A + 2 B → 3 C + 2 D . The rate of disappearance of B is 0 . 5 × 10 - 3 mol L - 1 s - 1 . What will be the rate of the reaction?

Given : d B dt = 0 . 5 × 10 - 3 mol L - 1 s - 1 . For the reaction, A + 2 B → 3 C + 2 D , rate can be expressed as : Rate = - d A dt = - 1 2 d B dt = + 1 3 d C dt = + 1 2 d D dt . Hence, rate of reaction = 1 2 d B dt = 1 2 × 0 . 5 × 10 - 3 mol L - 1 s - 1 = 0 . 25 × 10 - 3 mol L - 1 s - 1 .

A + 2 B → 3 C + 2 D . The rate of disappearance of B is 0 . 5 × 10 - 3 mol L - 1 s - 1 . What will be rate of change in concentration of A and B ?

Given : d B dt = 0 . 5 × 10 - 3 mol L - 1 s - 1 . For the reaction, A + 2 B → 3 C + 2 D , rate can be expressed as : Rate = - d A dt = - 1 2 d B dt = + 1 3 d C dt = + 1 2 d D dt . Rate of change in concentration of : A = d A dt = 1 2 d B dt = 1 2 × 0 . 5 × 10 - 3 mol L - 1 s - 1 = 0 . 25 × 10 - 3 mol L - 1 s - 1 The rate of change in concentration of B is already given 0 . 5 × 10 - 3 mol L - 1 s - 1 .

Under what condition a bimolecular reaction behaves kinetically first order reaction?

In a bimolecular reaction, when the amount of one of the reactants is present in excess, the reaction is kinetically first order because the concentration of reactant present in excess does not affect the order of reaction. Hence, it does not affect the rate of reaction and such reactions are called pseudo first order reactions. Example : Hydrolysis of sucrose yielding glucose and fructose.