If we prepare hydrochloride salt of a base, what are the factors determining solubility of the salt over a pH range of 1-12 assuming the pKa is 9.0? Under what circumstances we can anticipate precipitation? Does common ion effect play a role?
Common bases in the form of hydroxide don't have their hydrochloride salts, I think. This better fits for amines, though. Note that pKa of 9.0 belongs to the amine, when converted to its hydrochloride, it will be about 2-6.9. Precipitation may be encountered when the overall concentration is too high for water, especially containing any common ions, you are right. The salt will not be dissolved well in alcohol as it may be in aqueous solution. So, changing the type of solvent may anticipate precipitation.