Question

What is water of crystallization? How is plaster of paris prepared? Write any two used of plaster of paris​

Answer 1

Answer:

• Water of crystallization is the fixed number of water molecules present in one formula unit of a salt.  

For example, Copper sulphate has 5 molecules of water of crystallisation.

• The name plaster of Paris came from the fact that it was first of all made by heating gypsum which was mainly found in Paris. The compound plaster of Paris is prepared by heating gypsum at 120oC.

CaSO4.2H2O → CaSO4.1/2H2O + 3/2H2O

The chemical formula for the plaster of Paris is (CaSO4) H2O and is better known as calcium sulfate hemihydrate.

• Used in making casts and patterns for molds and statues.

• Used as the cement in ornamental casting and for making decorative materials