00:01
For it to be a good buffer, we need to add a weak acid with its conjugate base, or we could have a weak acid and add a strong base in order to make the conjugate base.
00:23
As long as we don't add any more strong acid than we have weak acid, we will still have weak acid, and we would have made some of the conjugate base by adding a strong base and we'll have a buffer.
00:41
Another buffer solution could be a weak base to which we add a little bit of strong acid.
00:52
Because we're adding just a little bit of strong acid, then some of the weak base will be converted into a weak acid, and when that happens we'll have both a weak base and its conjugate acid, and we'll have a buffer solution.
01:10
So for the first one, if we have a solution that is prepared with equal volumes of 0 .50 molar hf, which is a weak acid, and 0 .50 molar sodium fluoride, the fluoride of sodium fluoride is the conjugate base to the weak acid, so we have a weak acid and its conjugate base.
01:37
This is a good buffer solution.
01:47
For the next one, we are preparing it by taking, actually this is two, we're taking 0 .50 molar hf and we're adding 0 .50 molar sodium hydroxide.
02:13
So here we have a weak acid with a strong base, but we're adding the same amount of strong base as we have weak acid, so we're converting all of the weak acid into its conjugate base fluoride...