00:01
So we have to calculate the ph of a titration between hypochlorous acid and a base.
00:11
So a weak acid and a strong base.
00:14
Here's the equation of the reaction.
00:16
Hcl plus hclo plus hydroxide ion will give me chloride ion plus water.
00:22
Now in the first case, the number of moles of the acid is 0 .05 times multiplied by 0 .22 which is its concentration and what we have here is 0 .011 moles.
00:41
As for the strong base which has a concentration of 0 .22 also, we have 0 .03 when you have 30 mules times 0 .220 and what i have here is 0 .0066.
00:56
Quite obvious that the acid is in excess.
01:02
So minus 0 .0066 minus 0 .0066 and that would be the number of moles of the conjugate base of the acid form.
01:11
The acid is then in excess by 0 .0044 and of course the concentration of the hclo, the excess, is 0 .0044 divided by the total volume of the solution which is 80 mules now.
01:31
It's the 50 mules plus the 30 mules and this would give you 0 .055.
01:40
On the other hand, the concentration of the conjugate base is 0 .0066.
01:51
This is narrow.
01:53
This should be 0 .0066 divided by 0 .080 and this would give you 0 .0825.
02:07
And so the ph is the pka of hypochlorous acid is given to us as 7 .46.
02:21
So 7 .46 plus log of the base at 0 .0825 divided by the acid 0 .055 and this would give me 7 .6.
02:42
Interesting...