In Haber 's process of Ammonia synthesis the substance that acts as catalytic poison

Options

A. `Fe_(2)O_(3)`
B. `As_(2)O_(3)`
C. `CO_(1)`
D. `H_(2)` S

Answer

### Step-by-Step Solution:

1. **Understanding Haber’s Process**:
- The Haber process is a method for synthesizing ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂) gases. The balanced chemical equation for this reaction is:
\[ N_2(g) + 3H_2(g) \rightarrow 2NH_3(g) \]

2. **Identifying the Catalyst**:
- In the Haber process, a catalyst is used to accelerate the reaction without being consumed. The catalyst employed is finely divided iron (Fe).

3. **Role of Catalytic Poison**:
- A catalytic poison is a substance that decreases the activity of a catalyst. In the context of the Haber process, if a catalytic poison is present, it can hinder the efficiency of the iron catalyst, thus reducing the rate of ammonia synthesis.

4. **Identifying the Catalytic Poison**:
- In this process, hydrogen sulfide (H₂S) is known to act as a catalytic poison for the iron catalyst. When H₂S is present, it can bind to the active sites of the iron catalyst, reducing its effectiveness.

5. **Conclusion**:
- Therefore, the substance that acts as a catalytic poison in the Haber process is hydrogen sulfide (H₂S).

### Final Answer:
The substance that acts as a catalytic poison in Haber’s process of ammonia synthesis is **H₂S (hydrogen sulfide)**.

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