Chemicals required:
- Hydrochloric acid (HCl)
- Ferrous sulphide (FeS)
- Dilute sulphuric acid (H2SO4)
- Apparatus: gas generator, delivery tube, gas jar, and water trough.

Balanced chemical equation:
FeS + 2HCl → FeCl2 + H2S

Collection of the gas:
1. Set up the gas generator by placing a small flask or test tube containing ferrous sulphide (FeS) in a gas jar. The gas jar should be filled with water and inverted in a water trough.
2. Add dilute sulphuric acid (H2SO4) to the gas generator, which will react with the ferrous sulphide to produce hydrogen sulphide gas (H2S) according to the chemical equation above.
3. As the reaction proceeds, the hydrogen sulphide gas will be released and collected in the gas jar. It displaces the water in the jar and fills it with the gas.
4. The gas jar should be kept inverted in the water trough to prevent the escape of the gas.
5. Once a sufficient amount of gas has been collected, remove the gas jar from the water trough and cover it with a glass plate or stopper to prevent the gas from escaping.
6. The collected hydrogen sulphide gas can then be used for various experiments or observations.

Explanation:
- Hydrogen sulphide gas (H2S) can be prepared in the laboratory by the reaction between ferrous sulphide (FeS) and hydrochloric acid (HCl). This reaction can be represented by the balanced chemical equation: FeS + 2HCl → FeCl2 + H2S.
- The gas is generated by placing a small amount of ferrous sulphide in a gas generator, which is a flask or test tube. The gas generator is then connected to a gas jar filled with water and inverted in a water trough.
- Dilute sulphuric acid is added to the gas generator, which reacts with the ferrous sulphide to produce hydrogen sulphide gas. The gas is released and collects in the gas jar, displacing the water.
- The gas jar should be kept inverted in the water trough to prevent the escape of the gas. Once a sufficient amount of gas has been collected, the gas jar can be removed and covered to prevent the gas from escaping.
- Hydrogen sulphide gas is colorless and has a distinct odor of rotten eggs. It is toxic and flammable, so it should be handled with caution.
- The collected hydrogen sulphide gas can be used for various experiments or observations, such as testing for the presence of sulphide ions in a solution or studying the properties of the gas.