Question

Which of the following salts has no water of crystallization?
A)Blue vitriol
B)Washing soda
C)Baking soda
D)Gypsum

Answer 1

To solve this question, we must follow these steps: first we need to understand the concept of water of crystallization. Then we must draw the molecular structures of the compounds given to us to compare and deduce the correct option form them.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us understand some important basic concepts.
Water of crystallization: Water of crystallization can be explained as the existence of water molecules in the molecular structures of certain salts. Water of crystallization is also known as the water of hydration. And the salts complexes thus formed with the water molecules are known as hydrates. The number of molecules of water is fixed in the formula of a unit of salt.
Now, let us discuss about the compounds given to us:
1.Blue vitriol: Blue Vitriol is nothing but a salt of copper. More specifically, the chemical name of the salt is copper sulphate and its molecular formula is given as $CuS{O_4}.5{H_2}O$
2.Washing soda: Washing soda is nothing but the carbonate salt of sodium. The chemical name of washing soda is sodium carbonate and its molecular formula is $N{a_2}C{O_3}.10{H_2}O$
3.Baking soda: Baking soda is a hydrogen carbonate salt of sodium. The chemical name of baking soda is sodium bicarbonate and the chemical formula for baking soda is $NaHC{O_3}$ .
4.Gypsum: Gypsum is the sulphate salt of calcium. The chemical name for gypsum is calcium sulphate and the chemical formula is $CaS{O_4}.2{H_2}O$
From the data above, we can observe that baking soda is the only compound without any water of crystallization.
Hence, Option C is the correct option

Note: This phenomenon of water of crystallization happens when we form purified crystals form the corresponding aqueous solution. The crystals thus formed do not contain contaminants of any sort. Although, these crystals respond to heat.