5. Complete Activity 1.5 (Page 8).
- Take about 2 g ferrous sulphate crystals in a dry boiling tube.
- Note the colour of the ferrous sulphate crystals.
- Heat the boiling tube over the flame of a burner or spirit lamp as shown in Fig. 1.4.
- Observe the colour of the crystals after heating.
Answer:
Aim: To heat the boiling tube containing ferrous sulphate crystals, note the observations and conclude.
Materials Required: 2 g ferrous sulphate crystals, boiling tube, Bunsen burner.
Procedure:
(i) 2 g ferrous sulphate crystals are taken in a dry boiling tube and the colour of the crystals are noted.
(ii) The boiling tube is held over the flame of the burner and heated. The colour of the crystals are observed after heating.
Observations:
- Initially the colour of the ferrous sulphate crystals was green.
- The colour changes to reddish-brown on heating.
- Gas was evolved during heating.
- An odour is also noticed.
Conclusions:
- Ferrous sulphate changes colour from green to reddish-brown because a reaction has taken place.
- The evolved gas and characteristic odour of sulphur further indicate that a reaction has taken place.
- Ferrous sulphate on heating decomposes to reddish ferric oxide (Fe2O3), and gases sulphur dioxide (SO2) and sulphur trioxide (SO3).
- This reaction in which a single substance decomposes into simpler substances on heating is called a thermal decomposition reaction. The equation is shown below:
2FeSO4(s) + Heat —> Fe2O3(s) + SO2(g) + SO3(g)
“5. Complete Activity 1.5 (Page 8).
Observe the colour of the crystals after heating.
Take about 2 g ferrous sulphate crystals in a dry boiling tube.
Note the colour of the ferrous sulphate crystals.
Heat the boiling tube over the flame of a burner or spirit lamp as shown in Fig. 1.4.” – Solved.
Related Links:
Solution to Group Activity
Solution to Activity 1.1
Solution to Activity 1.2
Solution to Activity 1.3
Solution to Activity 1.4
Solution to Activity 1.5
Solution to Activity 1.6
Solution to Activity 1.7
Solution to Activity 1.8
Solution to Activity
Solution to Activity 1.9
Solution to Activity 1.10
Solution to Activity 1.11
