Soap produces less lather in hard water. Why does adding washing soda improve lather formation?
Answer and explanation
Correct answer: It helps remove calcium and magnesium ions
Hard water contains Ca2+ and Mg2+ ions. These ions react with soap anions to form insoluble scum, so less soap remains available for lather. Washing soda, Na2CO3, supplies carbonate ions that precipitate calcium and magnesium as insoluble carbonates, softening the water. Hence option A is correct; the other choices do not describe softening or lather formation.
Frequently asked questions
What is the correct answer to this question?
It helps remove calcium and magnesium ions
Why is this the correct answer?
Hard water contains Ca2+ and Mg2+ ions. These ions react with soap anions to form insoluble scum, so less soap remains available for lather. Washing soda, Na2CO3, supplies carbonate ions that precipitate calcium and magnesium as insoluble carbonates, softening the water. Hence option A is correct; the other choices do not describe softening or lather formation.
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.
