Question

H,000+ in the presence of aq) is proposed to be: (slow) (fast) The mechanism for the first-order reaction 2 H., (aq) → Step 1: H,93(aq) + 1"(aq) → H,00) + O1"(aq) Step 2: H,03(aq) +01"(aq) → H,0(1+0,6) + 1"(aq) Identify the catalyst in the reaction. a H20 b. c. H₂02 d. or 0.02

Answer 1

In order to answer questions like these, one must understand the role of a catalyst. A catalyst is the species that is added to a reaction system to speed up the kinetics of the reaction by providing an alternate pathway, one with lower activation energy as compared to the activation energy of the reaction where no catalyst is used. Also, a catalyst remains unconsumed in the process.

Now, in case of decomposition of hydrogen peroxide (H₂O₂) into water and oxygen, it is known that this reaction occurs spontaneously irrespective of whether a catalyst is added or not.

So, keeping this in mind and the aforementioned role of catalysts (see the first paragraph), one can easily tell just by looking at the reaction mechanism that iodide (I^-) is the catalyst used. Also, iodide ion is restored in the end as can be seen in the second step.

So, the correct choice is option b.