The energy of activation of a forward reaction is 50 kcal . The energy of activation of its backward reaction is

Options

A. equal to 50 kcal
B. greater then 50 kcal
C. less than 50 kcal
D. either greater or less than 50 kcal

Answer

To determine the energy of activation for the backward reaction when the energy of activation for the forward reaction is given as 50 kcal, we can use the following approach:

### Step-by-Step Solution:

1. **Understand Activation Energy**:
- The activation energy (Ea) is the minimum energy required for a chemical reaction to occur. For a forward reaction, this is the energy needed to convert reactants into products.

2. **Identify the Forward Reaction**:
- In this case, the activation energy for the forward reaction is given as 50 kcal.

3. **Consider the Backward Reaction**:
- The backward reaction is the reverse of the forward reaction. The activation energy for the backward reaction (Ea backward) can be determined by considering the difference in energy between the reactants and products.

4. **Energy Diagram**:
- Draw an energy diagram where the y-axis represents energy and the x-axis represents the reaction coordinate.
- Mark the energy level of the reactants and products. The activation energy for the forward reaction is the height of the energy barrier from the reactants to the top of the energy hill (transition state).

5. **Relate Forward and Backward Activation Energies**:
- The energy of activation for the backward reaction can be calculated using the formula:
\[ E_a (\text{backward}) = E_a (\text{forward}) + \Delta H \]
- Here, \(\Delta H\) is the change in enthalpy of the reaction, which is the difference in energy between products and reactants.

6. **Conclusion**:
- Without specific values for the enthalpy change (\(\Delta H\)), we cannot determine a precise value for the backward activation energy. It can be either greater than, less than, or equal to 50 kcal depending on whether the reaction is exothermic or endothermic.

### Final Answer:
- The energy of activation for the backward reaction can be greater than, less than, or equal to 50 kcal, depending on the enthalpy change of the reaction.