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JEE Main 20254 AprilMorning Shift
Exam
JEE Main
Year
2025
Date
4 April
Shift
Morning Shift
Subject
Chemistry
Chapter
Chemical Kinetics

JEE Main 2025 · 4 April · Morning Shift · Chemistry · Chemical Kinetics

For A_2+B_2 leftharpoons 2 AB E_ a for forward and backward...

For A2+B2⇌2AB\mathrm{A}_2+\mathrm{B}_2 \rightleftharpoons 2 \mathrm{AB}
Ea\mathrm{E}_{\mathrm{a}} for forward and backward reaction are 180 and 200 kJ mol−1200 \mathrm{~kJ} \mathrm{~mol}^{-1} respectively
If catalyst lowers Ea\mathrm{E}_{\mathrm{a}} for both reaction by 100 kJ mol−1100 \mathrm{~kJ} \mathrm{~mol}^{-1}.
Which of the following statement is correct?

Options

  1. ACatalyst does not alter the Gibbs energy change of a reaction.
  2. BCatalyst can cause non-spontaneous reactions to occur.
  3. CThe enthalpy change for the reaction is +20 kJ mol−1+20 \mathrm{~kJ} \mathrm{~mol}^{-1}.
  4. DThe enthalpy change for the catalysed reaction is different from that of uncatalysed reaction.

Correct answer

A. Catalyst does not alter the Gibbs energy change of a reaction.

Step-by-step solution

A2+B2⇌2AB\mathrm{A}_2+\mathrm{B}_2 \rightleftharpoons 2 \mathrm{AB}
Ef=180 kJ mol−1\mathrm{E}_{\mathrm{f}}=180 \mathrm{~kJ} \mathrm{~mol}^{-1}
Eb=200 kJ mol−1\mathrm{E}_{\mathrm{b}}=200 \mathrm{~kJ} \mathrm{~mol}^{-1}
Δ\Delta\mathrm{H}=\mathrm{E}f−Eb=−20 kJ mol−1_{\mathrm{f}}-\mathrm{E}_{\mathrm{b}}=-20 \mathrm{~kJ} \mathrm{~mol}^{-1}
In presence of catalyst :
<br/>Ef=180−100=80 kJ mol−1<br>Eb=200−100=100 kJ mol−1<br/>\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 ΔH\Delta \mathrm{H} or ΔG\Delta \mathrm{G} of a reaction.
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