Chlorine (Castner-Kellner's)
2nd Year Chemistry Notes
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Chlorine (Castner-Kellner's)
Introduction
Chlorine plays an important role in industries. Therefore to fulfill
the demands, chlorine is manufactured on large scale. It is prepared by
the electrolysis of aqueous solution sodium chloride, this process is
known as Castner-Kellner's Process and it is carried out in
Castner-Kellner's Cell.
Construction of Castner-Kellner's Cell
The Castner-Kellner's cell consist of a steel tank which contain Hg
flows from right to left in the cell and is connected with the negative
terminal of the battery therefore it acts as cathode. The cell is
filled with saturated aqueous solution of NaCl, which also flows in the
same direction as Hg. Some graphite rods are dipped into the solution
of NaCl. These rods connected with positive terminal of the battery
therefore act as anode.
Working Of Castner-Kellner's Cell
When the electric current is passed through the cell. The sodium ion
and chloride ion migrates towards their respective electrodes. Chlorine
ion moves towards anode, loses its electron and converts into chlorine
gas. The free chlorine gas comes out of the tube at the top of the
cell. The sodium ion migrates towards cathode gains electrons and
converts into sodium metal. The sodium is dissolved in Hg to form
sodium amalgum which comes out with the flow of Hg from the cell.
NaCl <----> Na+ + Cl-
Na+ + e- ----> Na0 (At Cathode)
2Cl ----> Cl2↑ + 2e (At anode)
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2nd Year Chemistry Notes