A two-step reaction proceeds through the following energy levels

CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics

Problem

A two-step reaction proceeds through the following energy levels, all relative to the reactants R: • Intermediate I:

+10\,\text{kJ mol}^{-1}

• Product P:

-40\,\text{kJ mol}^{-1}

• Transition state TS

_1

(R → I):

+90\,\text{kJ mol}^{-1}

• Transition state TS

_2

(I → P):

+60\,\text{kJ mol}^{-1}

What is the activation energy for the reverse of the second step (P → I)? (a)

70\,\text{kJ mol}^{-1}

(b)

150\,\text{kJ mol}^{-1}

(c)

100\,\text{kJ mol}^{-1}

(d)

50\,\text{kJ mol}^{-1}