(g) + 2H2O(g)
d) H2O(s) -----> H2O(l)
40. 3N2O(g) + 2NH3(g) -----> 4N2(g) + 3H2O(g) Enthalpy change = -879.6 kJ
What is the heat of formation for N2O in kJ/mole (heats of formation: NH3 = -45.9 kJ/mole and H2O = -241.8 kJ/mole)?
a) +246
b) +82
c) -82
d) -246
41. Given the following heats of combustion: C2H2(g) = -1300 kJ/mole, H2(g) = -286 kJ/mole, C2H6(g) = -1560 kJ/mole,
Calculate the enthalpy change for the following reaction: C2H2(g) + 2H2(g) ----> C2H6(g)
a) -312 kJ
b) -26 kJ
c) +26 kJ
d) +312 kJ
42. A reaction that occurs only when heat is added is best described as
a) exothermic
b) endothermic c) unstable
d) spontaneous
e) stoichiometric
43. Solid zinc oxide, ZnO, has a heat of formation of about -84 Kcal/mole. Select the correct statement for a reaction producing
162.9 grams of zinc oxide.
a) 42 kcal are absorbed b) 81 kcal are absorbed c) 81 kcal are released d) 168 kcal are absorbed e) 168 kcal are released
44. Given the following thermochemical data:
N2O4 (g) ----> 2NO2(g)
∆H = +57.93 kJ
2NO(g) + O2(g) ----> 2NO2(g)
∆H = -113.14 kJ
Determine the ∆Hrxn for the following reaction: 2NO(g) + O2(g) -----> N2O4(g)
a) 171.07 kJ b) -55.21 kJ
c) -171.07 kJ
d) +55.21 kJ
e) -85.54 kJ
45. For which one of the following is the heat of formation equal to zero?
a) O2(s)
b) ice
c) N2(g)
d) F2(s)
e) I2(g)
46. When 0.157 mol NH3 is reacted with excess HCl, 6.91 kJ of energy is released as heat. What is the enthalpy change for this
reaction per mole of NH3?
a) -22.7 J
b) -1.08 kJ
c) -44.0 kJ
d) +22.7 J
e) +44.0 kJ
47. Which statement is FALSE?
a) If a reaction is thermodynamically spontaneous, it may occur rapidly.
b) A fast reaction may be thermodynamically spontaneous.
c) If a reaction is thermodynamically spontaneous, it may occur slowly.
d) If a reaction is thermodynamically spontaneous, it must have a low activation energy.
e) Rate of reaction is a kinetic quantity rather than a thermodynamic quantity.
48. A catalyst
a) is used up in a chemical reaction
b) changes the value of Δ G of the reaction
c) is always a solid
d) does not influence the reaction in any way
e) changes the activation energy of the reaction
49. What is the entropy change of the reaction below at 298K and 1 atm pressure?
N2(g) + 3H2(g) ----> 2NH3(g)
S(J/mol x K)
191.5
130.6
192.3
a) -198.7 J/K b) 76.32 J/K
c) -129.7 J/K
d) 303.2 J/K
e) 384.7 J/K
50. If the entropy change for the reaction below at 298 K and 1 atm pressure is 137 J/K, and S=205 J/mol x K for O 2(g),
what is S for O3(g)?
2O3 ----> 3O2
a) 364 J/mol x K
b) 478 J/mol x K c) 239 J/mol x K
d) -117 J/mol x K
e) -59 J/mol x K
51.Which one on the following reactions has a positive entropy change?
a) H2O(g) ----> H20(l)
b) BF3(g) + NH3(g) ----> F3BNH3(s)
c) 2SO2(g) + O2(g) ----> 2SO3(g)
d) N2(g) + 3H2(g) ----> 2NH3(g)
e) 2NH4NO3(s) ----> 2N2(g) + 4H2O(g) + O2(g)
52. What is Δ G for the reaction below at 25 degrees C?
2C2H2(g) + 5O2(g) ----> 4CO2(g) + 2H2O(l)
Values for Δ Gf for the reactants and products in the above order (in kJ/mole) are: 209.2, 0, -394.4, -237.2
a) -1409 kJ
b) -2599 kJ
c) -1643 kJ
d) -2470 kJ
e) -766 kJ
53. Calculate Δ Gf at 298K for PbCl2(s) from the following information. Δ G for the reaction below is -58.4kJ at 298K.
PbS(s) + 2HCl(g) ----> PbCl2(s) + H2S(g)
Δ Gf (kJ/mol)
-98.7
-95.3
?
