For reaction `aA rarr xP`, when `[A] = 2.2 mM`, the rate was found to be `2.4mM s^(-1)`. On reducing concentration of `A` to half, the rate changes to `0.6 mM s^(-1)`. The order of reaction with respect to `A` is

Options

A. 1.5
B. 2
C. 2.5
D. 3

Answer

B

Explanation

Let rate, `r = k [A]^(n)`
In 1st case, `2.4 =k(2.2)^(n)`
In 2nd case, `[A]=2.2//2 = 1.1mM`
`0.6 = k(1.1)^(n)`
`:. (2.4)/(0.6) =(2)^(n)`
`4 = 2^(n)`
or `n=2`
`:.` Ratem `r=k [A]^(2)`
Hence, order = 2