Hard Water

Hard Water

Introduction to Hard water

Water is the most important compound that is needed for the survival of life on earth. Water is present in the oceans, rivers, ponds, lakes, glaciers etc. Water is also obtained by collecting the rainwaters. Rainwater is considered pure water because it does not contain any salt dissolved in it though there are dissolved gases present. Water is further classified as hard water and soft water.

  • Soft water: It lathers with soap. Water which is obtained from the rains is soft water. This water is suitable for household purposes for example laundry and cleaning.
  • Hard water: It is known as hard water because of the presence of salts of calcium and magnesium. Hard water does not lather with soap instead forms a precipitate.

What is Hard Water?

Hard water has high mineral content. Hard water is formed when water percolates through the deposits of chalk and limestone which are made up of magnesium and calcium carbonates. It does not lather with soap, so it is not suitable for laundry purposes. Hard water is harmful to the boilers as the deposition of salts occurs which reduces the efficiency of the boiler. Hard water is safe to drink, but using over a long interval of time can lead to many problems like:  

  • Strains in skins
  • Water appliances work harder which results in higher water bills.  
  • Spots appear on clothes and linens.  

Classification of Hard Water

Hard water can be further classified into two types: temporary hard water and permanent hard water.

  • Temporary hardness: The presence of magnesium and calcium carbonates in water makes it temporarily hard. In this case, the hardness of water can be removed by boiling the water. When we boil water the soluble salts of Mg(HCO3)2 is converted to Mg(OH)2 which is insoluble and hence gets precipitated and is removed. After filtration, the water we get is soft water.
  • Permanent hardness: When the soluble salts of magnesium and calcium are present in the form of chlorides and sulfides in water, we call it permanent hardness because this hardness cannot be removed by boiling. We can remove this hardness by treating the water with washing soda. Insoluble carbonates are formed when washing soda reacts with the sulfide and chloride salts of magnesium and calcium. And thus hard water is converted to soft water.

Signs of Hard Water

Signs of Hard Water

Strains appearing in the shower

  • Linens and clothes look dull and feel rough.
  • Ugly stains on white porcelain and scale buildup on faucets
  • Low water pressure from showers due to clogged pipes.
  • Chalky, white residue or spots appear on dishes.

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Practise This Question

Which of the following configuration corresponds to an alkaline earth metal