In `NH_3` synthesis by Haber's process, what is the effect on the rate of the reaction with the addition of Mo and CO, respectively?

Options

A. Increases and decreases
B. Decreases and decreases
C. Decreases and increases
D. Both Mo and Co increases the rate

Answer

To solve the question regarding the effect of Mo (Molybdenum) and CO (Carbon Monoxide) on the rate of NH3 synthesis in the Haber process, we can break it down into the following steps:

### Step 1: Understand the Haber 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:
\[ N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \]
This reaction typically requires a catalyst to proceed at a reasonable rate.

### Step 2: Identify the Role of Catalysts
Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. In the case of the Haber process, various catalysts can be used to enhance the reaction rate.

### Step 3: Analyze the Effect of Mo (Molybdenum)
When Molybdenum (Mo) is used as a catalyst in the Haber process, it has been observed to increase the rate of ammonia formation. This is because Mo facilitates the breaking of the N≡N triple bond in nitrogen, allowing for a more efficient reaction with hydrogen.

### Step 4: Analyze the Effect of CO (Carbon Monoxide)
On the other hand, when Carbon Monoxide (CO) is introduced into the reaction as a catalyst, it decreases the rate of ammonia formation. CO can act as a poison to the catalyst, inhibiting the reaction by blocking active sites on the catalyst surface, thus slowing down the overall reaction.

### Step 5: Conclusion
From the analysis, we conclude:
- The addition of Mo increases the rate of NH3 formation.
- The addition of CO decreases the rate of NH3 formation.

Therefore, the correct answer to the question is that Mo increases the rate while CO decreases the rate of the reaction.

### Final Answer
The addition of Mo increases the rate of NH3 formation, while the addition of CO decreases the rate of NH3 formation.

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