JEE Main · 2019 · 08 Apr 2019 · Shift 1 · Chemical Kinetics

For the reaction

2 A + B \to C

, the values of initial rate at different reactant concentrations are given in the table below: The rate law for the reaction is:

Answer: (B)

Solution

Write the rate as

k [A]^{x} [B]^{y}

and read the orders from the runs. Between the first two, where

[B]

is fixed and

[A]

doubles, the rate doubles, so

2 = 2^{x}

and

x = 1

. From the second run to the third,

[A]

doubles and

[B]

doubles while the rate rises eightfold, so

8 = 2^{1} \times 2^{y}

, giving

2^{y} = 4

and

y = 2

. The rate law is

Rate = k [A] [B]^{2}

JEE Main · 2019 · 08 Apr 2019 · Shift 1 · Single correct option