Question

How is Gypsum different from Plaster of Paris?

Answer 1

The following points can explain the differences between Gypsum and Plaster of Paris:

• One of the biggest distinctions between gypsum and Plaster of Paris is that Gypsum has calcium sulphate dihydrate(${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$) , whereas Plaster of Paris has calcium sulphate hemihydrates(${\mathrm{CaSO}}_4.1/2{\mathrm{H}}_2\mathrm{O}$).
• Hence Plaster of Paris has $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$ mole of crystallization water whereas $2$ moles of crystallization water is present in Gypsum.
• When Gypsum is heated roughly $140-180°C$, the crystals of Plaster of Paris are obtained.