Name the sodium compound which is used for softening hard water.

A: The sodium compound commonly used for softening hard water is Sodium Carbonate (Na2CO3), also known as Washing Soda. Sodium Carbonate removes calcium and magnesium ions, which cause water hardness, through a process called precipitation:

Ca2+ + Na2CO3 → CaCO3 (precipitate) + 2Na+ Mg2+ + Na2CO3 → MgCO3 (precipitate) + 2Na+

This reaction forms insoluble calcium and magnesium carbonates, which can be easily removed, resulting in softened water. Sodium Carbonate is effective in removing permanent hardness of water and is widely used in: Laundry Water treatment plants Industrial processes.

It’s an essential component in many water softening products and detergents.