Exercise 1 | Chemical Kinetics: Mechanisms

For a reaction, the value of ΔHrxn = -20 kJ.mol-1 and the value of the activation energy is 40 kJ.mol-1.

What is the energy of the activation energy in the reverse direction?

Ea (forward reaction) = Ea (reverse reaction) +  ΔHrxn

⇒ Ea (reverse reaction) = Ea (forward reaction) - ΔHrxn = 40 + 20 = 60 kJ.mol-1