How is plaster of Paris chemically different from Gypsum ? How can they be inter -converted ? Write two uses of plaster of paris.

Explanation

Plaster of paris chemically is `CaSO_(4) ½H_(2)O`
Gypsum is `CaSO_(4).2H_(2)O`
On heating gypsum at 373 K, it loses water molecule and becomes calcium sulphate hemihydrate. `CaSO_(4) ½H_(2)O`.
Again on treating with water plaster of paris becomes gypsum. `underset("Plaster of paris")(CaSO_(4). ½H_(2)O) + 1 ½ H_(2)O rarr underset("Gypsum")(CaSO_(4).2H_(2)O)`
`underset("Gypsum")(CaSO_(4).2H_(2)O) underset(373 K)overset("heat")rarr underset("Plaster of paris")(CaSO_(4). ½H_(2)O) + H_(2)O`