Question

Write the formation with reaction and uses of Washing soda , Plaster of Paris.

Answer 1

Washing Soda:

Washing soda is synthesized through Solvay’s process. Solvay’s process involves the reaction of sodium chloride, ammonia and carbon dioxide in water. Carbon dioxide involved is produced through calcium carbonate and the calcium oxide left is used in recovering ammonia from ammonium chloride.

At first, sodium bicarbonate is obtained which is then converted to sodium carbonate on heating. Finally, washing soda is produced by recrystallization of sodium carbonate.

• NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
• 2 NaHCO₃ → Na₂CO₃ + H₂O + CO₂
• Na₂CO₃ + 10H₂O → Na₂CO₃.10H₂O

Uses of Washing Soda:

• Washing soda is used for removing burnt-on grease from kitchen utensils.
• It is prominently used in soap, glass and paper industries.
• It also helps in the removal of permanent hardness of the water.
• It acts as a raw material in the manufacturing of various sodium compounds, for example, borax.

Plaster of Paris:

Plaster of Paris is a chemical compound consisting of fine white powder, which hardens when exposed to moisture and allowed to dry. Its chemical formula of Plaster of Paris is CaSO₄.1/2H₂O and is better known as calcium sulfate hemihydrate.

Plaster of Paris is synthesized from gypsum (CaSO₄.2H₂O). When gypsum is heated at 373 K, it loses its water molecules to become calcium sulphate (plaster of Paris).

CaSO₄.2H₂O → CaSO₄.1/2H₂O + 3/2H₂O

Uses of Plaster of Paris:

• Plaster of Paris is used by doctors for supporting fractured bones in the right position.
• It is used for making toys and decorative materials.
• It is also used for increasing smoothness of surfaces.