00:01
So we have these two second order reactions, and the integrated rate law for a second order reaction is where we need to start because we need to relate the amounts at different times.
00:16
We're given the initial concentration, and we want the concentration of a 2 after three minutes.
00:33
I just realized that i've done this, calculated the concentration of a, but it'll be simple enough to calculate the concentration of a2.
00:42
So let's go on.
00:44
So we're going to calculate the concentration of a after three minutes, and that is kt.
00:50
So the k was given for the reaction of a after three minutes.
00:54
Notice that the k is given, the rate constant, is given as per molar per second.
01:04
Or the inverse of molar per second.
01:06
But our time is given in minutes, so we need to rationalize that with conversion to the seconds.
01:14
Plus 1 over a 0, the initial concentration was 1 times 10 to the minus 2.
01:20
And so these first three factors combine to give 45 per molar and 1 over 1 times 10 to minus 2 is 100.
01:31
So 1 over a, 1 over the concentration at 3 minutes is 45.
01:37
So the concentration at 3 minutes is 1 over 145.
01:44
So here's our concentration of a after 3 minutes.
01:47
So how much a was used up? so that was the change in concentration of a.
02:15
Well, what would be the concentration change for a2? that will be the concentration of a2.
02:23
At 3 minutes.
02:25
Well, that would be molar, change in concentration, decrease in concentration of a, and then 2 moles a for each, sorry, nope.
02:47
We want the, we want the a in the denominator, and so that's 1 mole a2 for each 2 moles of a.
03:06
And so the, the, uh, and so the, uh, answer for a2 at 3 minutes would be 0 .015.
03:20
That's the concentration of a2 at 3 minutes.
03:26
We calculated that from the change in concentration of a...