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Question
Differentiate between hydrated and anhydrous crystals with examples. State three defined changes that occur when hydrated copper sulphate is heated.
Solution
Difference between hydrated and anhydrous crystals:
| Hydrated crystal | Anhydrous crystal |
| (i) Contains fixed number of water molecules. | (i) Does not contains any fixed number of water molecules |
| (ii) CuSO4, 5H2O, FeSO4.7H2O are examples. | KNO3, K2SO4 are examples. |
Three defined changes: When CuSO4. 5H2O is heated take place are: (blue).
- Colour changes from blue to colourless.
- Changed to AMORPHOUS white powder
- Geometric shape vanishes
- On cooling and adding water colour restores but crystalline does not shape.
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