Question

The following mechanism has been proposed for the reaction of NO with `Br_(2)` to from NOBr.
`NO(g)+Br_(2)hArrNOBr_(2)(g)`
`NOBr_(2)(g)+NO(g)rarr2NOBr(g)`
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is
A. 1
B. 0
C. 3
D. 2

Answer 1

Correct Answer - d
The differential rate law for , NO + `Br_(2) to NOBr_(2)` would be
`-(dc)/(dt) = k[NOBr_(2)][NO]`
We have , `K_(c) = ([NOBr_(2)])/([NO][Br_(2)])`
Provided the first reaction attains equilibrium rapidly .
`therefore -(dc)/(dt) = k xx k_(c) xx [NO]^(2) [Br_(2)] = k[NO]^(2) [Br_(2)]`
`therefore` The order of the reaction with respect to NO(g) is 2 .