-33.6
a) -16.0 kJ/mol
b) -47.6 kJ/mol c) -314.1 kJ/mol d) -36.2 kJ/mol e) -52.3 kJ/mol
54. For the following reaction at 298K, Δ H = -26.88kJ and Δ S = 11.2 J/K. Calculate Δ G for the reaction.
I2(g) + Cl2(g) ----> 2ICl(g)
a) -102 kJ
b) 50.6 kJ
c) -30.2 kJ
d) -50.6 kJ
e) -77 kJ
55. Estimate the temperature at which Δ G = 0 for the following reaction: NH3(g) + HCl(g) ----> NH4Cl(s)
For the reaction, delta H = -176 kJ, and delta S = -284.5 J/K
a) 467K
b) 582K
c) 619K
d) 634K
e) 680K
56. A process CANNOT be spontaneous if
a) it is exothermic, and there is an increase in disorder
b) it is endothermic, and there is an increase in disorder
c) it is exothermic, and there is a decrease in disorder
d) it is endothermic, and there is a decrease in disorder
57. Which of the following is a kinetics concept?
a) free energy
b) enthalpy
c) spontaneity
d) reaction mechanism
e) entropy
58. Consider the following reaction NH4Br(s) ----> NH3(g) + HBr (g) The Δ H for the reaction is +188kJ
Which response describes the thermodynamic spontaneity of the reaction?
a) The reaction is spontaneous at all temperatures
b) The reaction is spontaneous only at relatively high temperatures
c) The reaction is spontaneous only at relatively low temperatures
d) The reaction is not spontaneous at any temperatures
e) We cannot tell from the information given
59. What is the reducing agent in following reaction: Cr2O72- + 6S2O32- + 14H+ --> 2Cr3+ + 3S4O62- + 7H20
a) Cr2O72b) S2O32c) H+
d) Cr3+
e) S4O6260. Which substance is the oxidizing agent in the following reaction: Pb + PbO2 + 2H2SO4 --> 2PbSO4 + 2H20
a) Pb
b) H2SO4
c) PbO2
d) PbSO4
e) H2O
61. What is the oxidation number of each sulfur atom in manganese (II) sulfate?
a) -2
b) +3
c) +6
d) -1
e) 0
62. The electrode at which oxidation occurs is called the
a) oxidizing agent
b) cathode
c) reducing agent
d) anode
63. In a galvanic cell, which direction do electrons flow?
a) cathode to anode
b) anode to cathode
64. One volt equals
a) 1 amp x s
b) 1 J/s
c) 96500 C
d) 1 J/C
65. The two electrodes Cr(s)/ Cr3+(aq) and Sn(s)/Sn2+(aq) are combined to afford a spontaneous electrochemical reaction.
The standard reduction potentials in Volts for Cr3+(aq) and Sn2+(aq) are -0.74 and -0.14, respectively. Eº in Volts is
a) +0.88 V
b) -0.88 V
c) +0.60 V
d) -0.60 V
e) +2.50 V
66. The standard reduction potentials in Volts for Ag+ and Ni2+ are +0.80 and -0.28, respectively. Electrons in the cells flow
through the _______ toward the ________.
a) wire, silver electrode
b) wire, nickel electrode c) salt bridge, nickel electrode d) salt bridge, silver electrode
67. The standard reduction potentials in Volts for Pb 2+ and Ag+ are -0.13 and +0.80, respectively. Calculate Eº ( in volts) for
a cell in which the overall reaction in Pb + 2Ag + --> Pb2+ + 2Ag.
a) 0.93
b) 0.67
c) 1.73
d) 1.47
68. Which of the following types of elements is most likely to be good oxidizing agents?
a) alkali metals
b) lanthanides
c) alkaline earth elements d) transition metals
e) halogens
69. A spontaneous electrochemical reaction has
a) delta Gº = 0, Eº = 0 and K>1
b) delta Gº < 0, Eº > 0 and K>1
c) delta Gº > 0, Eº < 0 and K<1
d) delta Gº > 0, Eº < 0 and K>1
e) delta Gº < 0, Eº = 0 and K>1
70. Eº for the following reaction is 0.13 V. What is the value of Δ Gº (in kJ) for the reaction? (F= 96,500 C/mol e-)
Pb(s) + 2H+(aq) --> Pb2+(aq )+ H2(g)
a) -25
b) 25
c) -12
d) 12
71. Consider the half reaction below. What will happen to the voltage of the half cell if the iodate concentration (IO3-) is
increased?
2IO3-(aq) + 10e- + 12H+(aq) --> I2(s) + 6H2O(l) Eº = 1.195V
a) it will increase
b) it will decrease
c) it will not change
72. The standard reduction potentials in volts, for Ag+ to Ag and Fe3+ to Fe2+ are +0.80 and +0.77 respectively. What is the
value of Δ Gº (in kJ) for the reaction? (F= 96,500 C/mol e-)
Ag+(aq) + Fe2+(aq) --> Ag(s) + Fe3+(aq)
a) 2.9
b) -2.9
c) 5.8
d) -5.8
73. Calculate K, the equilibrium constant, for the reaction in #72 at 25ºC. (R = 8.31 J/K*mole)
a) 10.0
b) 2.0
c) 3.3
d) 1.0
74. How many grams of Ca metal could be produced by the electrolysis of molten CaBr 2 using a current of 30.0 amp for
10.0 hours?
a) 22.4 g
b) 448 g
c) 0.0622 g
d) 224 g
75. How long will it take to plate out 2.19 g of chromium metal from a solution of Cr3+ using a current of 35.2 amps?
a) 5.77 minutes
b) 346 minutes c) 115 minutes d) 1.92 minutes
76. Name the following complex ion: [Ni(CN)4]2-
Write balanced net ionic equations for the following reactions:
77. Powdered calcium oxide is added to water.
78. Aqueous solutions of lead (II) nitrate and sodium chloride are mixed.
79. Solid potassium chlorate is heated.
80. Chlorine gas is bubbled into a solution of potassium bromide.