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Batteries

Exercise 2

          

Given the nickel cadmium accumulator in a basic medium: NiO(OH) / Ni(OH)2 and Cd(OH)2/Cd The cadmium is oxidised. Write the equations of the reactions at the electrodes!

A natural reaction takes place between the strongest reducing agent Cd and the strongest oxidising agent NiO(OH): NiO(OH)+ H2O+e- Ni(OH)2+OH- Cd+2OH- Cd(OH)2+2e- During the charge the opposite reactions take place.

Which is the negative battery terminal ?

The cadmium metal is the strongest reductant, so the negative terminal is the cadmium electrode.