1. Review- Electrochemistry

2. How it works Partner “green” will discuss a strategy on how to complete the problem Then, Partner “blue” will comment on the strategy and add any further details needed and write down the steps to solving the problem, without actually solving it. Finally, Partner “red” will use the strategy that the other two partners outlined to actually complete the problem. Roles will be rotated each problem

3. Problem 1 (Blue, green, red) How many grams of aluminum can be deposited if 31,500 coulombs of electricity pass through an aluminum nitrate solution?

4. answer 2.94 grams

5. Problem 2: (green, red, blue) Balance the following equation AsH 3 + ClO 3 -  H 3 AsO 4 + Cl- (acidic soln)

6. answer 3 AsH3 + 4ClO3-  4Cl- + 3H3AsO4

7. Problem 3 (red, blue, green) If 10.0 amperes of current flow for 20.0 minutes through a solution of copper (II) nitrate, how many moles of copper are deposited?

8. answer 0.062 moles

9. Problem 4: (red,blue,green) Water was electrolyzed for 5.61 minutes using a constant current of 0.513 amperes. Calculate the volume, in liters, of hydrogen gas produced at 298 K and 1.00 atm.

10. answer 0.022 L

11. Problem 5 Calculate E cell for the reaction that occurs when a standard voltaic cell of Zn/Zn 2+ and Al /Al 3+ have concentrations of 0.100 M and 0.0500M respectively.

12. answer 0.896 V

13. Problem 6: (red, green, blue) 5.77 g of zinc is deposited at the cathode when a current of 7.1 amperes passes through an electrolytic cell for 40. minutes. What is the oxidation state of the zinc in the aqueous solution?

14. answer Zn 2+ Should find that there are 0.088 moles of Zn and 0.17658 moles of electrons- which must mean that there need to be 2 moles of electrons per mole of Zn meaning that the oxidation state is 2.

15. Problem 7: Balance the following reaction: N 2 O 4 + Br -  NO 2 - + BrO 3 -(basic soln)

16. answer Br- + 6OH- + 3 N 2 O 4  6 NO 2 - + BrO 3 - + 3H 2 O

17. Problem 8: (green, red, blue) Choose the best reducing and oxidizing agent from the following: – Cu(s) – Zn(s) – Ag + – Al 3+ – F- – F 2

18. answer Strongest oxidizing agent: F2 (it itself is reduced) Strongest reducing agent: Zn (it itself is oxidized)

19. Problem 9: (red, blue, green) All of the following substances can act as oxidizing agents except: a.H 2 O 2 b.Cr 2 O 7 2- c.MnO 4 – d.IO 3 – e.Br –

20. answer Br-

21. Problem 10: (blue, red, green) Calculate K(the equilibrium constant) at 298K for the following reaction: Cl 2 (g) + 2I - (aq)  2 Cl - (aq) + I 2 (s)

22. answer E⁰=0.83V K=1.2x10 28 or 1.1x10 28