Question

How will you distinguish: Temporary hard water and permanent hard water?

Answer 1

Hint: Bicarbonates, chlorides, and sulphates of calcium and magnesium cause hardness to the water. These salts are soluble in water and make the water not useful for drinking and washing purposes. Hardness is of two types according to the presence of salts. They are permanent hardness and temporary hardness.
Complete step by step answer:
- The differences between temporary and permanent hardness are as follows.

Temporary hardness	Permanent hardness
- It is due to the presence of bicarbonates of calcium and magnesium.	- It is due to the presence of chlorides and sulphates of calcium and magnesium.
- It is easily removable by boiling the water.	- It is removed by using some techniques called the zeolite method, ion-exchange process, reverse osmosis etc.
- Removal of temporary hardness is very cheap.	- Removal of permanent hardness causing salts is costly.
- It is also called as alkaline or carbonate hardness	- It is also called non-carbonate hardness.
- By boiling, carbonates are going to precipitate.	- By boiling, chlorides and sulphates won’t get precipitated.

\[Ca{{(HC{{O}_{3}})}_{2}}\xrightarrow{Boiling}CaC{{O}_{3}}+C{{O}_{2}}+{{H}_{2}}O\]
- Calcium bicarbonate on boiling the water converts into calcium carbonate precipitate, carbon dioxide gas and water.

Note: The total hardness of water is nothing but the addition of temporary hardness and permanent hardness.
Total hardness = Temporary hardness + Permanent hardness.
Due to the presence of hardness causing salts in the water some boiler troubles are going to rise in industries.