Sodium Hydroxide (NaOH)
Sodium Hydroxide (NaOH)
Sodium hydroxide or Caustic Soda is generally prepared
commercially by the electrolysis of sodium chloride in Castner-Kellner cell. A
brine solution is electrolysed using a mercury cathode and a carbon anode.
Sodium metal discharged at the cathode combines with mercury to form sodium
amalgam. Chlorine gas is evolved at the anode.
The amalgam is treated with water to give sodium hydroxide
and hydrogen gas.
2Na-amalgam + 2H2O → 2NaOH + 2Hg
+ H2
Sodium hydroxide is a white, translucent solid. It melts at
591 K. It is readily soluble in water to give a strong alkaline solution. Crystals
of sodium hydroxide are deliquescent. The sodium hydroxide solution at the
surface reacts with the CO2 in the stmosphere to form Na2CO3.
Uses
It is used in
- The manufacture of soap, paper, artificial silk and number of chemicals.
- In petroleum refining
- In the purification of bauxite.
- In the textile industries for mercerizing cotton fabrics,
- For the preparation of pure fats and oils
- As a laboratory reagent.
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