Question

What is meant by hard water?

Answer 1

Hint: Water is said to be hard when it contains certain compounds that disrupt the normal behaviour of water. The compounds it contains are in the form of mineral ions. These mineral ions are soluble in water which makes them different from soft water.

Complete answer:
The hardness of water is because it shows the presence of chlorides, bicarbonates, and sulphates of calcium and magnesium. These compounds are soluble in water. The distinguishing property of hard water is that it does not lather with soap. There is no formation of a white foamy substance when soap mixes with hard water.
Hard water is formed when the normal water seeps through deposits of limestone or chalk which are made up of carbonates of calcium and magnesium.
Hard is classified into two types:
-Permanent hard water-
In Permanent hard water, the hardness cannot be eliminated by heating or boiling. It consists of salts of calcium and magnesium in the form of sulphates and chlorides. Treating hard water with washing soda can form insoluble carbonates of sulphides and chlorides of calcium and magnesium which can be filtered. This way hard water can be converted to soft water.
-Temporary hard water-
Temporary hard water means that this water can be converted to soft water by certain processes. It shows the presence of Magnesium and calcium carbonates. The hardness of the water can be eliminated by heating the water. The bicarbonates of calcium and magnesium are converted to carbonates. The formed carbonates of calcium and magnesium can be removed by filtration to obtain pure water.

Note:
A distinguishing feature of hard water is that it can feel dry on the skin. It has a very metallic and dry taste. The use of hard water forms scum rings in the bathroom as the soap doesn’t lather with it. It also isn’t very effective in cleaning clothes due to its ability to leave stains on linen.