Question

The reaction between SO2 and O2 to give SO3 was studied to determine the rate law for the reaction. The following results were obtained The rate law is a) k[SO2][O2] b) k[SO2]2[O2] c) k[SO2]2 d) k[SO2][ O2]−2 e) k[SO2][ O2]−1

Answer 1

Answer : (b) The rate law expression for the reaction is:

$\text{Rate}=k[SO_2]^2[O_2]$

Explanation :

Rate law : It is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

The general reaction is:

$A+B\rightarrow C+D$

The general rate law expression for the reaction is:

$\text{Rate}=k[A]^a[B]^b$

where,

a = order with respect to A

b = order with respect to B

R = rate  law

k = rate constant

$[A]$ and $[B]$ = concentration of A and B reactant

Now we have to determine the rate law for the given reaction.

The balanced equations will be:

$2SO_2+O_2\rightarrow 2SO_3$

In this reaction, $SO_2$ and $O_2$ are the reactants.

The rate law expression for the reaction is:

$\text{Rate}=k[SO_2]^2[O_2]^1$

or,

$\text{Rate}=k[SO_2]^2[O_2]$