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

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.