00:01
In this reaction we're asked to consider the buffer that i've written right here.
00:05
And we're going to use the henderson -hasselbalch and we're going to calculate, i'm going to write this down here, the ratio of h2po4 and hpo4 components to yield ph of 1, ph of 6 .22, and 3, ph of 8 .2.
01:09
Okay, let's go up here and get started.
01:14
So the pka that i'm going to be interested in is, or the ka, i guess i'll go to my pka.
01:29
That's not what it equals, that's my ka.
01:50
I didn't want to write this here.
01:57
That's fine, i don't care.
02:03
So my pka will equal 10, will equal the negative log of 6 .3 times 10 to the minus 8, that'll equal 7 .20.
02:21
So that's my pka.
02:25
So next for this we're going to take 6 .22 equals 7 .20 plus the log of my base concentration over my acid concentration.
02:44
And i should have written this in.
02:45
This is my hpo4 2 minus, this is my h2po4 1 minus.
02:53
Okay, so this will equal, where's my calculator, 6 .22 minus 7 .2.
03:11
This is 0.
03:13
Negative 0 .98 equals the log of my substances here...