Question

The following mechanism has been proposed for this catalyzed reaction:

H₂O₂ + I^– → IO^– + H₂O

H₂O₂ + IO^– → I^– + H₂O + O₂

a) Write the formula for any intermediate.

b) Write the formula for any catalyst.

c) Show how the steps in the mechanism add to the decomposition of H₂O₂.

Answer 1

a)

intermediates are those which will not be consumed:

in this specific case:

IO–; since it goes in products on top and in the reactants in the bottom...

This is called an intermediate, since it is a byproduct which eventually is used again

b)

a catalyst is used to start a reaction, and it is NOT cosumed... therefore, from the list it is I-

since it appears in the reactants and it is produced in the final stage, i.e. regenerated

c)

Add all:

reactants:

H2O2 + I- + H2O2 + IO-

add products

IO- + H2O + I- + H2O + O2

add all

H2O2 + I- + H2O2 + IO- = IO- + 2H2O + I- + O2

cancel commo terms (intermediates + catalysts)

H2O2 + H2O2 = 2H2O + O2

add

2H2O2 = 2H2O + O2

this shows the decompoistion equation, total O = 4 in left 4 in right, total H = 4 left 4 in right side

this shows how H2O2 decomposes to water + oxygen gas