what is hardness of water and how sodium carbonate helps in removing it

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Solution

Hardness of water means the presence of calcium and magnesium salts such as calcium carbonate, calcium bicarbonate, calcium sulphate, magnesium carbonate, magnesium bicarbonate, magnesium sulphate in water. Hard water does not form lather with soap and an insoluble deposit called scum is formed. The Ca⁺² and Mg⁺² ions react with the strearate ions in soap, forming an insoluble scum before lather is produced. Hard water causes damage to water pipes and boilers and kettles in industries.

By using sodium carbonate, calcium carbonate is formed as per the following equation

CaSO₄ + Na₂CO₃ ----------> CaCO₃+ Na₂SO₄
CaCO₃ is insoluble and hence can be removed by filtration. The sodium ion which replaced the calcium ion does not react with soap or detergent and scum formation is prevented.

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Similar questions

Q. Washing soda helps in removing the permanent hardness of water.

Q. Assertion (A): Hardness of water is removed by treatment with sodium carbonate.
Reason (R): Sodium carbonate reacts with soluble magnesium and calcium chloride to form water soluble compounds.

Chemical ‘A’ is used for water softening to remove temporary hardness. ‘A’ reacts with sodium carbonate to generate caustic soda. When carbon dioxide is bubbled through ‘A’, it turns cloudy. What is the chemical formula of ‘A’ ?

What is the permanent hardness of water? How can it be removed?

Q. Chemical

A

is used for water softening to remove temporary hardness.

A

reacts with sodium carbonate to generate caustic soda. When

C O_{2}

is bubbled through a solution of

A

, it turns cloudy. What is the chemical formula of

A

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