Question

If the rate law for a reaction is rate = k[A]2[B]

a. What is the overall order of the reaction?

b. If the concentration of A is doubled and the concentration of B is tripled, how will this affect the rate of the reaction?

c. How will doubling the concentration of B while holding A constant affect the value of k (assuming that temperature remains constant)?

Answer 1

Concepts and reason

Rate law of a reaction:

Rate law gives the relationship between a reactant’s concentration and the reaction rate.

Order of a reaction:

The order of a reaction is defined as the sum of an exponent in the rate expression of a reaction concentration in terms of rate law equation.

Rate constant :

The proportionality constant that expresses the relationship between the rate of the reaction and the concentration of the reactants present in the reaction.

Fundamentals

Rate of reaction: It represents the change in the concentration of the reactants (consumed) or the change in the concentration of the product (formed) in a unit of time. Rate law can be expressed as follows:

(a)

Consider the given rate law,

(b)

Consider the given rate law,

If the concentration of is doubled and the concentration of is tripled, then the rate law becomes as follows,

Rate of reaction is increased by 12 times.

(c)

Consider the given rate law,

If the concentration of is constant and the concentration of is doubled, then the rate law becomes as follows,

Rate of the reaction is doubled but the rate constant remains constant.

Ans: Part a

The overall order of the reaction is 3

Part b

If the concentration of is doubled and the concentration of is tripled.

The rate of the reaction will be increased by 12.

Part c

Rate constant of the reaction remains constant