Picked up some HCl on the way home at lowes. Doing a ghetto tub purification tonight.Will try HCl titration later and report results. Meanwhile want to make sure i understand the HCl titration chemistry:
Starting solution has VG/PG and Nicotine salt, which is nicotine combined with benzoic or acetic acid. Potentially there is also free nicotine or free acid. I believe my salt is based on benzoic acid.
When I add HCl what i actually get are:
3. H+ and Cl-
The equilibria at play are:
1. Nic-Benzoic vs free nic+ and free benzoic- (this will go all the way to the right, b/c free benzoic- keeps getting protonated in 2.)
2. free benzoic- vs protonated benzoic (this will go towards protonated b/c its a weak acid and H+ is abundant from 3)
3. HCl vs H+ and Cl- this will go all the way to the right since HCl is strong acid
4. Nic-Cl vs free nic+ and free Cl- This will go all the way to the left due to abundance of Cl-
During titration, pH will fall and the titration point with steepest slope is when all benzoic acid has been protonated, hence giving me amount of benzoic acid present.
Does this sound about right?
Also, what should i expect to see in the event if solution has excess of nicotine or excess of benzoic. Isn't pH equivalence point basically giving me concentration of benzoic acid, so nicotine concentration is only determined by assumption that it is equal to concentration of benzoic acid?
On second thought, any benzoic acid not bound to nic is already protonated, since it is a weak acid, so titration would measure amount of benzoic bound to nic. But this still leaves the question of excess free nic preset.