Practice: Calculate the standard cell potential of an electrolytic cell when given the following half reactions.
Standard Reduction Potentials
Fe3+ (aq) + e – → Fe2+ (aq) E°red = + 0.769 V
Li+ (aq) + e – → Li (s) E°red = – 3.04 V
Concept #1: The calculated standard cell potential is measured in units of volts (V).
Example #1: What is E°cell for a voltaic cell based on the following reduction reactions in which the copper electrode is the cathode and the zinc electrode is the anode?
Zn2+ (aq) + 2 e– → Zn (s) E°red = - 0.7621
Cu2+ (aq) + 2 e– → Cu (s) E°red = + 0.3394
Concept #2: A galvanic cell possesses a standard cell potential that is greater than zero.
Example #2: Given the following redox reaction: Ce (s) + Al3+ (aq) → Al (s) + Ce3+ (aq). Find its standard cell potential when given the following half-reactions.
Standard Reduction Potentials
Ce3+ + 3 e- → Ce (s) E°red = – 2.336
Al3+ + 3 e- → Al (s) E°red = – 1.677
Practice: Calculate the standard cell potential of an electrolytic cell when given the following half reactions.
Standard Reduction Potentials
Fe3+ (aq) + e – → Fe2+ (aq) E°red = + 0.769 V
Li+ (aq) + e – → Li (s) E°red = – 3.04 V
Practice: Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.
3 Cl2 (g) + 2 Fe (s) → 6 Cl – (aq) + 2 Fe3+ (aq)
Standard Reduction Potentials
Cl2 (g) + 2 e– → 2 Cl – (aq) E°red = + 1.396 V
Fe3+ (aq) + 3 e– → Fe (s) E°red = – 0.040 V
Practice: Predict whether the following reaction will occur as written based on the calculated Eºcell.
Ag+ (aq) + Au (s) → Ag (s) + Au3+ (aq)
Standard Reduction Potentials
Ag+(aq) + e– → Ag (s) E°red = + 0.80 V
Au3+ (aq) + 3 e– → Au (s) E°red = + 1.50 V
