Download Aptitude Crack
img not found img not found

Chemical Process

Q1:

Calcination of gypsum produces

A plaster of paris

B salt cake

C nitre cake

D lime

ANS:A - plaster of paris

Calcination of gypsum produces plaster of Paris for several reasons:

1. Chemical Process:

  • Heating Reaction: When gypsum (calcium sulfate dihydrate, CaSO₄·2H₂O) is heated to about 150-180 °C, it undergoes calcination, losing water to form calcium sulfate hemihydrate (CaSO₄·½H₂O), known as plaster of Paris.

2. Water Loss:

  • Dehydration: The process involves the removal of two water molecules from the gypsum structure, leading to a powdery form that can rehydrate easily.

3. Rehydration Properties:

  • Setting Ability: Plaster of Paris can be mixed with water to form a paste that sets quickly upon hardening, making it useful for casting molds, making sculptures, and in construction applications.

4. Versatile Applications:

  • Construction and Art: It is widely used in construction for making decorative elements, as well as in art for creating sculptures and molds due to its smooth finish and ease of use.

5. Temperature Control:

  • Controlled Calcination: The process is carefully controlled to ensure the proper formation of plaster of Paris without converting it into anhydrite (CaSO₄) by excessive heating.

Summary:

In summary, calcination of gypsum produces plaster of Paris through the dehydration of calcium sulfate dihydrate, resulting in a versatile material that sets quickly when mixed with water, widely used in construction and artistic applications.



img not found
img

For help Students Orientation
Mcqs Questions

One stop destination for examination, preparation, recruitment, and more. Specially designed online test to solve all your preparation worries. Go wherever you want to and practice whenever you want, using the online test platform.