Question

The following results have been obtained during the kinetic studies of the reaction:

2A + B → C + D

Experiment	A/ mol L−1	B/ mol L−1	Initial rate of formation of D/mol L−1 min−1
I	0.1	0.1	6.0 × 10−3
II	0.3	0.2	7.2 × 10−2
III	0.3	0.4	2.88 × 10−1
IV	0.4	0.1	2.40 × 10−2

Determine the rate law and the rate constant for the reaction.

Answer 1

Let the order of the reaction with respect to A be x and with respect to B be y.

Therefore, rate of the reaction is given by,

According to the question,

Dividing equation (iv) by (i), we obtain

Dividing equation (iii) by (ii), we obtain

Therefore, the rate law is

Rate = k [A] [B]²

From experiment I, we obtain

= 6.0 L² mol⁻² min⁻¹

From experiment II, we obtain

= 6.0 L² mol⁻² min⁻¹

From experiment III, we obtain

= 6.0 L² mol⁻² min⁻¹

From experiment IV, we obtain

= 6.0 L² mol⁻² min⁻¹

Therefore, rate constant, k = 6.0 L² mol⁻² min⁻¹