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.