A computational study has generated relative potential-energy values (in kJ mol⁻¹) for five points along the reaction coordinate of the elementary transformation
G(g) → H(g)
The data are referenced to the energy of the reactants.
Point
Position along coordinate
Energy (kJ mol⁻¹)
1
Reactants
0
2
25 % of pathway
+40
3
50 % of pathway
+115
4
75 % of pathway
+60
5
Products
–20
Assume the reaction proceeds via a single transition state.
(a) Using the tabulated points, plot an approximate reaction energy profile on appropriately labeled axes. Draw a smooth curve that passes near the provided energies and include a clearly indicated transition state.
(b) From your graph or by appropriate interpolation, estimate the activation energy for the forward reaction and the activation energy for the reverse reaction.
(c) Determine the overall energy change, ΔE, and state whether the reaction is thermodynamically favorable under standard conditions.
(d) Assess whether the data are internally consistent with the assumption that the reaction proceeds through a single transition state. In your discussion, comment on any features of the plotted curve that support or challenge this assumption.