Permanent hardness of water is primarily due to the presence of calcium and magnesium ions, typically in the form of calcium sulfate (CaSO₄) and magnesium sulfate (MgSO₄). Washing soda, or sodium carbonate (Na₂CO₃), can be used to remove this type of hardness through a precipitation reaction. Here's the equation:
Ca²⁺(aq) + Na₂CO₃(aq) → CaCO₃(s) + 2Na⁺(aq)
In this reaction:
Calcium ions (Ca²⁺) from calcium sulfate in the water react with sodium carbonate (Na₂CO₃).
A white precipitate of calcium carbonate (CaCO₃) is formed, which is insoluble in water and settles down.
The sodium ions (Na⁺) remain in the water as sodium ions are highly soluble and do not contribute to water hardness.
The removal of calcium ions as calcium carbonate results in a reduction of water hardness, making the water "softer."
The precipitated calcium carbonate can then be filtered out, leaving behind water with reduced hardness.
Answers & Comments
Permanent hardness of water is primarily due to the presence of calcium and magnesium ions, typically in the form of calcium sulfate (CaSO₄) and magnesium sulfate (MgSO₄). Washing soda, or sodium carbonate (Na₂CO₃), can be used to remove this type of hardness through a precipitation reaction. Here's the equation:
Ca²⁺(aq) + Na₂CO₃(aq) → CaCO₃(s) + 2Na⁺(aq)
In this reaction:
Calcium ions (Ca²⁺) from calcium sulfate in the water react with sodium carbonate (Na₂CO₃).
A white precipitate of calcium carbonate (CaCO₃) is formed, which is insoluble in water and settles down.
The sodium ions (Na⁺) remain in the water as sodium ions are highly soluble and do not contribute to water hardness.
The removal of calcium ions as calcium carbonate results in a reduction of water hardness, making the water "softer."
The precipitated calcium carbonate can then be filtered out, leaving behind water with reduced hardness.