- Heat a few crystals of copper sulphate in a dry boiling tube.
- What is the colour of the copper sulphate after heating?
✅ Answer: White.
- Do you notice water droplets in the boiling tube? Where have these come from?
✅ Answer: Copper sulphate crystals contain water of crystallisation. When heated the crystals, this water is removed and the salt turns white.
- Add 2-3 drops of water to the sample of copper sulphate obtained after heating.
- What do you observe? Is the blue colour of copper sulphate restored?
✅ Answer: Copper sulphate crystals restore its blue colour.