The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data.

H2O2 + I - = H2O + IO - (slow)
H2O2 + IO - = H2O + O2 + I - (fast)

Which one of the following statements is false? Choose answer (E) if more than one or none are false.

a. The reaction is first order with respect to H2O2.
b. The reaction is first order with respect to I -
c. I - is a catalyst.
d. IO - is an intermediate.
e. More than one the above statements is false (or none of the statements are false).

help

To determine which statement is false, we need to analyze the proposed mechanism and understand the order with respect to each species and the role of each species in the reaction.

The first step is the slow step, where hydrogen peroxide (H2O2) reacts with iodide ion (I-) to form water (H2O) and iodate ion (IO-).

The second step is the fast step, where hydrogen peroxide (H2O2) reacts with iodate ion (IO-) to form water (H2O), oxygen gas (O2), and iodide ion (I-).

Let's analyze each statement and whether it is true or false:

a. The reaction is first order with respect to H2O2.
- This statement is true. From the mechanism, we can see that H2O2 is involved in both the slow and fast steps, but it is not present in the rate-determining step (slow step). Therefore, the reaction is first order with respect to H2O2.

b. The reaction is first order with respect to I-.
- This statement is false. From the mechanism, we can see that I- is involved in the slow step but not in the rate-determining step (fast step). Therefore, the reaction is not first order with respect to I-.

c. I- is a catalyst.
- This statement is false. A catalyst is a substance that speeds up a reaction by providing an alternative reaction pathway and being regenerated at the end of the reaction. In the proposed mechanism, I- is directly involved in the reaction and consumed in the slow step. Therefore, I- is not a catalyst.

d. IO- is an intermediate.
- This statement is true. An intermediate is a species that is formed in one step of the reaction and consumed in a subsequent step. From the mechanism, we can see that IO- is formed in the slow step and consumed in the fast step. Therefore, IO- is an intermediate.

e. More than one of the above statements is false (or none of the statements are false).
- This statement is false. We have determined that statement c is false, but the rest of the statements are either true or false. Therefore, only one statement (c) is false.

So, the correct answer is: c. I- is a catalyst.