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Question
Both temporary & permanent hardness in water can be removed by addition of washing soda. Give balanced equations for the same.
Solution
Using washing soda, removal of:
(i) Temporary hardness
\[\ce{\underset{\text{washinng soda}}{Na2CO3} +\underset{\text{temporary hardness}}{Ca(HCO3)2} -> CaCO3↓ + 2NaHCO3}\]
\[\ce{\underset{\text{washinng soda}}{Na2CO3} +\underset{\text{temporary hardness}}{ Mg(HCO3)2} -> MgCO3↓ + 2NaHCO3}\]
(i) Permanent hardness
\[\ce{\underset{\text{washing soda}}{Na2CO3} +\underset{\text{permanent hardness}}{CaSO4} ->Na2SO4 +\underset{\text{insoluable}}{CaCO3↓}}\]
\[\ce{\underset{\text{washing soda}}{Na2CO3} +\underset{\text{permanent hardness}}{MgCL2} -> \underset{\text{insoluable}}{MgCO3↓} + 2NaCl}\]
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