Question

For an elementary reaction 2A+B2→2AB, if the volume of the vessel is reduced to one-third of its original volume, then the rate of the reaction will:

a. increase by 27 times
b. decrease by 27 times
c. increasae by 32 times
d. decrease by 32 times

Answer 1

The rate of the reaction 2A + B2 \u2192 2AB will (a) increase by 27 times when the volume of the vessel is reduced to one-third, due to the proportional relationship between reactant concentrations and reaction rate for an elementary reaction.

Step-by-step explanation:

For the elementary reaction 2A + B2 \u2192 2AB, if the volume of the vessel is reduced to one-third, the concentrations of gases A and B2 will increase threefold given the inversely proportional relationship between volume and concentration (PV=nRT).

Since the rate of reaction depends on the frequency of the collisions, which is proportional to the product of the concentrations of the reactants, we must consider the impact of concentration changes on the reaction rate for this bimolecular reaction.

For an elementary reaction with stoichiometry 2A + B2, the rate law would be rate = k[A]^2[B2]. Thus, reducing the volume to one-third, thereby tripling the concentration of A and B2 ([A]' = 3[A] and [B2]' = 3[B2]), would affect the rate as follows:

rate' = k [A]'^2[B2]' = k (3[A])^2(3[B2]) = 27k[A]^2[B2]

This indicates the rate would increase by 27 times when the volume is reduced to one-third.