Question

Plaster of Paris was first found in Montmatre in Paris in the form of white rocks. Chemically, it can be obtained by heating gypsum carefully to about 373 K in a kiln. The temperature must be carefully controlled because at the higher temperatures, it gets completely dehydrated to form anhydrous calcium sulphate. It is very commonly used in surgical bandages for setting fractured bones. Is the chemical formula of Plaster of Paris actually correct?

Answer 1

Plaster of Paris is the hemihydrate form of Calcium sulphate $\left({\mathrm{CaSO}}_4·\frac{1}{2}{\mathrm{H}}_2\mathrm{O}\right)$.

Uses of POP:-

1. It is used in the Medical industry to support fractured bones.
2. It is used to make casts for statues and molds.
3. It is used to make Ornaments.

No, the chemical formula of Plaster of Paris written as ${\mathrm{CaSO}}_4·\frac{1}{2}{\mathrm{H}}_2\mathrm{O}$, is not actually correct as half water molecule cannot exist.

Thus, the chemical formula of POP must be represented as $2{\mathrm{CaSO}}_4·{\mathrm{H}}_2\mathrm{O}$