Which one of the following is correct?

The setting of the plaster of Paris is the process of

The correct answer is hydration to yield another hydrate

Key Points

• The setting of the plaster of Paris is the process of hydration to yield another hydrate.
• Plaster of Paris is a powder made from gypsum, which is a naturally occurring mineral.
• When water is added to the plaster of Paris, it undergoes a chemical reaction called hydration, which results in the formation of a solid crystalline hydrate.
• The hydration reaction is the reverse of the dehydration of gypsum.
• The hardening and setting process starts about 10 minutes after mixing and is complete in approximately 45 minutes.

Additional Information

• Plaster of Paris (POP), quick-setting gypsum plaster consisting of a fine powder (calcium sulfate hemihydrate), which hardens when moistened and allowed to dry.
• It is also known as the Plaster of Paris because for the preparation of POP, the abundant gypsum was first found near the capital city of France i.e. Paris.
• The chemical formula of the Plaster of Paris is (CaSO4). 1/2 H2O.

The application of Plaster of Paris:

• It is used as a building material as a protective coating on walls and ceilings.
• It is used as a moulding and vesting agent for decorative elements.
• It is also used for aesthetic touch to the construction elements.
• It is also field as plaster in orthopaedics and as a filling material by dentists, etc.