Write the balanced equation for the redox reaction corresponding to the charging process.

Question

The half-reactions and their associated standard reduction potentials in nickel-cadmium batteries are

NiO(OH)(s) + H₂O (l)+ e^- Ni(OH)₂ ​(s)+ OH^- (aq) E° = 1.32 V

Cd (OH)₂ + 2e^- Cd (s) + 2OH^- (aq) E° = -0.40 V

Answer 1

NiO(OH)(s) + H₂O (l) + e^- Ni(OH)₂ ​(s)+ OH^- (aq) ... reduction half reaction (cathode)

Cd (s) + 2OH^- (aq) Cd (OH)₂ + 2e^- ... oxidation half reaction (anode)

Multiply reduction half reaction by 2 in order to equalize electrons, then add the 2 reactions together:

2NiO(OH)(s) + 2H₂O (l)+ 2e^- 2Ni(OH)₂ ​(s)+ 2OH^-(aq)

Cd (s) + 2OH^- (aq) Cd (OH)₂ + 2e^-

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2NiO(OH)(s) + Cd(s) + 2H₂O(l) 2Ni(OH)₂ ​(s) + Cd (OH)₂ ... BALANCED REDOX

If you want to Eº_cell, it is simply 1.32 V + 0.40 V = 1.72V