Question

The rate of A + B → P is 3.6 × 10⁻² mol/dm³/s. When [A] = 0.2 M and [B] = 0.1 M. Calculate the rate constant if reaction is first order in B and second order in A.

Answer 1

Given:

For the reaction:

A + B → P

Rate = 3.6 × 10⁻² mol/dm³/s

[A] = 0.2 M

[B] = 0.1 M

Order in A = 2

Order in B = 1

Rate law expression:

Rate = k [A]² [B]¹

Substituting the values:

3.6 × 10⁻² = k × (0.2)² × (0.1)¹

3.6 × 10⁻² = k (0.04 × 0.1)

3.6 × 10⁻² = k (0.004)

k = `(3.6 xx 10^-2)/0.004`

k = 9 mol⁻² dm⁶ s⁻¹