Question

Which one of the following does not contain water in alkali crystallization?
1. Baking soda
2. Blue vitriol
3. Washing soda
4. Gypsum

Answer 1

Correct Answer - Option 1 : Baking soda

The correct answer is Baking soda.

• Baking soda does not contain water of crystallization.
• The water of crystallization means having a fixed number of molecules present in one formula of a unit of salt. 
  • e.g ​Blue vitriol (CuSO4.5H20)
• The chemical formula of baking soda is NaHCO₃.
  • Its formula does not show any association with water molecules.
• Baking soda is commercially manufactured on a large scale by the ammonia-soda Solvay process, named after Ernest Solvay, a Belgian industrial chemist.
• Nahcolite is naturally occurring sodium bicarbonate, and is extracted by "solution mining".

• The other three options contain water of crystallization.
  • Blue vitriol (CuSO₄.5H₂0)
  • Washing soda (Na₂CO₃ .1OH₂O)
  • Gypsum (CaSO₄.2H₂0)
• Baking soda is white amorphous powder whereas blue vitriol, and washing soda are salts.