NEET2026ChemistryChapterActual
The potential energy diagram for a reversible chemical reaction R P is shown in the figure. Based on the provided profile, which of the following options correctly gives the activation energy for the backward reaction ( E_ a(bwd) ) and the enthalpy change ( H ) for the forward reaction?
Options
- AE_ a(bwd) = 50 kJ mol ⁻¹ , H = +35 kJ mol ⁻¹
- BE_ a(bwd) = 85 kJ mol ⁻¹ , H = +35 kJ mol ⁻¹
- CE_ a(bwd) = 85 kJ mol ⁻¹ , H = -35 kJ mol ⁻¹
- DE_ a(bwd) = 105 kJ mol ⁻¹ , H = -35 kJ mol ⁻¹
Correct answer
C. E_ a(bwd) = 85 kJ mol ⁻¹ , H = -35 kJ mol ⁻¹
Step-by-step solution
From the given potential energy diagram: Energy of reactants, E_R = 55 kJ mol ⁻¹ Energy of products, E_P = 20 kJ mol ⁻¹ Energy of transition state, E_ TS = 105 kJ mol ⁻¹ The activation energy for the backward reaction is: E_ a(bwd) = E_ TS - E_P E_ a(bwd) = 105 - 20 = 85 kJ mol ⁻¹ The enthalpy change for the forward reaction is: H = E_P - E_R H = 20 - 55 = -35 kJ mol ⁻¹ Answer: E_ a(bwd) = 85 kJ mol ⁻¹ , H = -35 kJ mol ⁻¹