Identify the metal sulphide used to prepare hydrogen sulphide gas, write the equation for its reaction with hydrochloric acid, and describe a chemical test for the gas.

Step 1: Answer Question 20.

a) The metal sulphide that can be used in preparing hydrogen sulphide gas is iron(II) sulphide.

b) The equation for the reaction is:

$$\boxed{\text{FeS}(\text{s}) + 2\text{HCl}(\text{aq}) \to \text{FeCl}_2(\text{aq}) + \text{H}_2\text{S}(\text{g})}$$

c) One chemical test for hydrogen sulphide gas is to expose it to lead(II) acetate paper. The paper will turn black due to the formation of lead(II) sulphide.