The reaction X + X₃ → 2 X₂ is shown to have an activation energy of 25 kJ/mol while the enthalpy of reaction (∆H) is -388 kJ/mol. What is the activation energy of the reverse reaction?

Answer 1

It will take 388 kJ/mole to get back to the enthalpy of the reactants and an additional 25 kJ/mole to reach the activated intermediates. That would be a total of 413 kJ/ mole for the activation energy of the reverse reaction.