Question

Given the reaction for the nickel-cadmium battery: 2NiOOH + Cd +2H2O -> 2Ni(OH)2 + Cd(OH)2 What species is oxidized during the discharge of the battery?

Answer 1

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.