[问答题]
Concentrated aqueous hydrogen peroxide $(H_2O_2)$ decomposes when heated in the presence of iodide ions.
$2H_2O_2(aq)$→$2H_2O(l)$+$O_2(g)$
1.Suggest how the rate of the reaction could be measured.
2.The proposed mechanism for the reaction involves two steps.
Step1:
$H_2O_2(aq)$+$I^{-}(aq)$→$H_2O(l)$+$IO^{-}(aq)$
Step 2:
$H_2O_2(aq)$+$IO^{-}(aq)$→$H_2O(l)$+$I^{-}(aq)$+$O_2(g)$
The energy level diagram for this mechanism is shown.
1.Explaining your reasoning, use the energy level diagram to deduce the rate-determining step (RDS).
2.Estimate the activation energy for the reaction, $kJ$ $mol^{-1}$.
$E_a$:_______________$kJ$$mol^{-1}$
3.The reaction rate is measured at different reactant concentrations. Explain how this experiment could be used to prove or disprove the proposed reaction mechanism.
3.The reaction can also be catalyzed by the enzyme catalase. The activation energy for this reaction, $E_a$, is 21.3 $kJ$$mol^{-1}$and the frequency factor, A, is$41\times 10^{10}$$mol^{-1}dm^{3}s^{-1}$.Calculate the value of the rate constant at $20^{\circ}C$, in units of $mol^{-1}dm^{3}s^{-1}$. Use sections 1 and 2 of the data booklet.
$\kappa$=_____________$mol^{-1}dm^{3}s^{-1}$
