Exercise 7C Question 5

[Vivian Leung 1C]

Hi,

Could someone please explain part b of this question (see attachment)?

How do we know that the rate law is

Step 1: k [HBr] [NO2]
Step 2: k [HBr] [HBrO]

without knowing the order of the reactants?

[Savana Maxfield 3F]

Hi! I believe because part b is just asking for the rate law of each elementary step, the rate law will just be based off of the coefficients of the reactants (in this case 1).

[Sedge Greenlee]

As Savana said the order will be based on the coefficients of the elementary steps. The molecularity is just the sum of said orders for each elementary step.

[Vivian Leung 1C]

That makes sense. Thank you!