CAIE A-Level Chemistry A2 26.1.1 And Use the Terms Rate Equation Order Topic Practice

A four-step mechanism is suggested for the reaction between hydrogen peroxide and iodide ions in an acidic solution.

step 1 $\mathrm{H}_{2} \mathrm{O}_{2}+\mathrm{I}^{-} \rightarrow \mathrm{IO}^{-}+\mathrm{H}_{2} \mathrm{O}$

step 2 $\mathrm{H}^{+}+\mathrm{IO}^{-} \rightarrow \mathrm{HIO}$

step 3 $\mathrm{HIO}+\mathrm{I}^{-} \rightarrow \mathrm{I}_{2}+\mathrm{OH}^{-}$

step 4 $\mathrm{OH}^{-}+\mathrm{H}^{+} \rightarrow \mathrm{H}_{2} \mathrm{O}$

Step 1 is the rate-determining step.

State what is meant by the term rate-determining step.