Question

# A reaction is of second order with respect to a reactant. How is its rate affected if the concentration of the reactant is (i) doubled (ii) reduced to half?

Let the concentration of the reactant be [A] = a

Rate of reaction, R = k [A]2 = ka2

(i) If the concentration of the reactant is doubled, i.e. [A] = 2a, then the rate of the reaction would be

R = k (2a)2

= 4ka

= 4R

Therefore, the rate of the reaction would increase by 4 times.

(ii) If the concentration of the reactant is reduced to half, i.e., then the rate of the reaction would be

Therefore, the rate of the reaction would be reduced to