## Orders for Reactions

$\frac{d[R]}{dt}=-k[R]^{2}; \frac{1}{[R]}=kt + \frac{1}{[R]_{0}}; t_{\frac{1}{2}}=\frac{1}{k[R]_{0}}$

Maggie Miller 2K
Posts: 11
Joined: Fri Jun 17, 2016 11:28 am

### Orders for Reactions

When reviewing the notes, it seems that the order of reactions in some cases (like elementary steps for overall reactions) can be found just with the coefficients. However, in other cases (I do not know which), you cannot consider the coefficients to be the order for the reactants.

In which scenarios can each concept be applied?

Thanks!

Natalie Rotstein 3J
Posts: 20
Joined: Wed Sep 21, 2016 2:59 pm

### Re: Orders for Reactions

In the textbook, it is said that "the rate law for a reaction is determined experimentally and cannot in general be inferred from the chemical equation for the reaction." I think that in general, the order might look like it can be "found" with the coefficients, but in reality the order just happens to correspond with the numbers in that situation while in other situations it doesn't.

Alyssa_Hsu_2K
Posts: 55
Joined: Wed Sep 21, 2016 3:00 pm

### Re: Orders for Reactions

You can only find the order of reactions from coefficients if it's an elementary reaction.
If you were given the overall reaction, you cannot find its order from its coefficient.