Question

A reaction is of second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is reduced to half ?What is the unit of the rate constant for such a reaction ?

Answer 1

Let the reaction is A --> Product

Rate = k[A]2

(I) If conc. of A is doubled

R’ = K[2A]2 = 4K[A]2 = 4R

So rate of reaction will increae four times.

(ii) If conc, of reactants is reduced to half

R’ = K[1/2A]2= 1/4K[A]2= R/4

Rate of reaction will reduced to one fourth of the initial rate.

Answer 2

The specific rate constant (k) is the proportionality constant relating the rate of the reaction to the concentrations of reactants. The rate law and the specific rate constant for any chemical reaction must be determined experimentally. The value of the rate constant is temperature dependent.