For a general reactions
` 2A +B hArr C +3D , Delta H = + x kcal `
What will be the effect of
decrease in volume ?

Answer

To solve the problem, we will analyze the effect of a decrease in volume on the given reaction using Le Chatelier's Principle.

### Step-by-Step Solution:

1. **Identify the Reaction and Moles:**
The given reaction is:
\[ 2A + B \rightleftharpoons C + 3D \]
- On the reactant side, we have:
- 2 moles of A
- 1 mole of B
- Total = 2 + 1 = 3 moles
- On the product side, we have:
- 1 mole of C
- 3 moles of D
- Total = 1 + 3 = 4 moles

2. **Understand the Effect of Volume Change:**
According to Le Chatelier's Principle, if a system at equilibrium is subjected to a change in conditions (such as volume), the system will adjust itself to counteract that change.

3. **Analyze the Decrease in Volume:**
- When the volume is decreased, the pressure of the system increases.
- The system will respond by shifting the equilibrium position towards the side with fewer moles of gas to reduce the pressure.

4. **Determine the Direction of Shift:**
- In our reaction:
- Reactants: 3 moles (2A + 1B)
- Products: 4 moles (1C + 3D)
- Since there are fewer moles of gas on the reactant side (3 moles) compared to the product side (4 moles), the reaction will shift towards the side with fewer moles when the volume is decreased.

5. **Conclusion:**
- Therefore, when the volume is decreased, the equilibrium will shift to the left (towards the reactants) because it has fewer moles of gas.

### Final Answer:
The effect of a decrease in volume on the reaction \(2A + B \rightleftharpoons C + 3D\) will be that the equilibrium shifts towards the reactants (left side) due to the presence of fewer moles of gas on that side.

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