Page 1 of 1

### Unique Rate

Posted: Sat Mar 03, 2018 12:13 pm
Can someone clarify what unique rate laws are? I did not understand what Lavelle said during class about this. Thanks!

### Re: Unique Rate

Posted: Sat Mar 03, 2018 12:49 pm
The unique rate is the instantaneous rate of change at any time t during the reaction. Unlike the average rate, which takes into account all of the times at which the reaction proceeds and averages it, the instantaneous rate is specific to a time and therefore it generates a different k value. The general equation used for the unique rate can be written as rate=d[R]/dt while the average rate is rate=âˆ†concentration/âˆ†t. Unique rate laws are specific to each reaction and are confined to a specific time.

### Re: Unique Rate

Posted: Sat Mar 03, 2018 1:37 pm
In addition, when you calculate the unique rate, it is the same for all the reactants and products involved in the reaction.

### Re: Unique Rate  [ENDORSED]

Posted: Sat Mar 03, 2018 2:37 pm
For a reaction aA + bB -> cC + dD, where the lowercase letters are the stoichiometric coefficients and the uppercase letters are chemical species, the unique rate law is
$-\frac{1}{a}\frac{d[A]}{dt} = -\frac{1}{b}\frac{d[B]}{dt} = \frac{1}{c}\frac{d[C]}{dt} = \frac{1}{d}\frac{d[D]}{dt}$

This rate law is unique to the reaction and the same for all reactants and products in this reaction.

### Re: Unique Rate

Posted: Thu Mar 15, 2018 8:14 pm
thanks!

### Re: Unique Rate

Posted: Sat Mar 17, 2018 1:09 am
Is there a way to know when exactly we should be using unique rate?