Why does the hardness of water render it unfit for use in a
(i) boiler (ii) for washing purposes.
Why does the hardness of water render it unfit for use in a
(i) boiler (ii) for washing purposes.
(i) boiler
The hard water contains calcium and magnesium.When we boil hard water these metals(Ca and Mg) form a hard covering on the utensil on which it is boiled.
Steam is usually made in boilers which are made of a number of narrow copper tubes surrounded by fire. As the cold water enters these tubes, it is immediately changed into steam, while the dissolved solids incapable of changing into vapour deposit on the inner walls of the tubes. This goes on and makes the bore of the tubes narrower. The result is that less water flows through the tubes at one time and less steam is produced. When the bore of the tube becomes very narrow, the pressure of the steam increases so much that at times the boiler bursts.
(ii) for washing purposes.
Hard water doesn't form lather or foam with soap. Hence hard water is unfit for washing.
If hard water is used, calcium and magnesium ions of the water combine with the negative ions of the soap to form a slimy precipitate of insoluble calcium and magnesium usually called soap curd (scum).
Formation of soap curd will go on as long as calcium and magnesium ions are present. Till then, no soap lather will be formed and cleaning of clothes or body will not be possible. Moreover, these precipitates are difficult to wash from fabrics and sometimes form rusty spots if iron salts are present in water.
(i) boiler
The hard water contains calcium and magnesium.When we boil hard water these metals(Ca and Mg) form a hard covering on the utensil on which it is boiled.
Steam is usually made in boilers which are made of a number of narrow copper tubes surrounded by fire. As the cold water enters these tubes, it is immediately changed into steam, while the dissolved solids incapable of changing into vapour deposit on the inner walls of the tubes. This goes on and makes the bore of the tubes narrower. The result is that less water flows through the tubes at one time and less steam is produced. When the bore of the tube becomes very narrow, the pressure of the steam increases so much that at times the boiler bursts.
(ii) for washing purposes.
Hard water doesn't form lather or foam with soap. Hence hard water is unfit for washing.
If hard water is used, calcium and magnesium ions of the water combine with the negative ions of the soap to form a slimy precipitate of insoluble calcium and magnesium usually called soap curd (scum).
Formation of soap curd will go on as long as calcium and magnesium ions are present. Till then, no soap lather will be formed and cleaning of clothes or body will not be possible. Moreover, these precipitates are difficult to wash from fabrics and sometimes form rusty spots if iron salts are present in water.
