How does washing soda help soften hard water?
Answer and explanation
Correct answer: It removes calcium and magnesium ions as insoluble carbonates
Hard water contains dissolved calcium and magnesium ions, which interfere with soap and form scum. Washing soda, sodium carbonate (Na₂CO₃), supplies carbonate ions. These combine with calcium and magnesium ions to form insoluble calcium carbonate and magnesium carbonate precipitates, removing the troublesome ions from the water. Consequently, soap can lather more readily. It does not produce hydrogen, increase acidity, or destroy sodium ions, so option A correctly explains the softening process.
Frequently asked questions
What is the correct answer to this question?
It removes calcium and magnesium ions as insoluble carbonates
Why is this the correct answer?
Hard water contains dissolved calcium and magnesium ions, which interfere with soap and form scum. Washing soda, sodium carbonate (Na₂CO₃), supplies carbonate ions. These combine with calcium and magnesium ions to form insoluble calcium carbonate and magnesium carbonate precipitates, removing the troublesome ions from the water. Consequently, soap can lather more readily. It does not produce hydrogen, increase acidity, or destroy sodium ions, so option A correctly explains the softening process.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
