Which equilibrium in gaseous phase would be unaffected by an inerease in pressure ?

Options

A. `N_(2) O_(4(g)) hArr 2NO_(2(g))`
B. `N_(2(g)) + O_(2(g)) hArr 2NO_((g))`
C. `N_(2(g)) + 3H_(2(g)) hArr 2 NH_(3(g))`
D. `CO_((g)) + (1)/(2) O_(2(g)) hArr CO_(2(g)) `

Answer

To determine which equilibrium in the gaseous phase would be unaffected by an increase in pressure, we need to analyze the relationship between the number of moles of reactants and products in a chemical equilibrium.

### Step-by-Step Solution:

1. **Understanding Le Chatelier's Principle**:
- According to Le Chatelier's Principle, if a system at equilibrium is subjected to a change in pressure, the equilibrium will shift to counteract that change. This typically means that if the pressure increases, the equilibrium will shift towards the side with fewer moles of gas.

2. **Identifying Moles of Reactants and Products**:
- For a gaseous equilibrium to be unaffected by an increase in pressure, the number of moles of gaseous reactants must equal the number of moles of gaseous products. This is because if the moles are equal, a change in pressure will not favor either side of the reaction.

3. **Analyzing Given Equilibria**:
- We will analyze the number of moles on both sides of the equilibrium for different reactions.
- For example:
- Reaction 1: A(g) ⇌ 2B(g) → 1 mole of A and 2 moles of B (Total = 3 moles)
- Reaction 2: 2C(g) ⇌ 2D(g) → 2 moles of C and 2 moles of D (Total = 4 moles)
- Reaction 3: D(g) ⇌ E(g) + F(g) → 1 mole of D and 2 moles (Total = 3 moles)
- Reaction 4: 1.5G(g) ⇌ H(g) → 1.5 moles of G and 1 mole of H (Total = 2.5 moles)
- Reaction 5: 2I(g) ⇌ 2J(g) → 2 moles of I and 2 moles of J (Total = 4 moles)

4. **Finding the Right Equilibrium**:
- From the analysis, we find that the only case where the number of moles of reactants equals the number of moles of products is in the second case (2C(g) ⇌ 2D(g)). Here, both sides have 2 moles.

5. **Conclusion**:
- Therefore, the equilibrium that would be unaffected by an increase in pressure is the one where the number of moles of reactants equals the number of moles of products. In this case, option B is the correct answer.