A reaction is of second order in A and first order in B

cbse
chemical-kinetics

#1

A reaction is of second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentration of both A and B is doubled?


#2

A reaction is second order in A and first order in B.
(i) Differential rate equation
Rate = -d[R] / dt = k [${{A}^{2}}$] [B]
(ii) When the concentration of A is increased three times, i.e. 3 A, then
Rate = k [${{3A}^{2}}$] [B]
= 9k [${{A}^{2}}$] [B] = 9 (rate)
This shows that rate will increase 9 times to the initial rate.
(iii) When concentration of both A and B is doubled
Rate = k [ ${{2A}^{2}}$] [2B] = 8k [${{A}^{2}}$] [B] = 8 (rate)
This shows that rate will increase 8 times to the initial rate.