Iron (II) ion is oxidized by hydrogen peroxide in acidic solution.
H2O2(aq) + 2Fe2+(aq) + 2H+(aq) ---> 2Fe3+(aq) + 2H2O (l)
the rate law is k[H2O2][Fe2+]
what is the order with respect to each reactant ? what is the overall order
To determine the order with respect to each reactant and the overall order of the reaction, you need to examine how the rate of the reaction changes with changing concentrations of the reactants.
The rate law of the reaction, given as k[H2O2][Fe2+], indicates that the reaction rate is directly proportional to the concentrations of both hydrogen peroxide ([H2O2]) and iron (II) ion ([Fe2+]).
To find the order with respect to hydrogen peroxide, you can perform a series of experiments and compare the reaction rates while keeping the concentration of iron (II) constant and varying the concentration of hydrogen peroxide. Let's say you perform two experiments:
Experiment 1: [H2O2]1
Experiment 2: [H2O2]2
If you observe that the rate of the reaction doubles when the concentration of hydrogen peroxide is doubled ([H2O2]2 = 2[H2O2]1), then the reaction is first order with respect to hydrogen peroxide ([H2O2]).
Similarly, to find the order with respect to iron (II) ion, you can perform another set of experiments while keeping the concentration of hydrogen peroxide constant and varying the concentration of iron (II) ion. Let's say you perform two experiments:
Experiment 3: [Fe2+]1
Experiment 4: [Fe2+]2
If you observe that the rate of the reaction quadruples when the concentration of iron (II) ion is doubled ([Fe2+]2 = 2[Fe2+]1), then the reaction is second order with respect to iron (II) ion ([Fe2+]).
Since the rate law is given by k[H2O2][Fe2+], where the exponents on the concentrations are 1 and 2, respectively, you can sum them to find the overall order of the reaction.
Overall order = 1 + 2 = 3
Therefore, the order with respect to hydrogen peroxide is 1, the order with respect to iron (II) ion is 2, and the overall order of the reaction is 3.