Question

In a reversible reaction, the energy of activation of the forward reaction is 50 kcal. The energy of activation for the reverse reaction will be

• A. < 50 kcal
• B. 50 kcal
• C. either greater than or less than 50 kcal
• D. > 50 kcal

Answer 1

The Correct Option is C

 In a reversible reaction, the energy of activation (Ea) plays a crucial role in determining the rate of both the forward and reverse reactions. The problem given provides the energy of activation for the forward reaction, which is 50 kcal. Our task is to determine the energy of activation for the reverse reaction and explain why the correct answer is "either greater than or less than 50 kcal".

Let's break it down step-by-step:

1. The relationship between the activation energies of the forward and reverse reactions and the enthalpy change of the reaction (ΔH) is given by the equation:
2. \(E_{\text{reverse}} = E_{\text{forward}} + \Delta H\),
3. where \(E_{\text{forward}}\) is the activation energy of the forward reaction, and \(E_{\text{reverse}}\) is the activation energy of the reverse reaction, and. ΔH is the enthalpy change.
4. If a reaction is exothermic, ΔH is negative. This makes \(E_{\text{reverse}} > E_{\text{forward}}\).
5. If the reaction is endothermic, ΔH is positive. This makes \(E_{\text{reverse}} < E_{\text{forward}}\).
6. In this context, we are not provided the specific enthalpy change (ΔH), but we know the relationship. Hence, without additional information about the reaction being exothermic or endothermic, the energy of the reverse reaction could be either greater than or less than 50 kcal.

Thus, the given answer "either greater than or less than 50 kcal" is correct because it depends on whether the reaction is exothermic or endothermic, which is not specified. Therefore, without knowing ΔH, the energy of activation for the reverse reaction can vary.