15. Complete Activity 2.15 (Page 32)
- Heat a few crystals of copper sulphate in a dry boiling tube.
- What is the colour of the copper sulphate after heating?
- Do you notice water droplets in the boiling tube? Where have these come from?
- Add 2-3 drops of water on the sample of copper sulphate obtained after heating.
- What do you observe? Is the blue colour of copper sulphate restored?
Answer:
Aim: To heat copper sulphate crystals in a dry boiling tube, add 2-3 drops of water after heating and note the observations in each case and conclude.
Materials Required: Copper sulphate crystals, boiling tube, Bunsen burner, water.
Procedure:
(i) Take some copper sulphate crystals in a dry boiling tube
(ii) Heat the tube using a burner. Note the observations.
(iii) Add 2-3 drops of water on the copper sulphate crystals post-heating. Note the observations.
Observations:
- When you heat the copper sulphate crystals, the blue colour of the crystals changes to white.
- When water is added post-heating, the blue colour of the crystals is restored.
Conclusions:
- Copper sulphate crystals which seem to be dry contain water of crystallisation. Five molecules of water are present per molecule of copper sulphate.
- When the crystals are heated, this water is removed and the salt turns white.
- On adding water, blue colour of the crystals reappears because the salt becomes hydrated again.
“15. Complete Activity 2.15 (Page 32)
What do you observe? Is the blue colour of copper sulphate restored?
Heat a few crystals of copper sulphate in a dry boiling tube.
What is the colour of the copper sulphate after heating?
Do you notice water droplets in the boiling tube? Where have these come from?
Add 2-3 drops of water on the sample of copper sulphate obtained after heating.” – Solved.
Redlated Links:
Solution to Group Activity
Solution to Activity 2.1
Solution to Activity 2.2
Solution to Activity 2.3
Solution to Activity 2.4
Solution to Activity 2.5
Solution to Activity 2.6
Solution to Activity 2.7
Solution to Activity 2.8
Solution to Activity 2.9
Solution to Activity 2.10
Solution to Activity 2.11
Solution to Activity 2.12
Solution to Activity 2.13
Solution to Activity 2.14
Solution to Activity 2.15
