## Reaction rate

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

Cecilia Jardon 1I
Posts: 74
Joined: Fri Sep 28, 2018 12:16 am

### Reaction rate

S2O8 ^-2 + 3I- --> 2SO4^2- + I3-
Rate of consumption of S2O8^2- = k [S2O8^2-] [I-]
The book says that doubling either the S2O8 ^2- ion concentration or the I- ion concentration doubles the reaction rate. I am confused as to what exactly the reaction rate is. Is it k? or is it the whole reaction: Rate of consumption of S2O8^2- = k [S2O8^2-] [I-]? Can someone help ? Thanks.

Steven Garcia 1H
Posts: 79
Joined: Fri Sep 28, 2018 12:16 am

### Re: Reaction rate

Hi!

k is just the rate constant, whereas the whole expression represents the rate of the reaction.

Another way to think about it is that the problem mentions the rate doubles as a result of doubling the concentration. Rate constants for a given reaction are CONSTANT, they do not change for a given reaction. Therefore, k can not be represent the reaction rate!