Plaster of Paris

Plaster of Paris is a widely used chemical compound that is extensively used in sculpting materials and gauze bandages.

The natural form of the Plaster of Paris is the mineral basanite.

Plaster of Paris is a white powder consisting of calcium sulphate hemihydrate.

Another name of plaster of Paris is Gypsum plaster. 

The name "plaster of Paris" came from the fact that it was originally made by heating gypsum from a large deposit at Montmartre, a hill in the north end of Paris. 

Plaster of Paris is stored in moisture-proof containers, due to the presence of moisture can cause slow setting of plaster of Paris by bringing about its hydration, and hydration will make it useless after some time. 

Plaster of Paris is a white powdery chemical compound that is hydrated calcium sulphate that is usually obtained by calcining gypsum. 

While we have seen many applications of this material in our everyday lives, if we try to understand its chemistry, we will find that it is a white powdery chemical compound that is hydrated calcium sulphate that is usually obtained by calcining gypsum. 

To put it another way, Plaster of Paris is often manufactured of heated gypsum at a high temperature.

The chemical formula of Plaster of Paris is expressed as CaSO4. ½ H2O.

Gypsum, CaSO4.2H2O (s) on heating at 100°C (373K) gives CaSO4. ½ H2O and 3/2 H2O

CaSO4. ½ H2O is plaster of paris.

 heat ${\displaystyle {\ce {->}}}$ ${\displaystyle {\ce {CaSO4.1/2H2O + 1 1/2H2O}}}$ 

CaSO4. ½ H2O means two formula units of CaSO4 share one molecule of water.

Uses – 

Plaster of Paris used for making surfaces like the walls of a house smooth before painting them and for making ornamental designs on the ceilings of houses and other buildings.

Plaster of Paris used for making toys, decorative materials, cheap ornaments, cosmetics, black-board, chalk and casts for statue.

Plaster of Paris an orthopedic cast is used in hospitals for setting fractured bones in the right position to ensure correct healing and avoid nonunion. It keeps the fractured bone straight. 

Plaster of Paris is mixed with a proper quantity of water and applied around the fractured limbs it sets into a hard mass, In this way it keeps the bone joints in a fixed position. 

Plaster of Paris is also for making casts in dentistry.