Question

The temporary hardness of water due to calcium carbonate can be removed by adding

• A. CaCО3
• B. CaCl2
• C. HCI
• D. Ca(OН)2

Answer 1

Answer:

D. Ca(OН)2

The temporary hardness of water due to calcium bicarbonate is removed by boiling.

Answer: Boiling the water

$Ca(HCO3)2→boilingCaCO3↓+CO2+H2O\text{Ca(HCO}_3)_2 \xrightarrow{\text{boiling}} \text{CaCO}_3\downarrow + CO_2 + H_2O$

The insoluble calcium carbonate (CaCO₃) precipitates and can be removed by filtration.

Note: Strictly speaking, temporary hardness is due to calcium bicarbonate, not calcium carbonate.