00:01
To calculate the ph of the solution, we need to take the negative log of the hydronium ion concentration.
00:08
The hydronium ion concentration can typically be calculated by taking the square root of the concentration of the weak acid.
00:16
They tell us that we have 0 .034 molar coating hydrochloride, that being the concentration of the weak acid, multiplied by its ka value.
00:28
We don't know the ka value, but we do know the pkb for codeine hydrochloride.
00:32
It's base.
00:35
So if we take kw and we divide it by kb, kb being equal to 10 to the negative pkb.
00:51
So we've got kb, which is 10 to the negative pkb, divided into kw gets us ka.
01:01
We then take k, we then take ka, multiply it by the concentration of the weak acid, and so square root it and we get the hydronium concentration.
01:11
We then take the negative log of the hydrogenium concentration to get our ph.
01:15
And we get a ph of 4 .83.
01:22
For the next problem, to calculate the p -o -h, p -o -h is typically equal to 14 minus ph, and ph is going to be the negative log of the hydronium ion concentration, similar to what we did up here.
01:43
And the hydronium ion concentration is going to be the concentration of the weak acid, 0 .0950, multiplied by its k -a value, provided at 2 .55 times 10 to the negative 4.
02:07
And we get a p .o .h of 11 .69...