What is the chemical formula of plaster of paris?

What is the chemical formula of plaster of paris?

1. A. Ca(OH)2
2. B. CaSO4. 1/2H2O
3. C. CaO
4. D. CaSO4. 2H2O

Answer: B. CaSO4. 1/2H2O

Plaster of Paris is also referred to as gypsum plaster. The chemical formula of plaster of Paris is written as CaSO₄·1/2H₂O.

• Ca(OH)2: This is the chemical formula for calcium hydroxide.
• CaO: This is the chemical formula for calcium oxide.
• CaSO4. 2H2O: This is the chemical formula for gypsum, the mineral from which plaster of paris is made. Plaster of paris is actually a partially dehydrated form of gypsum, hence the half molecule of water in its formula.