Blue copper sulphate crystals turn white on heating. This change occurs due to removal of what?
Answer and explanation
Correct answer: Water of crystallisation
Blue copper sulphate crystals are hydrated copper sulphate, CuSO4·5H2O. The attached water molecules are called water of crystallisation and give the crystals their blue appearance. On heating, this water is driven off, producing anhydrous copper sulphate, CuSO4, which is white. The change is not caused by release of oxygen, copper metal, or sulphur dioxide. Adding water can restore the blue hydrated form, so A is correct.
Frequently asked questions
What is the correct answer to this question?
Water of crystallisation
Why is this the correct answer?
Blue copper sulphate crystals are hydrated copper sulphate, CuSO4·5H2O. The attached water molecules are called water of crystallisation and give the crystals their blue appearance. On heating, this water is driven off, producing anhydrous copper sulphate, CuSO4, which is white. The change is not caused by release of oxygen, copper metal, or sulphur dioxide. Adding water can restore the blue hydrated form, so A is correct.
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.
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