# Question about reaction rate.

#### pfaction

##### Full Member
10+ Year Member
TBR 9.4:

What is the reaction order for the following one step reaction:

2 NO2 -> 2NO + O2

So obviously it's going to be rate = k[NO]^2 is second order.

But what about the rate itself? Would it be, -1/2[NO]^2 = (1/2)[NO^2] = [O]?

#### chiddler

##### Full Member
10+ Year Member

which means that you do not consider order in this way of writing the rate equation. only depends on stoichiometric coefficient.

#### pfaction

##### Full Member
10+ Year Member
Really, because there was a question on TPR's exams and I derived this directly from there.
2A -> 2B + C

= -1/2[A] = (1/2) + [C]

It's also heavy during TBR Ch 9 Gen Chem.

Last edited:

#### chiddler

##### Full Member
10+ Year Member
I don't see how that contradicts the equation I posted.

Can you please explain? I'm not seeing it.

#### SaintJude

##### Full Member
Yeah, pfaction, it's saying the same things as chiddler is saying.

#### MedPR

##### Membership Revoked
Removed
I concur.

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