How does washing soda act in softening hard water?
Answer and explanation
Correct answer: It removes calcium and magnesium ions as insoluble carbonates
Hardness is mainly caused by dissolved calcium and magnesium ions. Washing soda, sodium carbonate (Na₂CO₃), supplies carbonate ions that react with them to form insoluble precipitates such as calcium carbonate and magnesium carbonate. These precipitates can be separated, so the concentration of hardness-causing ions decreases. It does not acidify water, produce hydrogen gas, or destroy sodium ions.
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?
Hardness is mainly caused by dissolved calcium and magnesium ions. Washing soda, sodium carbonate (Na₂CO₃), supplies carbonate ions that react with them to form insoluble precipitates such as calcium carbonate and magnesium carbonate. These precipitates can be separated, so the concentration of hardness-causing ions decreases. It does not acidify water, produce hydrogen gas, or destroy sodium ions.
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.
