Question
The reaction which is taking place in nickel - cadmium battery can be represented by which of the following equation?
A.
$$Cd + Ni{O_2} + 2{H_2}O \to $$ $$Cd{\left( {OH} \right)_2} + Ni{\left( {OH} \right)_2}$$
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.
$$Ni{\left( {OH} \right)_2} + Cd{\left( {OH} \right)_2} \to $$ $$Ni + Cd + 2{H_2}O$$
Answer :
$$Cd + Ni{O_2} + 2{H_2}O \to $$ $$Cd{\left( {OH} \right)_2} + Ni{\left( {OH} \right)_2}$$
Solution :
Nickel-Cadmium battery
Anode - $$Cd;$$ Cathode - $$Ni{O_2};$$ Electrolyte - $$KOH$$
$$\eqalign{
& {\text{At anode :}}\,C{d_{\left( s \right)}} + 2OH_{\left( {aq} \right)}^ - \to Cd{\left( {OH} \right)_{2\left( s \right)}} + 2{e^ - } \cr
& \underline {{\text{At cathode}}:\,Ni{O_{2\left( s \right)}} + 2{H_2}{O_{\left( l \right)}} + 2{e^ - } \to Ni{{\left( {OH} \right)}_{2\left( s \right)}} + 2OH_{\left( {aq} \right)}^ - } \cr
& \underline {C{d_{\left( s \right)}} + Ni{O_{2\left( s \right)}} + 2{H_2}{O_{\left( l \right)}} \to Cd{{\left( {OH} \right)}_{2\left( s \right)}} + Ni{{\left( {OH} \right)}_{2\left( s \right)}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \cr} $$