00:02
There, in this question, we are told that the ph is 11 .9.
00:06
And the first thing we want to do is find the hydroxide ion concentration.
00:11
Well, to do that, the first thing i want to know is what the poh is.
00:14
And we're told there in the question that ph plus poh add up to 14.
00:24
Therefore, since the ph is 11 .9, the poh is going to be 14 minus 11 .9.
00:34
Or in other words, the poh is going to be 2 .1.
00:40
Okay, so from that, we need to find the hydroxide ion concentration.
00:46
Well, there's another equation that is not given up to us here, but it tells us that the hydroxide ion concentration is going to be the inverse log or antilog of the negative poh.
01:03
And this just comes from the equation that tells us poh is the negative log of the hydroxide ion concentration.
01:12
So rewriting that equation, we get this.
01:15
So let's go ahead and calculate that oh-.
01:18
We need to take the anti -log, or your calculator may just call it the inverse log, of negative, the poh is 2 .1.
01:30
Okay, so we type in negative 2 .1.
01:32
We take the inverse log or anti -log of that, and we'll get our oh - concentration.
01:40
That oh - concentration is 7 .94 times 10 to the negative third.
01:53
This is the concentration, so it is molarity...