A2+B2⇌2AB
Ef=180 kJ mol−1
Eb=200 kJ mol−1
ΔH=Ef−Eb=−20 kJ mol−1
In presence of catalyst :
$\begin{aligned}
& \mathrm{E}_{\mathrm{f}}=180-100=80 \mathrm{kJ} \mathrm{mol}^{-1} \
& \mathrm{E}_{\mathrm{b}}=200-100=100 \mathrm{kJ} \mathrm{mol}^{-1}
\end{aligned}$
Catalyst does not change ΔH or ΔG of a reaction.