SPRING 2002 Test 3
1. For CdO(s) + SO3(g) => CdSO4(s) ∆H0 = -279.4 kJ and ∆S0 = -118.4 J/ K. What is the
temperature at which Keq is 1.0 x 104?
A. 2163 K
B. 7223 K
C. 1433 K
D. 1983 K
E. 6683 K
Ans. C
2. Under what conditions will the reaction, 2 Cu(s) + O2(g) => 2 CuO(s), be
spontaneous? At 25oC ∆G0 = -130 kJ, ∆H0 = -157 kJ, and ∆S0 = -93.0 J/K.
A. under all conditions
B. under no conditions
C. at high temperature
D. at low temperature
E. This cannot be answered without additional information.
Ans. D
3. Calculate the pH of the solution that results when 30.0 mL of 0.500 M HCOOH is
mixed with 30.0 mL of 0.250 M NaOH. Ka of HCOOH is 1.80 x 10-4.
A. 2.02
B. 2.17
C. 3.74
D. 4.43
E. 9.57
Ans. C
4. Choose the correct statements concerning the entropy.
I. As two gases mix, ∆S is positive.
II. Entropy is a thermodynamic property related to the degree of disorder.
III. As temperature in a gas decreases, ∆S is positive.
IV. Molecules in the liquid state have higher entropies than molecules in the gaseous
state.
A. I and III
B. I, II, and III
C. I and II
D. I, II, IV
E. II and III
Ans. C
5. Calculate the pH of the solution that results when 25.0 mL of 0.60 M HF is mixed with
37.5 mL of 0.40 M NaOH. Ka of HF = 7.4 x 10-4.
A. 1.7
B. 8.8
C. 5.7
D. 7.0
E. 8.3
Ans. E
6. Which of the following processes should show the greatest increase in entropy?
A. C6H6(l) + 15/2 O2(g) => 6 CO2(g) + 3 H2O(g)
B. 2 NO2(g) => N2O4(g)
C. C2H4(g) + H2(g) => C2H6(g)
D. BaS(s) + 2 NaNO3(s) => Ba(NO3)2(s) + Na2S(s)
E. This cannot be predicted without additional information.
Ans. A
7. What is ∆G0rxn for N2O4(g) => 2 NO2(g)
∆Gf0 (kJ/mol) 97.8
51.3
A. 149.1 kJ
B. –4.8 kJ
C. –46.5 kJ
D. 4.8 kJ
E. 46.5 kJ
Ans. D
8. For the reaction N2O3(g) => NO(g) +NO2(g) ∆G0 = -4.78 kJ. Calculate Keq at 25oC.
A. 1.023
B. 1.002
C. 1.216
D. 6.884
E. 9.72 x 109
Answer is D
9. Calculate the pH of the solution that results when 25.0 mL of 0.60 M HCl is mixed
with 37.5 mL of 0.40 M NaOH
A. 0.22
B. 0.62
C. 7.0
D. 13.4
E. 13.6
Ans. C
10. Which of the following combinations of ∆H and ∆S will always result in a reaction
being nonspontaneous?
A. ∆H > 0, ∆S < 0
B. ∆H < 0, ∆S > 0
C. ∆H < 0, ∆S < 0
D. ∆H > 0, ∆S > 0
E. cannot determine without temperature
Ans. A
11. Which, if any of the following mixtures will result in a precipitate. You might need
to know that the Ksp for AgCN is 2.2 x 10-16 and that for PbI2 is 7.9 x 10-9.
I. a mixture that is 1.2 x 10-6 M AgNO3 and 2.4 x 10-10 M NaCN
II. a mixture that is 2.3 x 10-4 M Pb(ClO4)2 and 4.6 x 10-3 M KI
A. both will produce precipitates
B. Neither will produce precipitates
C. I will precipitate but II will not precipitate
D. II will precipitate but I will not precipitate
E. More information is required to come to a conclusion.
Ans. C
12. Examine the following half-reactions and select the strongest oxidizing agent among
the substances.
Cr2+(aq) + 2e- => Cr(s) E° = -0.913 V
Co2+(aq) + 2e- => Co(s) E° = -0.28 V
Fe2+(aq) + 2e- => Fe(s) E° = -0.447 V
Sr2+(aq) + 2e- => Sr(s) E° = -2.89 V
A. Cr2+(aq)
B. Co2+(aq)
C. Fe2+(aq)
D. Sr2+(aq)
E. Sr(s)
Ans. B
13. Give the cell notation for a voltaic cell constructed from an iron rod in a solution of
iron(III)chloride as the cathode and a zinc strip in a solution of zinc sulfate as the anode.
A. Zn | Zn2+(aq) || Fe | Fe3+(aq)
B. Zn2+(aq) | Zn || Fe3+(aq) | Fe
C. Fe | Fe3+(aq) || Zn2+(aq) | Zn
D. Zn | Zn2+(aq) || Fe3+(aq) | Fe
E. Fe3+(aq) | Fe || Zn | Zn2+(aq)
Ans. D
14. Which of the following solutions would be described as a buffer solution?
A. 0.25 M CH3COOH and 0.2 M HCl
B. 0.25 M CH3COOH and 0.2 M NaOH
C. 0.15 M NaBr and 0.20 M HBr
D. 0.25 M NH3 and 0.15 M NaOH
E. 0.25 M HCl and 0.10 M NaOH
Ans. B
15. Balance the following equation in acidic solution using the lowest possible integers
for coefficients. What is the coefficient of H2O?
HNO2 + Cr2O72- => Cr3+ + NO3A. 1
B. 2
C. 4
D. 5
E. 6
Ans. C
16. Calculate the pH of the solution formed by mixing 25.0 mL of 0.22 M NH3 with 25.0
mL of 0.33 M NH4Cl. Kb for NH3 = 1.76 x 10-5
A. 4.93
B. 5.25
C. 9.07
D. 9.25
E. 11.3
Ans. C
17. For CdO(s) + SO3(g) => CdSO4(s) ∆H0 = -279.4 kJ/mol and ∆S0 = -118.4 J/(mol K).
What is ∆G0 in kJ/mol at 127 K?
A. –232
B. –303
C. –264
D. –355
E. –460
Ans. C
18. Given that the Ksp value for barium iodate, Ba(IO3)2 is 1.5 x 10-9, calculate its molar
solubility in water at 25 oC?
A. 3.9 x 10-5
B. 1.9 x 10-5
C. 7.2 x 10-4
D. 9.1 x 10-4
E. 1.4 x 10-26
Ans C
19. Which of the following salts will be MORE soluble in an acidic solution than in pure
water?
A. AgCl
B. PbI2
C. CaF2
D. CuBr
E. all will be more soluble in acidic solution
Ans. C
20. Calculate E°cell for 2Cr(s) + 3I2(s) → 2Cr3+(aq) + (aq) + 6I-(aq) and indicate
whether the overall reaction is spontaneous or nonspontaneous.
I2(s) + 2e- => 2I-(aq)
Cr3+(aq) + 3e- => Cr(s)
E° = 0.53 V
E° = -0.74 V
A. E°cell = 0.21 V, spontaneous
B. E°cell = -0.21 V, nonspontaneous
C. E°cell = 1.27 V, spontaneous
D. E°cell = 3.07 V, spontaneous
E. E°cell = -1.27 V, nonspontaneous
Ans. C