Under what conditions of temperature and pressure the formation of atomic hydrogen from molecular hydrogen will be favoured most ?

Options

A. High temperature and high pressure
B. Low temperature and low pressure
C. High temperature and low pressure
D. Low temperature and high pressure

Answer

To determine the conditions of temperature and pressure under which the formation of atomic hydrogen from molecular hydrogen is favored, we can apply the principles of chemical equilibrium, particularly Le Chatelier's principle. Here's a step-by-step solution:

### Step 1: Understand the Reaction
The dissociation of molecular hydrogen (H₂) into atomic hydrogen (H) can be represented as:
\[ \text{H}_2(g) \rightleftharpoons 2\text{H}(g) \]
This reaction is endothermic, meaning it absorbs heat.

### Step 2: Identify the Nature of the Reaction
Since the reaction is endothermic, we know that:
- The forward reaction (dissociation of H₂) requires heat.
- According to Le Chatelier's principle, if we increase the temperature, the equilibrium will shift to favor the endothermic reaction.

### Step 3: Analyze the Effect of Temperature
To favor the formation of atomic hydrogen, we should increase the temperature. This is because:
- Higher temperatures provide the necessary energy to overcome the bond energy of H₂, thus promoting the dissociation into atomic hydrogen.

### Step 4: Analyze the Effect of Pressure
Next, we consider the effect of pressure. The reaction involves:
- 1 mole of H₂ gas producing 2 moles of H gas.
- According to Le Chatelier's principle, if we increase the pressure, the equilibrium will shift towards the side with fewer moles of gas.

In this case, since we are producing more moles of gas (2 moles of H from 1 mole of H₂), we need to lower the pressure to favor the dissociation of H₂ into atomic hydrogen.

### Step 5: Conclusion
Based on the analysis:
- **High Temperature**: To favor the endothermic reaction.
- **Low Pressure**: To favor the production of more moles of gas.

Thus, the conditions under which the formation of atomic hydrogen from molecular hydrogen is favored are **high temperature and low pressure**.

### Final Answer
**High Temperature and Low Pressure**

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