For the gas phase reaction `C_(2) H_(4) + H_(2) hArr C_(2) H_(6) (Delta H = - 32.7 K.cal )` carried out in a vessel, the equilibrium concentration of `C_(2)H_(4)` can be increased by

Options

A. increasing the temperature
B. Increasing the pressure
C. adding some `H_(2)`
D. removing some `C_(2)H_(6)`

Answer

To solve the problem of how to increase the equilibrium concentration of \( C_2H_4 \) in the reaction \( C_2H_4 + H_2 \rightleftharpoons C_2H_6 \) with a given enthalpy change of \( \Delta H = -32.7 \, \text{kcal} \), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Type of Reaction**:
The reaction given is exothermic because the enthalpy change (\( \Delta H \)) is negative. This means that heat is released when the reaction proceeds to the right (towards the formation of \( C_2H_6 \)).

2. **Apply Le Chatelier's Principle**:
According to Le Chatelier's principle, if a system at equilibrium is disturbed, the system will adjust itself to counteract the disturbance and restore a new equilibrium. For exothermic reactions, an increase in temperature shifts the equilibrium to the left (towards the reactants).

3. **Determine the Effect of Temperature**:
Since the reaction is exothermic, increasing the temperature will favor the reverse reaction, which is the formation of the reactants \( C_2H_4 \) and \( H_2 \). This means that the concentration of \( C_2H_4 \) will increase.

4. **Conclusion**:
To increase the equilibrium concentration of \( C_2H_4 \), the temperature should be increased.

### Final Answer:
The equilibrium concentration of \( C_2H_4 \) can be increased by **increasing the temperature**.

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