Sodium carbonate (Na₂CO₃), also known as washing soda, removes water hardness by precipitating the dissolved calcium and magnesium ions that cause hardness.
Here's a breakdown of the process:
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Solubility and Carbonate Ions: Sodium carbonate is soluble in water. When it dissolves, it releases carbonate ions (CO₃²⁻) into the water.
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Reaction with Hardness-Causing Ions: The carbonate ions then react with the calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) that are dissolved in the hard water. These ions are responsible for both temporary and permanent hardness.
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Formation of Insoluble Precipitates: This reaction results in the formation of insoluble precipitates: calcium carbonate (CaCO₃) and magnesium carbonate (MgCO₃). These precipitates are solids that no longer contribute to the water's hardness.
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Removal of Precipitates: These insoluble carbonates can then be removed through filtration or settling, effectively softening the water.
In summary, sodium carbonate softens water by introducing carbonate ions that react with calcium and magnesium ions, forming insoluble precipitates that can be easily removed.
