if you start with 100ml alkaloids and dissolve them in the mineral oil like you said, then re-extract to acid at 5.6...
remove the acidified water, basify and then extract back to fresh non polar, measure how much you get back. If it's >90ml, then we will know for certain that the single protonation site is creates enough of a preference for the acid phase.
There might still be issues with using the weaker organic acids, multiple kpa's etc... but it's one less easter egg.![]()
Let's not sell weak organic acids short.
5% acetic acid isn't too shabby with a pKa of 4.76.
We can get the Ka easily enough as pKa = -log(Ka) or 4.76 = -log(Ka) or Ka = 0.0000174.
so [H+][CH3COO-] / [CH3COO3] = 0.0000174 and at 5% or 0.833N, we have [H+][CH3COO-]/[0.833] = 0.0000174. So [H+] = 0.003807.
And pH is simply -log(0.003807) or 2.42. (with one lazy shortcut that has little effect).
Citric acid is even stronger.
pKa1=3.09 (Ka=0.0008)
pKa2=4.75
pKa3=6.41
so 0.25 molar citric acid gives [H+][Citrate-] / undissociated = 0.0008 so [H+] = 0.014M or pH=1.85
and that's not even counting the added acidity of the weaker hydrogens.
So putting around 50g of citric acid into a liter of water gives a pH < 1.85
Not too shabby at all.
