CHM 2046 Test #4 Review: Chapter 17 & Chapter 18

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1 1. Which of the following is true concerning a nonspontaneous reaction? a. It s impossible for the reaction to occur b. The reaction occurs, but very slowly c. It can be made spontaneous by adding a catalyst d. The reaction occurs without ongoing outside intervention e. It can be made spontaneous by coupling it to a spontaneous reaction 2. Which of the following processes are spontaneous? a. A bike going up a hill b. Obtaining hydrogen gas from liquid water c. The combustion of natural gas d. The extraction of iron metal from iron ore e. None of the above 3. Which of the following would have a positive change in entropy? a. Na (s) + ½ Cl 2 NaCl (s) b. 2 O 3 3 c. N H 2 2 NH 3 d. N NO e. 2 N N 2 O 4. At 25, a reaction has a ΔH rxn = +125 kj and ΔS rxn = +253 J/K.What is the value for the change in Gibb s free energy and is the reaction spontaneous or nonspontaneous? a. 6,200 kj; spontaneous b. 75,269 kj; spontaneous c kj; spontaneous d kj; nonspontaneous e kj; nonspontaneous 5. A reaction has ΔH rxn = 127 kj and ΔS rxn = 314 J/K. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings? a. 404 K b. 298 K c K d K e K 6. Rank each of the following in order of increasing standard molar entropy. { H 2 O ; H 2 ; H 2 S }

2 a. H 2 O ; H 2 ; H 2 S b. H 2 O ; H 2 S ; H 2 c. H 2 ; H 2 S ; H 2 O d. H 2 S ; H 2 O ; H 2 e. H 2 S ; H 2 ; H 2 O 7. What is ΔG rxn for the following reaction: Fe 2 O 3 (s) + 3 CO 2 Fe (s) + 3 C Use the following reactions and given ΔG rxn values: 2 Fe (s) + 3/2 Fe 2 O 3 (s) ΔG rxn = kj CO + ½ O2 C ΔG rxn = kj a kj b kj c kj d. 9.8 kj e kj ***Use the following reaction and table with standard entropy & free energy of formation values in order to answer questions #8, #9, and #10. 2 CO + 2 C Substance S (J/mol*K) ΔG f (kj/mol) CO C CO 2 (aq) O O

3 8. What is the value ΔS rxn? a J b. 173 J c J d J e J 9. What is the value of ΔG rxn? a b c kj d kj e kj 10. What is the change in free energy at 25 under the following conditions. P CO = atm P O2 = atm P CO2 = atm a kj b kj c kj d kj e kj 11. What is the coefficient of H+ when the following reduction oxidation reaction is balanced in an acidic solution? SO 3 2 (aq) + MnO 4 (aq) SO 4 2 (aq) + Mn 2+ (aq) a. 2 b. 4 c. 6 d. 7 e What is the coefficient of H 2 O when the following reduction oxidation reaction is balanced in a basic solution?

4 BrO 3 (aq) + N 2 H 4 Br (aq) + N 2 a. 2 b. 4 c. 6 d. 7 e. 11 ***Use the voltaic cell below to answer questions #13 and #14. ***Use the table of standard reduction potentials to answer questions #13, #14, 15, #16, #17, #19, and #20. ½ Reaction Standard Reduction Potential (V) Fe 3+ (aq) + e Fe 2+ (aq) Fe 2+ (aq) + 2e Fe (s) 0.45 Fe 3+ (aq) + 3e Fe (s) Cr 3+ (aq) + e Cr 2+ (aq) 0.50 Cr 3+ (aq) + 3e Cr (s) 0.73

5 Sn 4+ (aq) + 2e Sn 2+ (aq) Sn 2+ (aq) + 2e Sn (s) 0.14 Cd 2+ (aq) + 2e Cd (s) 0.40 Ni 2+ (aq) + 2e Ni (s) Which of the following is true about the voltaic cell? a. Cr 3+ (aq) is reduced to Cr (s) b. Cations in the salt bridge move toward the Cd 2+ (aq) solution c. Fe is the positive electrode d. In the wire, electrons flow from Iron to Chromium e. All of the above 14. What is the electrochemical cell notation of the voltaic cell? a. Fe (s) Fe 3+ (aq) Cr 3+ (aq) Cr (s) b. Cr (s) Cr 3+ (aq) Fe 3+ (aq) Fe (s) c. Fe (s) Fe 3+ (aq), Cr 3+ (aq) Cr (s) d. Cr (s) Cr 3+ (aq) Fe 3+ (aq) Fe (s) e. Fe 3+ (aq) Fe (s) Cr (s) Cr 3+ (aq) 15. Which of the following is a spontaneous reduction oxidation reaction? a. 2 Fe 3+ (aq) + Fe (s) 3 Fe 2+ (aq) b. 3 Fe 2+ (aq) 2 Fe 3+ (aq) + Fe (s) c. 3 Fe 2+ (aq) Fe (s) + 2 Fe 3+ (aq) d. 2 Sn 2+ (aq) Sn 4+ (aq) + Sn (s) e. 3 Cr 2+ (aq) Cr (s) + 2 Cr 3+ (aq) 16. What is the ΔG rxn for the reaction below? 2 Fe 3+ (aq) + 3 Sn (s) 2 Fe (s) + 3 Sn 2+ (aq) a kj b J c kj d J e kj 17. A concentration cell consists of two Sn/Sn 2+ half cells. The cell has a potential of 0.10 V at 25. What is the ratio of the Sn 2+ concentrations in the two half cells?

a. 3.2 x 10 3 b. 3.2 x 10 4 c. 2.4 x 10 4 d. 4.2 x 10 4 e. 4.8 x 10 6 18. Which of the following is an example of a dry cell battery? a. Car battery b. Cell phone battery c. AA battery d.

6 a. 3.2 x 10 3 b. 3.2 x 10 4 c. 2.4 x 10 4 d. 4.2 x 10 4 e. 4.8 x Which of the following is an example of a dry cell battery? a. Car battery b. Cell phone battery c. AA battery d. Rechargeable battery e. Fuel cell ***Use the electrolytic cell below to answer questions #19 and # Which of the following is true about the electrolytic cell? a. Nickel is the positive electrode b. Cd is oxidized to Cd 2+ c. In the wire, electrons flow from Cadmium to Nickel d. Anions in the salt bridge move toward the Cd 2+ (aq) solution e. None of the above 20. What is the minimum voltage necessary to drive the reaction?

7 a. 0 V b V c V d V e V 1. E 2. C 3. B 4. D 5. A 6. A 7. E 8. B 9. D 10. D 11. C 12. C 13. C 14. B 15. A 16. D 17. D 18. C 19. A 20. E

CHM 2046 Final Exam Review: Chapters 11 18

CHM 2046 Final Exam Review: Chapters 11 18 Chapter 11 1. Which of the following has the lowest boiling point? a. NH 3 b. CH 3 Cl c. NaCl d. CO 2 e. CH 3 CH 2 CH 2 CH 2 CH 3 2. Which of the following has the lowest vapor pressure? a. CH 3 F b. CH