A reaction is first order in A and second order in B
i) Write differential rate equation.
ii) How is rate affected when the concentration of B is tripled?
iii) How is rate affected when the concentration of both A and B are doubled?

Explanation

i) Differential rate equation for the reactioin is : rate ( r)`= k[A]^(1)[B]^(2)`
ii) Differential rate equation for the reaction is: rate `(r^('))=k[A]^(1)[3B]^(2)`
`r^(')//r = (K[A]^(1)[3B]^(2))/(k[A]^(1)[B]^(2))` = 9 or `r^(') = 9r`
The reactioon rate will increase to 9 times.
iii) Differential rate equation for the reaction is:
rate `(r^('')) = k[2A]^(1)[2B]^(2), r^('')//r= (k[2A]^(1)[2B]^(2))/(k[A]^(1)[B]^(2)) =8 or r^(') = 8r`
The reaction rate will increase to 8 times.