South Pasadena • AP Chemistry
Name
7 ▪ Electrochemistry
Period
7.2
PROBLEMS
1. Use the Table of Standard Reduction Potentials, determine whether the following statements are true or false. a. Magnesium will react with water to produce hydrogen gas.
b. A piece of nickel immersed in a solution of silver nitrate will become coated with silver.
c. In basic solution, manganese(IV) oxide will oxidize mercury to mercury(II) oxide.
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Date
NERNST EQUATION
a. Write the equation for the overall reaction, and calculate the standard cell potential.
b. Calculate the value of the equilibrium constant.
c. For each of the following changes, determine whether the voltage of the cell would increase, decrease, or remain the same. i. [Al3+] = 2.0 M
d. The iodate ion in acidic solution will oxidize copper metal. ii. [Zn2+] = 2.0 M
e. Nitric acid will oxidize tin to Sn2+, producing nitric oxide, NO.
iii. [Al3+] = 0.10 M
iv. [Zn2+] = 0.10 M 2. Consider the electrochemical cell shown below: v. A larger piece of Al° is used.
vi. A larger piece of Zn° is used.
d. Consider the electrochemical cell with [Zn2+] = 2.0 M and [Al3+] = 0.10 M. Calculate the value of Ecell at 25°C with these concentrations.
3. Consider the reaction of copper metal with silver ions in a solution of silver nitrate. a. Write the oxidation and reduction halfreactions, and the balanced overall net ionic equation for this reaction.
4. A galvanic cell is based on the following half reactions at 25°C: Ag+ + e– → Ag H2O2 + 2 H+ + 2e– → 2 H2O a. Write the overall net ionic equation for this reaction. Find the value of E°cell.
b. Find the values of K and ∆G°. b. Calculate the standard cell potential for this reaction. Is this process spontaneous?
c. Calculate the value of the equilibrium constant at 25°C. c. Predict whether Ecell is larger or smaller than E°cell for each of these cases. Then calculate Ecell. i. [Ag+] = 1.0 M, [H2O2] = 2.0 M, [H+] = 2.0 M d. Calculate the value of ∆G° for this reaction.
ii. [Ag+] = 2.0 M, [H2O2] = 1.0 M, [H+] = 1.0 × 10–7 M
AP Chemistry 2006B #2 Answer the following questions about voltaic cells. (a) A voltaic cell is set up using Al/Al3+ as one half-cell and Sn/Sn2+ as the other half-cell. The half-cells contain equal volumes of solutions and are at standard conditions. i. Write the balanced net-ionic equation for the spontaneous cell reaction.
ii. Determine the value, in volts, of the standard potential, E°, for the spontaneous cell reaction.
iii. Calculate the value of the standard free-energy change, ∆G°, for the spontaneous cell reaction. Include units with your answer.
(b) In another voltaic cell with Al/Al3+ and Sn/Sn2+ half cells, [Sn2+] is 0.010 M and [Al3+] is 1.00 M. Calculate the value, in volts, of the cell potential, Ecell, at 25°C.
