A reaction is first order in `A` secod order in `B`:
(i) write differential rate equation.
(ii) How is the rate affected when the concentration of `B` is tripled ?
(iii) How is the rate affected when the concentration of both `A` and `B` is doubled?

Explanation

(i) The differential rate equation will be
`-(d [R])/("dt") = k [A] [B]^(2)`
(ii) If the concentration of B is increased three times , then
`-(d[R])/("dt") = k[A] [3B]^(2)`
= `9* k [ A] [B]^(2)`
Therefore , the rate of reaction will increase 9 times
(iii) When the concentrations of both A and B are doubled ,
`-(d [R])/("dt") = k[A] [B]^(2)`
= `k[2A][2B]^(2)`
= `8*k [A][B]^(2)`
Therefore , the rate of reaction will increase 8 times .