## 15.3 Rate Laws Depending on concentrations of products

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

Jessica Yang 1J
Posts: 55
Joined: Fri Sep 29, 2017 7:03 am

### 15.3 Rate Laws Depending on concentrations of products

Hi!

For Chapter 15 Section 3, on page 621, there is an example for the rate law for the decomposition of ozone. In the rate law, both the concentration of products and reactants matter. How do you know when the rate law depends on both the concentration of products and reactants, and not just the reactants?

Thanks!

Curtis Tam 1J
Posts: 105
Joined: Thu Jul 13, 2017 3:00 am

### Re: 15.3 Rate Laws Depending on concentrations of products

I believe its because the presence of O2 as a product can have a significant impact on the overall reaction rate. This was probably determined experimentally. I'm pretty sure if we are given a problem where we don't have much background info, we can just use reactants for the rate law :)

Wenxin Fan 1J
Posts: 53
Joined: Thu Jul 13, 2017 3:00 am

### Re: 15.3 Rate Laws Depending on concentrations of products

Use reactants when dealing with reaction rate problems for this class.

Janet Nguyen 2H
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am

### Re: 15.3 Rate Laws Depending on concentrations of products

In the homework, there were a couple problems on rate law and proposing mechanisms. Only one of them had an elementary step that had a significant reverse reaction, and it was given to you in the problem that that was the case, so I don't think you need to worry about it too much!