Question

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

• A. $Cd+Ni{O}_2+2H_{2}O\to Cd{\left(OH\right)}_2+Ni{\left(OH\right)}_2$
• B. $Cd+Ni{O}_2+2O{H}^{-}\to Ni+Cd{\left(OH\right)}_2$
• 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 - $Ni{O}_2$; Electrolyte - $KOH$
At anode : $C{d}_{\left(s\right)}+2O{H}_{\left(aq\right)}^{-}\to Cd{\left(OH\right)}_{2\left(s\right)}+2e^{-}$
At cathode : $Ni{O}_{2\left(s\right)}+2H_2{O}_{\left(l\right)}+2e^{-}\to Ni{\left(OH\right)}_{2\left(s\right)}+2O{H}_{\left(aq\right)}^{-}$
$C{d}_{\left(s\right)}+Ni{O}_{2\left(s\right)}+2H_2{O}_{\left(l\right)}\to Cd{\left(OH\right)}_{2\left(s\right)}+Ni{\left(OH\right)}_{2\left(s\right)}$