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Question
Starting with sodium chloride how would you proceed to prepare sodium hydroxide.
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Solution
Sodium hydroxide can be prepared by the electrolysis of sodium chloride. This is called Castner–Kellner process. In this process, the brine solution is electrolysed using a carbon anode and a mercury cathode.
The sodium metal, which is discharged at a cathode, combines with mercury to form an amalgam.
\[\ce{Cathode: Na+ + e- ->[Hg] Na - amalgam}\]
Anode: \[\ce{Cl -> 1/2 Cl_2 + e-}\]
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