Temporary Hardness:
Temporary hardness refers to the type of hardness that can be easily removed by boiling the water. It is caused by the presence of bicarbonate ions of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2) in the water. Temporary hardness is also known as carbonate hardness.

Causes of Temporary Hardness:
Temporary hardness occurs when water comes in contact with limestone or chalk deposits, which contain calcium and magnesium carbonates. These carbonates dissolve in water to form bicarbonate ions. The presence of bicarbonate ions makes the water hard.

Removal of Temporary Hardness:
Temporary hardness can be removed by boiling the water. When water is boiled, the bicarbonate ions decompose and release carbon dioxide gas (CO2) and water (H2O). The equation for the decomposition of calcium bicarbonate is as follows:

Ca(HCO3)2 → CaCO3 + CO2 + H2O

The equation for the decomposition of magnesium bicarbonate is:

Mg(HCO3)2 → MgCO3 + CO2 + H2O

The calcium carbonate (CaCO3) and magnesium carbonate (MgCO3) formed during the boiling process are insoluble. Therefore, they precipitate out of the water and can be easily removed by filtration or sedimentation.

Significance of Temporary Hardness:
Temporary hardness does not cause any significant problems in most domestic and industrial applications. However, it can cause scaling in boilers, pipes, and heating systems. The formation of scale reduces the efficiency of these systems and increases maintenance costs. Therefore, it is necessary to remove temporary hardness in certain situations.

Conclusion:
Temporary hardness is the type of hardness caused by the presence of bicarbonate ions of calcium and magnesium in water. It can be easily removed by boiling the water, which causes the bicarbonate ions to decompose and precipitate as insoluble carbonates. While temporary hardness does not pose major problems in most cases, it can cause scaling in certain industrial applications.