JEE Main · 2025 · 28 Jan 2025 · Shift 2 · Chemical Kinetics

consider the elementary reaction

A (g) + B (g) \to C (g) + D (g)

If the volume of reaction mixture is suddenly reduced to

\frac{1}{3}

of its initial volume, the reaction rate will become '

x

' times of the original reaction rate. The value of x is :

Answer: (B)

Solution

For the elementary reaction

A (g) + B (g) \to C (g) + D (g)

, the rate law follows directly from stoichiometry:

r a t e = k [A] [B]

. Concentration is moles per unit volume, so shrinking the volume to

V /3

triples every concentration:

[A]^{'} = 3 [A]

and

[B]^{'} = 3 [B]

. The new rate is

k (3 [A]) (3 [B]) = 9 k [A] [B]

, nine times the original.

x = 9

JEE Main · 2025 · 28 Jan 2025 · Shift 2 · Single correct option