text: during extraction, why is it preferred to use hcl instead of h2so4 to acidify the aqueous layer? i'm trying to separate an organic base from a mixture. if i acidify the mixture solution, the base will be deprotonated and become soluble in water and go in to the aqueous layer.   ... ...   i think it has something to do with mono-protic and diprotic character, but i don't know exactly how that will affect the choid of the acid. help? chloride salts tend to make nicer crystals--easier to isolate and cleaner for melting point determinations.