AP Chemistry - Electrochemistry

1. Balance the following redox reactions using any method you choose.

a) ClO3- + NO ---> NO3- + HClO2 (in acidic solution)

b) CrO4-2 + Si ---> SiO3-2 + Cr+3 (Basic solution)

c) AgCl + Sn + S-2 ---> SnS + Ag + Cl-1

2. Draw the galvanic cell that can be produced from acidic solutions of ferric and ferrous ions, and cupric and cuprous ions. Calculate the voltage of the cell at standard conditions and label all of the following.



salt bridge (be sure to label what should be in the salt bridge)

the direction the electrons flow

where oxidation takes place

where reduction takes place

which direction the positive ions of the salt bridge will flow

what the electrodes are made of

what is in each of the solutions

3. Calculate the standard voltage on the cell created using MnO4-1 and Sn+2 ions in acidic solution.

What will the voltage of this cell be if all of the concentrations are 0.45 M?

(By the way, R = 8.314 J/mol·K, F = 96,485 J/volt mol, and assume that T= 298 K)

4. What are all of the possible reactions when an aqueous solution of sodium bromide is electrolyzed?

Which two will actually occur and what voltage will be required to run this electrolysis?

5. How many grams of Pb can be plated out by electrolyzing a solution of Pb+2 with

2.3 amps for 7.00 hours? (The Faraday = 96,485 Coulombs/mol of electrons,

1 coulomb = 1 amp*sec)

6. Label the oxidation numbers of each element in the following compounds.

(NH4)2Cr2O7 LiNO2 Mg(CN)2

7. In galvanized steel, the steel is coated with a thin layer of zinc. This zinc is often called a sacrificial anode. How does this protection work and what property of the metals is involved?