Question

Consider the reaction 2A + 2B → 2C + D. From the following data, calculate the order and rate constant of the reaction.

[A]0/M	[B]0/M	r0/Ms-1
0.488	0.160	0.24
0.244	0.160	0.06
0.244	0.320	0.12

Write the rate law of the reaction.

Answer 1

Given : 

2A + 2B → 2C + D

If order of the reaction is x in A and y in B then, by rate law,

Hence the reaction is 2nd order in A.

If,

Hence the reaction is first order in B. 

The order of overall reaction = n = n_A + n_B 

= 2 + 1 = 3 

By rate law, 

Rate = R = k[A]²[B]

∴ (i) Order of reaction = 3 

(ii) Rate constant = k = 63M^-2s^-1

(iii) Rate law : Rate = k [A]²[B]