What is the chemical formula for Plaster of Paris ? How is it prepared ? State the common and chemical names of the compound formed when Plaster of Paris is mixed with water.

Explanation

The chemical formula for Plaster of Paris `CaSO_(4).(1)/(2) H_(2)O` It is prepared by heating gypsum at 373 K as shown by the following equation :
`underset("Gypsum")(CaSO_(4).2H_(2)O) overset(373 K)underset(Delta)rarr underset("Plaster of Paris")(CaSO_4 . (1)/(2)H_2O +(3)/(2))H_2O`
When Plaster of Paris is mixed with water. gypsum (common name) if formed again. Chemically it is known as calcium sulphate dihyrate.
`CaSO_(4).(1)/(2) H_(2)O + 3/2 H_(2)O rarr underset("Gypsum" )(CaSO_(4)2H_(2)O)`