Answer:
Cd is oxidized during the discharge of the battery
Explanation:
Based on the reaction:
2 NiOOH + Cd + 2H₂O → 2Ni(OH)₂ + Cd(OH)₂
And knowing Oxygen and hydrogen never change its charge, we must to find oxidation state of Ni and Cd before and after the reaction:
Ni:
In NiOOH: 2 O = -2*2 = -4 + 1H = +1, = -4 + 1 = -3. And as the molecule is neutral, Ni is 3+
In Ni(OH)₂: OH = -1. As there are 2 OH = -2. That means Ni is +2
The Ni is gaining one electron, that means is been reduced
Cd:
Cd before reaction is as pure solid with oxidation state = 0
Cd after the reaction is as Cd(OH)₂: 2 OH = -2. That means Cd is +2
The Cd is loosing 2 electrons, that means is the species that is oxidized.
