Question

Consider the reaction A+2B⇌C whose rate at 25 ∘C was measured using three different sets of initial concentrations as listed in the following table: Trial [A] (M) [B] (M) Rate (M/s) 1 0.30 0.030 3.2×10−3 2 0.30 0.060 6.5×10−3 3 0.60 0.030 1.3×10−2 What is the rate law for this reaction? PART B aswell ?

Answer 1

The given reaction is    A+2B⇌C

Let the rate law be rate, r = k[A]^m[B]ⁿ    -------(1)

Where

k = rate constant , m = order of the reaction with respect to A , n = order of the reaction with respect to B

Let us apply the rate law to the given set of values in the tabular form.

1st values -----> 3.2x10^-3 = k[0.30]^m [0.030]ⁿ    ------(2)

1st values -----> 6.5x10^-3 = k[0.30]^m [0.060]ⁿ    ------(3)

1st values -----> 1.3x10^-2 = k[0.60]^m [0.030]ⁿ    ------(4)

(4) / (2) gives      4 = 2^m

                        2² = 2^m

                         m = 2

(3) / (2) gives      2 = 2ⁿ

                        2¹ = 2ⁿ

                         n = 1

Therefore the rate law be r = k[A]²[B]¹