00:01
So in this question, we're going to be asked to calculate ph of solutions.
00:05
The first one is a hydroxide, which is a base, and the second one is an acid.
00:10
And they're both strong, which helps us.
00:14
So the first one is b -a -o -h -2, which is one of the strong bases.
00:19
What's nice about a strong base, like barium hydroxide, is that it completely associates.
00:25
So you have barium and then hydroxide.
00:31
What we have to remember is that because it's 2 .8 times 10th the negative 4th molar, it's still 2 .8 times 10 to negative 4th molar barium, but it's twice that of hydroxide because of the way it dissociates.
00:48
It's 2 to 1, 2 to 1 ratio.
00:54
So because it's a hydroxide, we can't calculate ph directly.
00:58
We have to calculate p .o .h first.
01:00
So p .o .h equals the negative log of the concentration of the oh minus.
01:06
So this is equal to the negative log of 5 .6 times 10 to the negative fourth, which gives us a p .o .h of 3 .25.
01:21
Now, any substance has both a ph and a p .o .h...