Blue copper sulphate becomes white on heating. What causes this change?
Answer and explanation
Correct answer: Water of crystallisation is removed
The governing concept is dehydration of a hydrated salt. Blue copper sulphate is CuSO₄·5H₂O, whose blue colour is associated with its water of crystallisation. On heating, this water is removed and anhydrous CuSO₄ forms, which is white: CuSO₄·5H₂O → CuSO₄ + 5H₂O. Hence option A is correct; copper does not become gold and sulphate does not turn into oxygen.
Frequently asked questions
What is the correct answer to this question?
Water of crystallisation is removed
Why is this the correct answer?
The governing concept is dehydration of a hydrated salt. Blue copper sulphate is CuSO₄·5H₂O, whose blue colour is associated with its water of crystallisation. On heating, this water is removed and anhydrous CuSO₄ forms, which is white: CuSO₄·5H₂O → CuSO₄ + 5H₂O. Hence option A is correct; copper does not become gold and sulphate does not turn into oxygen.
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.
