How is `H_(2)S` prepared in laboratory ?

Options

A. `FeS + H_(2)SO_(4)`
B. `FeSO_(4) + H_(2)SO_(4)`
C. `FeS + HCl`
D. Elemental `H_(2) +` elemental `S_(8)`

Answer

To prepare hydrogen sulfide (H₂S) in the laboratory, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The primary reactant for the preparation of hydrogen sulfide is ferrous sulfide (FeS). We will also need an acid, which can be either sulfuric acid (H₂SO₄) or hydrochloric acid (HCl).

2. **Choose the Acid**: Decide which acid to use. For this example, we will use sulfuric acid (H₂SO₄).

3. **Set Up the Reaction**: In a fume hood (due to the toxic nature of H₂S gas), take a small amount of ferrous sulfide (FeS) in a flask.

4. **Add the Acid**: Carefully add sulfuric acid (H₂SO₄) to the flask containing ferrous sulfide. The reaction will proceed as follows:
\[ \text{FeS} + \text{H}_2\text{SO}_4 \rightarrow \text{H}_2\text{S} + \text{FeSO}_4 \]

5. **Observe the Reaction**: As the reaction occurs, hydrogen sulfide gas (H₂S) will be produced. You may observe bubbling or effervescence as the gas is released.

6. **Collect the Gas**: The hydrogen sulfide gas can be collected by upward displacement of air or by using a gas jar. Ensure proper ventilation and safety measures are in place due to the toxicity of H₂S.

7. **Alternative Reaction**: If you choose to use hydrochloric acid (HCl) instead, the reaction would be:
\[ \text{FeS} + 2\text{HCl} \rightarrow \text{H}_2\text{S} + \text{FeCl}_2 \]

### Summary of the Reaction:
- **With Sulfuric Acid**:
\[ \text{FeS} + \text{H}_2\text{SO}_4 \rightarrow \text{H}_2\text{S} + \text{FeSO}_4 \]
- **With Hydrochloric Acid**:
\[ \text{FeS} + 2\text{HCl} \rightarrow \text{H}_2\text{S} + \text{FeCl}_2 \]