Plaster of Paris (Uses) MCQs Quiz | Class 10
This quiz covers Class X Science (Code 086), Unit I: Chemical Substances – Nature and Behaviour, focusing on Plaster of Paris. Topics include its chemical formula, preparation, properties, and uses in casts, molds, and construction. Test your understanding, view your score, and download the PDF solution.
Topic Overview
Plaster of Paris (POP) is a white powdery chemical compound known as Calcium Sulphate Hemihydrate. Its formula is CaSO4.1/2H2O. It is prepared by heating Gypsum (CaSO4.2H2O) at 373 K (100 degrees Celsius). If heated above this temperature, it loses all water of crystallization and becomes dead burnt plaster (anhydrous calcium sulphate).
The remarkable property of Plaster of Paris is that on mixing with water, it changes into a hard solid mass (Gypsum) within half an hour, releasing heat. This setting property makes it extremely useful in various fields.
Key Uses
- Medical: Used by doctors for supporting fractured bones in the right position to ensure correct healing (plaster casts).
- Construction: Used for making smooth surfaces on walls and ceilings before painting. It is also used for making ornamental designs on ceilings (false ceilings).
- Decoration & Art: Widely used for making toys, statues, casts for statues, and decorative materials due to its ability to capture fine details from molds.
- Fireproofing: Used as a fireproofing material in buildings.
- Laboratory: Used for sealing air-gaps in apparatus to make them airtight.
Chemical Reaction (Setting of POP)
When Plaster of Paris is mixed with water, it rehydrates to form Gypsum:
CaSO4.1/2H2O + 1 1/2 H2O -> CaSO4.2H2O (Gypsum)
Quick Revision Facts
| Property | Detail |
|---|---|
| Chemical Name | Calcium Sulphate Hemihydrate |
| Common Name | Plaster of Paris |
| Formula | CaSO4.1/2H2O |
| Storage | Moisture-proof container |
Extra Practice Questions
- 1. Why is the temperature controlled at 373 K during the preparation of Plaster of Paris?
- 2. Write the chemical equation for the preparation of Plaster of Paris from Gypsum.
- 3. Why should Plaster of Paris be stored in moisture-proof containers?
- 4. What happens if Plaster of Paris is heated above 373 K?
- 5. Differentiate between Gypsum and Plaster of Paris based on water of crystallization.
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