Sodium hydroxide: Manufacture, properties and uses

Sodium hydroxide is commonly called caustic soda because of its corrosive action on animal and vegetable tissues. Large quantity of sodium hydroxide is prepared by electrolytic process called the 'Chlor-alkali process'. Here, chlorine gas is given of at the anode and hydrogen gas at the cathode. Sodium hydroxide solution is formed near the cathode.


  • Sodium hydroxide is a white deliquescent solid having melting point at 591 K (318°C)
  • It is stable towards heat
  • It is highly soluble in water and considerable amount of heat is evolved due to the formation of a number of hydrates e.g., NaOH.H2O, NaOH.2H2O. It is also soluble in alcohol
  • Aqueous solution of sodium hydroxide is strongly alkaline due to its complete dissociation into Na+ and OH-
property of sodium hydroxide or caustic soda

  • Solution of sodium hydroxide is soapy to touch. It has a bitter taste. When a concentrated solution of sodium hydroxide comes in contact with skin, it breaks down the skin and flesh to a pasty mass.


  • In the manufacture of soap, paper, viscose rayon (artificial silk), organic dyestuffs, and many other chemicals
  • In the refining of petroleum and vegetable oils
  • In the purification of bauxite for the extraction of aluminium
  • As a cleansing agent and in washing powder for machines, metal sheets etc. It is too caustic to be used in washing clothes or hands
  • For mercerizing cotton
  • As a reagent in the laboratory
  • In reclaiming rubber
  • In the preparation of soda lime

No comments: