Page 2 - 3.LESSON NOTES-(CH-2 WASHING SODA& PLASTER OF PARIS)

Washing Soda

• It is soluble in water.
• The solution of washing soda in water is alkaline which turns red litmus to blue.
• Strong Base
• It has cleansing properties due to its Alkaline nature.
• When Washing soda is heated strongly, it loses its water of crystallization to
form dehydrated Sodium carbonate (Soda Ash).

Na2CO3 . 10H2O --heat-→ Na2CO3 + 10H2O
Washing Soda Soda Ash

• When Washing soda is left exposed to air, it loses nine of its water of
crystallization to form Sodium carbonate mono hydrate.

This processes of losing Water of crystallization to the atmosphere when left
exposed to air, is known as Efflorescence.

Na2CO3 . 10H2O --exposed to atm--→ Na2CO3 . H2O + 9H2O
Washing Soda sodium carbonate
mono hydrate
 Uses of Washing Soda:
• Sodium carbonate (washing soda) is used in glass, soap, and paper industries.

• It is used in the manufacture of sodium compounds such as Borax.
• It is used to remove Hardness of water OR Make Hard Water soft.

Difference in appearance of Hard & soft water

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