Electrochemistry Test

Chemistry 3202 Electrochemistry Test

Name: ______January 17, 2014

Instructions: Place the letter of the correct answer in the spaces provided on this sheet.

1. How does an Fe atom change into an Fe2+ ion? A. Oxidizes and gains 2 electrons 1. _____ B. Oxidizes and loses 2 electrons C. Reduces and gains 2 protons D. Reduces and loses 2 protons

2. What is the oxidation number of magnesium in MgSO4? A. -2 B. -1 2. _____ C. +1 D. +2

3. What is the oxidation half reaction for 2K(s) + F2(g)  2KF(s)? 3. _____ A. K+(aq) + e-  K (s) B. K(s)  K+(aq) + e- C. - - F2(g) + 2e  2F (aq) D. - - 2F (aq)  F2(g) + 2e

4. Which equation represents a redox equation? 4. _____ A. + 2- Ag2CrO4  2 Ag + CrO4 B. AgNO3 + NaCl  AgCl + NaNO3 C. 2 H2 + O2  2 H2O D. + - H3O + OH  2 H2O

5. What is the function of a salt bridge in a galvanic cell? A. provides a path for electrons 5. _____ B. a way of automatically replenishing the cell electrolyte C. a means of connecting two half cells while preventing mixing of the two solutions D. a method used to increase the resistance to current flow in the circuit

o 6. Given the redox reaction below, what is the Ecell for the reaction? 6. _____

Sn4+(aq) + Co(s)  Co2+(aq) + Sn2+(aq)

A. -0.43V B. -0.13V C. +0.13V D. +0.43V

7. If 0.160 mol of a metal produces 46300 coulombs of charge, how many electrons does the metal gain in its half reaction? A. 1 B. 2 7. _____ C. 3 D. 4

8. Which cell uses electrical energy to cause a non-spontaneous redox reaction? 8. _____ A. Electrochemical B. Electrolytic C. Galvanic D. voltaic

9. At which electrode does reduction occur in an electrolytic cell? 9. _____ A. anode B. cathode C. salt bridge D. voltmeter 10. Consider an electrochemical cell where the following reaction takes place:

2 Au3+(aq) + 3 Zn(s) → 2 Au(s) + 3 Zn2+(aq)

Which of the following is the correct cell notation for this cell? A. Au | Au3+ || Zn2+ | Zn 10. _____ B. Au3+ | Au || Zn | Zn2+ C. Zn | Zn2+|| Au3+ | Au D. Zn | Au3+ || Au | Zn2+

11. For the electrochemical cell below the E°cell is 0.94V. 11. _____ X(s)|X2+(aq, 1M) || Ag+(aq, 1M) | Ag(s)

What is the E° value for X2+(aq) + 2e-  X(s)? A. -0.66 V B. -0.14 V C. 0.14 V D. 0.66 V

12. Which 1.0mol/L salt solution would combine with Mg(s) to give a voltaic cell with the highest voltage? A. Al3+ (aq) 12. _____ B. Cu2+ (aq) C. Fe2+ (aq) D. Zn2+ (aq)

13. Find the quantity of electricity that results from a current of 3.50A flowing for 6.00min. A. 0.35 C B. 0.58 C 13. _____ C. 21.0 C D. 1.26 x 103 C

14. What happens to the mass of the chromium electrode in the diagram below? 14. _____

A. decreases as it oxidizes B. decreases as it is reduced C. increases as it is oxidized D. increases as it is reduced

15. Which is a primary cell? 15. _____ A. Button B. Hydrogen fuel C. Lead-storage D. Rechargeable Constructed Response: Answer each question in the space provided.

16. Balance the following redox reactions: A. 2- 3+ H2S + Cr2O7  Cr + S Acidic Solution

- - - B. MnO4 + CN  MnO2 + OCN Basic Solution

17. Are the following redox reactions spontaneous as written? Explain. A. Ni(s) + Zn2+(aq)  Ni2+(aq) + Zn(s)

B. 3Cu2+(aq) + 2Al(s)  3Cu(s) + 2Al3+(aq) 18. Draw a voltaic cell for the following standard cell: Fe (s) | Fe2+ (aq) || Ag+ (aq) | Ag (s) Indicate: 1. Anode 2. Cathode 3. Direction of electron flow 4. Salt Bridge 5. Direction of ion flow 6. Substance Oxidized 7. Substance Reduced 8. Oxidizing Agent 9. Reducing Agent

19. Aluminum can be produced by the electrolysis of molten aluminum chloride, AlCl3. If a 5.00A current is passed through for 1.50h, what mass of aluminum will be produced?