The rate constant of a reaction of zero order in A is 3 × 10 - 3 mol L - 1 s - 1 . How long will it take for the initial concentration of A to fall from 0 . 10 M to 0 . 075 M ?

Rate constant in a zero order can be calculated as : k = R ∘ - R t , where R ∘ is initial molar concentration of reactant and k is rate constant of the zero order reaction. t = R ∘ - R k t = 0 . 1 - 0 . 075 3 × 10 - 3 = 8 . 3 s Hence, the value of time comes out to be 8 . 3 s

Find the molecularity of the reaction, Cl → 1 2 Cl 2 ( g ) . Give the potential energy diagram to explain activation energy.

Molecularity is defined as the number of reactants taking part in a chemical reaction. For the given reaction, Cl → 1 2 Cl 2 ( g ) , molecularity is one. Activation energy is required by reactants to form activated complexes and is equal to the difference between threshold energy and average kinetic energy. This can be explained by the following graph :

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.