Question

What is the order with respect to each reactant and the overall order of the reaction? write the rate law. Also, calculate the rate constant for the reaction and the units of the rate constant.

What is the order with respect to each reactant and the overall order of the reaction? write the rate law. Also, calculate the rate constant for the reaction and the units of the rate constant.

Answer 1

From experiments 1 and 4, it is seen that [B] the concentration of B is the same but [A] has been made 4 times, the rate of the reaction has also become 4 times. Hence the order with respect to A is 1. i.e., rate ∝ [A],

From experiments 2 and 3, it may be noted that [A] is kept the same but [B] is doubled. The rate of reaction increases by 4 times, i.e., the order with respect to B is 2 combining both,
rate = k[A] [B]². This is the rate law for the reaction.

Alternatively, suppose the order with respect to A is α and the order with respect to B is β, the general rate law for the reaction is
rate = k [A]^α [B]^β

From the data given

Unit of rate constant (k)

Calculation of rate constant: Substitute the values of α and β in any of the equations.

Hence k = 6.0 mol^-1 L² min^-1.