Question

In Castner-Kellner cell, used for the manufacture of NaOH, the cathode in the central compartment is made of

• A. graphite
• B. mercury
• C. iron
• D. platinum

Answer 1

Answer: (C)

In central compartment, iron is used as cathode and the layer of Hg acts as anode by induction.
In the outer compartments, graphite rods are used as anode and the mercury layer acts as cathode by induction.
Cathode ${\text{Na}}^{\text{+}}\text{+}{\text{e}}^{-}\stackrel{\text{Hg}}{\to }\text{Na-Hg }$ (sodium amalgam)
Anode $2C{l}^{-}\to C{l}_2(g)+2e^{-}$