Question

The reaction S(s) + O2_2​2​​(g) → SO2_2​2​​(g) has Ea_a​a​​ = 150 kJ/mol at a certain temperature. Given that ∆Hf_f​f​​∘°(SO2_2​2​​(g)) = -296.1 kJ/mol, determine the activation energy (in kJ/mol) of the reverse reaction at the same temperature.

Answer 1

Solution:- From given information, the reaction is exothermic as the delat H value is negative. Activation energy, Ea for the forward reaction is 150 kJ/mol. Activation energy for the forward reaction is the difference of energy between reactants and activated complex. Delta H is the energy difference between products and reactants.

For the backward reaction, the energy difference between products(reactants for the backward reaction) and activated complex.

So, Ea for backward reaction = Ea of forward reaction + delta H

Ea for backward reaction = 150 kJ/mol + 296.1kJ/mol = 446.1 kJ/mol

If we consider sig figs then it would be 446 kJ/mol.