Question

The reaction which is taking place in nickel - cadmium battery can be represented by which of the following equation?

• A. $Cd+NiO_{2}+2H_{2}O \to Cd\left(OH\right)_{2}+Ni\left(OH\right)_{2}$
• B. $Cd+NiO_{2}+2OH^{-} \to Ni+Cd\left(OH\right)_{2}$
• C. $Ni+Cd\left(OH\right)_{2} \to Cd+Ni\left(OH\right)_{2}$
• D. $Ni\left(OH\right)_{2} + Cd\left(OH\right)_{2} \to Ni + Cd + 2H_{2}O$

Answer 1

Answer: (A)

Nickel-Cadmium battery
Anode - $Cd$ ; Cathode - $NiO_2$; Electrolyte - $KOH$
At anode : $Cd_{\left(s\right)}+2OH^{-}_{\left(aq\right)} \to Cd\left(OH\right)_{2\left(s\right)}+2e^{-}$
At cathode : $NiO_{2\left(s\right)}+2H_{2}O_{\left(l\right)}+2e^{-} \to Ni\left(OH\right)_{2\left(s\right)}+2OH^{-}_{\left(aq\right)}$
$Cd_{\left(s\right)}+NiO_{2\left(s\right)}+2H_{2}O_{\left(l\right)} \to Cd\left(OH\right)_{2\left(s\right)}+Ni\left(OH\right)_{2\left(s\right)}$