Plaster of paris can be obtained from the calcination of:
🔥 Understanding Calcination and Raw Materials
Calcination is a process of heating a solid material to drive off volatile components, such as water or carbon dioxide. Different raw materials yield different products when calcined. Plaster of Paris is a well-known building material created by the careful heating of a specific mineral.
🔬 Detailed Analysis of the Options
B. Gypsum
This is the correct answer. Plaster of Paris is produced by heating gypsum (Calcium Sulphate Dihydrate, CaSO₄·2H₂O) to a temperature of about 120-150°C (393-423 K). This process drives off about 75% of the water of crystallization, resulting in Calcium Sulphate Hemihydrate (CaSO₄·½H₂O), the chemical name for Plaster of Paris.
A. Lime stone
This is incorrect. The calcination of limestone (Calcium Carbonate, CaCO₃) produces quicklime (Calcium Oxide, CaO), not Plaster of Paris.
C. Dolomite
This is incorrect. Dolomite is a calcium magnesium carbonate. Calcining it produces a mixture of calcium oxide and magnesium oxide, used to make dolomitic lime.
D. Bauxite
This is incorrect. Bauxite is the primary ore for aluminum. It is also used in the manufacture of high-alumina cement, but not Plaster of Paris.
📊 Summary: Calcination Products
| Raw Material | Chemical Formula | Product of Calcination |
|---|---|---|
| Gypsum | CaSO₄·2H₂O | Plaster of Paris (CaSO₄·½H₂O) |
| Limestone | CaCO₃ | Quicklime (CaO) |
| Dolomite | CaMg(CO₃)₂ | Dolomitic Lime (CaO + MgO) |
| Bauxite | Al₂O₃·nH₂O | Alumina (for Aluminum production) |
💡 Study Tips
- Gypsum gives Plaster: This is a fundamental association in building materials. Remember "Gypsum -> Plaster".
- Sulphate vs. Carbonate: Gypsum is a sulphate (CaSO₄). Limestone is a carbonate (CaCO₃). This chemical difference leads to completely different products upon heating.
- Think of Medical Casts: The white powder used to make medical casts for broken bones is Plaster of Paris. This common application can help you remember the material.