## Difference between catalysts and intermediates

Arrhenius Equation: $\ln k = - \frac{E_{a}}{RT} + \ln A$

Mila 304269286
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Joined: Fri Sep 20, 2013 3:00 am

### Difference between catalysts and intermediates

I didn't quite understand the example done in class on Wednesday on pg 78 of our course reader. Why is NO a catalyst and not an intermediate but NO2 is an intermediate and not a catalyst?

-Mila 1H

Kim Vu 2G
Posts: 29
Joined: Fri Sep 25, 2015 3:00 am

### Re: Difference between catalysts and intermediates

NO2 is an intermediate because by definition, an intermediate is a substance that is produced in one step and then used up in another step of the reaction mechanism. NO2 here matches this definition as it is produced in the first step and then used up in the second step. NO however is a catalyst because it is added in the first and second step as it is not being produced from one step to another and since it is on the left side of step 1 and right side of step 2, it will be canceled out in the final reaction equation.