Consider the elementary reaction {A(g) + B(g)} {C(g) + D(g)} If the volume of reaction mixture is suddenly reduced to 13 of its initial volume, the reaction rate will become 'x' times of the original reaction rate. The value of x is:

9. Step 1 — Rate law for elementary reaction: R_1 = k[{A}][{B}] = k{n_A}{V}{n_B}{V} Step 2 — Volume reduced to 13V, so concentrations become 3×: R_2 = k{3n_A}{V}{3n_B}{V} = 9R_1 Answer: (b) x = 9

JEE Main · 2025 · Shift-IIeasyCK-143

Consider the elementary reaction {A(g) + B(g)} {C(g) + D(g)} If the volume of reaction mixture is suddenly reduced to…

Chemical Kinetics · Class 12 · JEE Main Previous Year Question

Question

Consider the elementary reaction

$\text{A(g) + B(g)} \rightarrow \text{C(g) + D(g)}$

If the volume of reaction mixture is suddenly reduced to $\tfrac{1}{3}$ of its initial volume, the reaction rate will become ' $x$ ' times of the original reaction rate. The value of $x$ is:

Options

a
$\tfrac{1}{9}$
b
$9$
✓
c
$\tfrac{1}{3}$
d
$3$

Correct Answerb

$9$

Detailed Solution

Step 1 — Rate law for elementary reaction:

$R_1 = k[\text{A}][\text{B}] = k\cdot\tfrac{n_A}{V}\cdot\tfrac{n_B}{V}$

Step 2 — Volume reduced to $\tfrac{1}{3}V$ , so concentrations become 3×:

$R_2 = k\cdot\tfrac{3n_A}{V}\cdot\tfrac{3n_B}{V} = 9R_1$

Answer: (b) $x = 9$

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