Question

The reaction between peroxide \(\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)\) and iodide in basic solution is proposed to occur according to the following mechanism:

Step \(1: \mathrm{H}_{2} \mathrm{O}_{2}+\mathrm{I}^{-} \rightarrow \mathrm{HOl}+\mathrm{OH}^{-}\) slow

Step \(2: \mathrm{OH}^{-}+\mathrm{H}^{+} \rightarrow \mathrm{H}_{2} \mathrm{O}\) fast

Step \(3: \mathrm{HOl}+\mathrm{H}^{+}+\mathrm{I}^{-} \rightarrow \mathrm{I}_{2}+\mathrm{H}_{2} \mathrm{O}\) fast

The rate law for this mechanism would be?

Select one:

O. Rate \(=\mathrm{k}\left[\mathrm{H}_{2} \mathrm{O}_{2}\right][\mathrm{I}]\left[\mathrm{OH}^{-}\right]\left[\mathrm{H}^{+}\right]\)

0. Rate \(=k\left[\mathrm{H}_{2} \mathrm{O}_{2}\right]\)

O C. Rate \(=k[\mathrm{OH}]\left[\mathrm{H}^{+}\right]\)

O d. Rate \(=k\)

O e. Rate \(=\mathrm{k}\left[\mathrm{H}_{2} \mathrm{O}_{2}\right][\mathrm{I}]\)

Answer 1

Rate law expression for a reaction is defined as

Rate law = k [reactant]^stochiometric coefficient

Where k is rate constant.

And in a multi step reaction rate determing step is used for rate law equation and rate determining step is the slowest step during the reaction

In the given problem 1st step is slowest hence it is rate determining step so rate law is

Rate = k[H2O2][I-]

So the correct option in e .