The decomposition of in aqueous solution has the experimentally determined rate law (…

CHEMISTRY · Single correct · AP · Chemistry · Kinetics · Kinetics

Problem

The decomposition of

\mathrm{H_2O_2}

in aqueous solution has the experimentally determined rate law

\text{rate}=k[\mathrm{H_2O_2}][\mathrm{I^-}]

, where

\mathrm{I^-}

acts as a catalyst. Spectroscopic analysis shows that the concentration of

\mathrm{I^-}

at the beginning and end of the reaction is the same within experimental error. Which of the following best explains this observation? (a)

\mathrm{I^{-}}

is consumed in the slow elementary step and regenerated in a subsequent step, so there is no net change in its concentration. (b)

\mathrm{I^{-}}

is present in such a large excess that the small amount consumed is negligible. (c)

\mathrm{I^{-}}

is inert and does not actually participate in the reaction mechanism. (d)

\mathrm{I^{-}}

is produced by the decomposition of

\mathrm{H_2O_2}

at the same rate that it is consumed, keeping its concentration constant.