00:01
To determine the rate law, we need to determine the order of the reaction with respect to each reactant.
00:07
If we look at experiments 1 and 3, we see that only the concentration of b is changing.
00:17
The concentrations of a and c are constant.
00:21
The concentration of b increases 1 .5 times.
00:28
When this occurs, there is no change to the rate.
00:32
So with the change in concentration of b and no change to the rate, this indicates that it is zero order with respect to b.
00:43
Now if we look at experiments 1 and 2, we see that there is a change in the concentration of b, but we can ignore that because we know it's zero order with respect to b, and that won't affect the rate.
00:58
But additionally, there is a doubling of the concentration of a.
01:04
Goes from 0 .2 to 0 .4 molar.
01:07
When this happens we end up getting a quadrupling of the rate.
01:11
It goes to 9 .6 times 10 to the negative 6 molar per minute from 2 .4 times 10 to the negative 6 molar per minute.
01:21
So if we double the concentration and we end up quadrupling the rate, what do we need to raise the change in concentration to to get the 4? that would be two.
01:33
So that means it's second order with respect to a...