PDF chapter test TRY NOW
The calcium sulphate hemihydrate is commonly known as plaster of Paris. The name is derived from the place of its origin Montmartre in the Paris district. The chemical formula is .
Preparation of plaster of Paris:
When gypsum is heated in a rotating kiln at \(373 K\), it loses all its water molecule and forms calcium sulphate hydrate\((CaSO_4)_2.H_2O\).
\(2CaSO_4.2H_2O \xrightarrow {373K}(CaSO_4)_2.H_2O + 3H_2O\)
Properties of plaster of Paris:
- It is a white colour powder.
- It acts as an oxidizing agent under extreme conditions.
- It produces gypsum when mixed with water.
\(CaSO_4.\frac{1}{2}H_{2}O + 1\frac{1}{2}.H_{2}O\rightarrow CaSO_4.2H_2O\)
Plaster of Paris uses:
 |
Uses of Plaster of Paris
- It is used in construction for making walls smooth and to create designs on walls and ceilings.
- It is used in making chalks and also helps in setting fractured bones during surgery.
- In laboratories, it is used to seal the air gaps in the apparatus.
- It is used in making caste for the statue, dentistry, surgical instruments, toys, etc.
Register for free to see more content