Question

Identify the compound of calcium which is used for plastering of fractured bones. With the help of chemical

equation show how is it prepared and what special precautions should be taken during the preparation of this

compound.

Answer 1

i) CaSO4.½H2O i.e. calcium sulphate hemihydrate

ii)CaSO4.½H2O + 1½H2O gives CaSO4.2H2O

Plaster of Paris is a white powder on mixing with water,it changes in gypsum once again giving a hard solid mass.

Answer 2

Answer:

Chemical formula of Plaster of Paris.

CaSO₄. 1/2 H₂O

Preparation :

On heating Gypsum at 373 K Plaster of Paris is formed.

CaSO₄. 2 H₂O    ⇒ CaSO₄. 1/2 H₂O + 3/2 H₂O

Special precaution :

We shouldn't heat gypsum above 373 K else it will not form.