Concept #1: The Nernst Equation reveals the quantitative connection between the concentrations of compounds and cell potential.
Example #1: Determine the cell potentials of the following concentration cells:
Ag | Ag+ (aq, 0.0010 M) || Cu2+ (aq, 1.0 M) | Cu
EAnode = 0.799 V ECathode = 0.339 V
Example #2: Consider the following electrochemical cell for the question:
Pt | KBr(aq, 0.01 M), Br2(l) || FeBr2(aq, 1.0M) | Fe
EAnode = 1.078 V ECathode = - 0.440 V
Determine the spontaneity and cell potential based on the given cell notation.
Example #3: Consider a standard voltaic cell based on the reaction:
2 H+ (aq) + Sn (s) ⇌ Sn2+ (aq) + H2 (g)
Which of the following actions would change the emf of the cell?
a) Increasing the pH at the cathode
b) Lowering the pH at the cathode
c) Increasing [Sn2+] at the anode
d) Increasing the hydrogen gas pressure at the cathode
e) All of the above changes will alter the cell potential
Example #4: Consider the following half cell reaction at T = 25. °C
Ni2+(aq) + 2 e – → Ni(s) E° = – 0.260 V
What will be the value for E°, the half cell potential for standard conditions, for the reaction
2 Ni(s) → 2 Ni2+ (aq) + 4 e –
a) + 0.52 V b) + 0.26 V c) – 0.26 V d) – 0.52 V