The redox equilibria for a rechargeable nickel–cadmium cell during discharge are based on the standard electrode potentials below:
Cd(OH)2(s)+2e−⇌Cd(s)+2OH−(aq)Eθ=−0.80 V \text{Cd(OH)}_2(\text{s}) + 2\text{e}^- \rightleftharpoons \text{Cd}(\text{s}) + 2\text{OH}^-(\text{aq}) \quad E^\theta = -0.80\text{ V} Cd(OH)2(s)+2e−⇌Cd(s)+2OH−(aq)Eθ=−0.80 V NiO(OH)(s)+H2O(l)+e−⇌Ni(OH)2(s)+OH−(aq)Eθ=+0.49 V \text{NiO(OH)}(\text{s}) + \text{H}_2\text{O}(\text{l}) + \text{e}^- \rightleftharpoons \text{Ni(OH)}_2(\text{s}) + \text{OH}^-(\text{aq}) \quad E^\theta = +0.49\text{ V} NiO(OH)(s)+H2O(l)+e−⇌Ni(OH)2(s)+OH−(aq)Eθ=+0.49 VWhat is the overall equation for the cell reaction during discharge?
24 exam-style questions on OCR A A Level Chemistry Redox and electrode potentials. Each one has a worked solution and a mark scheme showing where the marks go.