# Rxn Mechanisms and Rate Laws

aprilrenee

## Homework Statement

The reaction S2O82- + 3 I-1 -> 2 SO42- + I3-1 is first order in both reactants. The following mechanism is proposed:

I-1 + S2O82- -> IS2O83-
IS2O83- -> 2 SO42- + I+
I+ + I-1 -> I2
I2 +I-1 -> I3-1

a) Which step is the rate determining step?
b) Show that this mechanism is stoichiometrically equal to the overall equation.
c) Why would you expect the slow step in part (a) to be the slow step?
d) Why would you expect the third step to be the fastest step?

## Homework Equations

1) How do I determine if a step is slow or fast?
2) In part (b), when it asks to show that the mechanism is stoichiometrically equal to the overall equation, does that mean adding up the steps? If so, I don't get it because wouldn't I then just add up all the other steps anyway? Or, do I balance the equation to make it look like the overall equation?

## The Attempt at a Solution

Correct me if I'm wrong, but is the rate for this reaction:
Rate = k[S2O82-][I-1]

Other than that, I've been trying to google and YouTube many things to assist me.. I've received no luck. Any help would be appreciated!