The decomposition of hydrogen peroxide in the presence of potassium iodide is believed to occur by the following mechanism:
step 1 slow: H2O2 + I^- = H2O + OI^-
step 2 fast: H2O2 + OI^- = H2O + O2 + I^-
1) What is the equation for the overall reaction? Use the smallest integer coefficients possible.
I am not sure about this part.
2) Which species acts as a catalyst? Enter formula if there is one.
I think that I^- is the catalyst.
3) Which species acts as a reaction intermediate?
I think the H2O2 is the reaction intermediate.
4) Complete the rate law fot the overall reaction that is consistent with this mechanism.
I know that it would be k[][] but I am not sure what it is.
Thank you for your help!!
1) To determine the overall reaction, you need to cancel out the common species on both sides of the mechanism. Combining step 1 and step 2, you can cancel out the I^-, H2O, and H2O2 species:
2H2O2 + 2I^- -> 2H2O + O2 + I^-
So, the overall reaction is:
2H2O2 + 2I^- -> 2H2O + O2 + I^-
2) A catalyst is a species that is involved in the reaction but is not consumed in the overall reaction. In this case, the I^- ion is not consumed in the overall reaction and is involved in both steps of the mechanism. Therefore, I^- acts as a catalyst.
3) A reaction intermediate is a species that is formed in one step and consumed in a subsequent step, but it does not appear in the overall reaction. In this mechanism, the H2O2 is formed in step 1 and consumed in step 2, but it is not present in the overall reaction. Therefore, H2O2 acts as a reaction intermediate.
4) To determine the rate law for the overall reaction, you need to consider the slow step of the mechanism. In this case, step 1 is the slow step. The rate-determining step is typically the slowest step in a reaction mechanism, and it dictates the rate law.
From step 1, you can see that the rate of the reaction is proportional to the concentration of H2O2 and I^-:
rate = k[H2O2][I^-]
So, the rate law for the overall reaction, consistent with this mechanism, is:
rate = k[H2O2][I^-]