Sodium (Down’s
Process)
Introduction
On large scale, sodium is
manufactured by electrolysis of fused sodium chloride. The process was given by
scientist Dawn, therefore, it is called Dawn’s Process.
Construction of Down’s Cell
A special electrolytic cell known as
Dawn’s cell is used for the electrolysis of sodium carbonate. The cell consists
of a cylindrical shape iron basin lined inside by firebricks. The iron cathode
is separated from anode by iron gauze diaphragm. Anode consists of a carbon
rod, which is present between two iron cathodes. The electrolytic solution
consists of a mixture of sodium chloride (NaCl) and calsium chloride (CaCl2).
Calsium Chloride (CaCl2) is added to decrease the melting point of sodium
chloride from 801ºC to 600ºC.
Working of Dawn’s Cell
When electric current is passed
through molten NaCl, the sodium ion migrates towards cathode. It gains and
electron and converts into molten sodium metal, which floats inside the cathode
compartment. This molten sodium metal is allowed to pass through pipe ‘p’ which
collects it in a vessel ‘V’ outside the cell.
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