Q.

The reaction 2NO+Br22NOBr

takes place through the mechanism given below:

NO+Br2NOBr2  (fast)

NOBr2+NO2NOBr  (slow)

The overall order of the reaction is ________ .               [2023]


Ans.

(3)

2NO+Br22NOBr

(i) NO+Br2k2k1NOBr2    Fast

(ii) NOBr2+NOk3slow2NOBr     r=k3[NOBr2][NO]        ...(i)

Keq=k1k2=[NOBr2][NO][Br2]    [NOBr2]=k1×[NO][Br2]k2

Now put [NOBr2] in equation (i) we get,

r=k1k3k2[NO]2[Br2]      r=k[NO]2[Br2]

So, overall order of reaction =2+1=3.