Question

Give balanced equations to show how permanent hardness in water can be removed by addition of washing soda.

Answer 1

Removal of permanent hardness in water by adding washing soda : CaCl₂ or CaSO₄ present in permanent hard water exchanges the ions and forms CaCO₃ which being in soluble can be filtered.

\[\ce{\underset{\text{Washing soda}}{Na2CO3} + \underset{\text{Present in hard work}}{CaSO4} -> CaCO3↓ + Na2SO4}\]

\[\ce{Na2CO3 + CaCl2 -> CaCO3↓ + 2NaCl}\]