For A_2+B_2 leftharpoons 2 AB E_a for forward and backward reaction are 180 and 200 ~kJ ~mol^-1 respectively If catalyst lowers E_a for both reaction by 100 ~kJ ~mol^-1 . Which of the following statement is correct?

Correct answer: (A) Catalyst does not alter the Gibbs energy change of a reaction.. A_2+B_2 leftharpoons 2 AB E_f=180 ~kJ ~mol^-1 E_b=200 ~kJ ~mol^-1 Δ H=E_f-E_b=-20 ~kJ ~mol^-1 In presence of catalyst : E_f=180-100=80 ~kJ ~mol^-1 E_b=200-100=100 ~kJ ~mol^-1 Catalyst does not change Δ H or Δ G of a reaction.

Q8 / 75 · JEE Main 2025 (4 Apr Shift 1) · Chemistry

For $\mathrm{A}_2+\mathrm{B}_2 \rightleftharpoons 2 \mathrm{AB}$
$\mathrm{E}_{\mathrm{a}}$ for forward and backward reaction are 180 and $200 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively
If catalyst lowers $\mathrm{E}_{\mathrm{a}}$ for both reaction by $100 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
Which of the following statement is correct?

Correct answer
A
Catalyst does not alter the Gibbs energy change of a reaction.
B
Catalyst can cause non-spontaneous reactions to occur.
C
The enthalpy change for the reaction is $+20 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
D
The enthalpy change for the catalysed reaction is different from that of uncatalysed reaction.

Solution

$\mathrm{A}_2+\mathrm{B}_2 \rightleftharpoons 2 \mathrm{AB}$
$\mathrm{E}_{\mathrm{f}}=180 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$\mathrm{E}_{\mathrm{b}}=200 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$\Delta \mathrm{H}=\mathrm{E}_{\mathrm{f}}-\mathrm{E}_{\mathrm{b}}=-20 \mathrm{~kJ} \mathrm{~mol}^{-1}$
In presence of catalyst :
$\begin{aligned}<br />& \mathrm{E}_{\mathrm{f}}=180-100=80 \mathrm{~kJ} \mathrm{~mol}^{-1} \\<br>& \mathrm{E}_{\mathrm{b}}=200-100=100 \mathrm{~kJ} \mathrm{~mol}^{-1}<br />\end{aligned}$
Catalyst does not change $\Delta \mathrm{H}$ or $\Delta \mathrm{G}$ of a reaction.

Hence, the correct answer is option: 'A'.

Solution

Relevant Questions