Answer:
CaCO₃ built up in hot water pipes
Explanation:
The hardness of water is classified as;
Permanent Hard Water:
In this the mineral content cannot be removed by boiling. This water contains mainly following,
Calcium Sulfate CaSO₄
Calcium Chloride CaCl₂
Magnesium Sulfate MgSO₄
Magnesium Chloride MgCl₂
These salts does not precipitate out on heating water.
Temporary Hard Water:
In this water the mineral content can be removed by boiling. This water contains mainly following,
Calcium Bicarbonate Ca(HCO₃)₂
Calcium Carbonate CaCO₃
Magnesium Bicarbonate Mg(HCO₃)₂
Magnesium Carbonate MgCO₃
These salts does not precipitate out on heating water. i.e.
Ca(HCO₃)₂ -------heat------> CaCO₃ + CO₂ + H₂O
The CaCO₃ are formed in the form of scales.
Result:
Hence, we can say that that CaCO₃ built up in hot water pipes.
