Question
Download Solution PDFWhich one of the following sodium compounds is used for softening hard water?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct answer is Na2CO3.
Key Points
- The sodium compound is used for softening hard water. Washing soda or sodium carbonate is used for removing the permanent hardness of the water.
- Washing soda has a chemical formula Na2CO3.10H2O.
- It binds calcium and magnesium molecules in water.
- Water can be softened by adding sodium carbonate (washing soda) or bypassing the water through an ion-exchange column.
- For large-scale municipal operations, a process known as the lime-soda process is used to remove Ca2+ and Mg2+ from the water supply.
Additional Information
| Na2SO4 |
Sodium Sulphate Formula: Na2SO4 Molar mass: 142.04 g/mol Density: 2.66 g/cm³ Boiling point: 1,429 °C Melting point: 884 °C Soluble in: Water |
| NaOH |
Sodium Hydroxide Formula: NaOH Molar mass: 39.997 g/mol Density: 2.13 g/cm³ Boiling point: 1,388 °C IUPAC ID: Sodium hydroxide, Sodium oxidanide Soluble in: Water, Ethanol, Methanol |
| NaHCO3 |
Bicarbonate of Soda Formula: NaHCO₃ IUPAC ID: Sodium hydrogen carbonate Molar mass: 84.007 g/mol Density: 2.2 g/cm³ Molar entropy: 102 J/(mol⋅K) Soluble in: Water |
Last updated on Jun 25, 2025
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