prepare a chart showing hardness of water its types and methods of removal of hardness
Answers
Answer:
What is Hard Water?
Hard water has high mineral content. It 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.
The hardness of 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 skin
Water appliances work harder resulting in higher water bills
Spots appear on clothes and linens
Types of Hardness of Water
The hardness of water can be classified into two types:
Temporary Hardness
Permanent Hardness
Temporary Hardness of Water:
The presence of magnesium and calcium carbonates in water makes it temporarily hard. In this case, the hardness in 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 of Water:
When the soluble salts of magnesium and calcium are present in the form of chlorides and sulphides 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 sulphide and chloride salts of magnesium and calcium and thus, hard water is converted to soft water.
Disadvantages of Hardness
Wastage of soap
Wastage of fuel
Formation of scales on metallic boilers.
⇒ Also Read: Heavy Water – Methods of Preparation and Properties
Remove Hardness of Water (Temporary)
By Boiling:
Soluble bicarbonates are converted into insoluble carbonates which are removed by filtration.
Reactions: Ca(HCO3)2 → ΔCalo3↓ + H2O + CO2
⇒ Mg(HCO3)2 → ΔMgCO3↓ + H2O + CO2
By Clarks Method:
Calcium hydroxide is Clark’s reagent. It removes the hardness of water by converting bicarbonates into carbonate.
Reaction: Ca(OH)2 + Ca(HCO3)2 → 2CaCO3↓ + 2H2O