Product in Rate Law

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

Ying Yan 1F
Posts: 101
Joined: Fri Aug 02, 2019 12:16 am

Product in Rate Law

Usually, when we write out rate laws, we take only the reactants into consideration,
i.e. for the reaction H2 + I2 <=> 2HI, the rate law= k[H2][I2]

However, I know there are times that products are written into the rate law too, with a negative order,so my question is: when do we include products when writing rate laws? Thank you in advance!

405268063
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

Re: Product in Rate Law

I think HI in this case is a solid, and we don't include solids or liquids in the rate law expressions. As far as I know, I believe that if a product is gaseous or aqueous, we would include those.

Noe BM 1J
Posts: 50
Joined: Sat Sep 07, 2019 12:17 am

Re: Product in Rate Law

I think you only use the concentration of the reactants when calculating the rate (this is for differential rate laws).