# How do we assess the solubilities of various salts in various solutions?

${K}_{s p}$ values are usually tabulated for a variety of sparingly soluble and insoluble salts. Of course, this relies on initial measurments (usually by the use of radioisotopes).
You still have to be able to use the ${K}_{s p}$ values in a variety of situations. $P b C {l}_{2}$ should be more soluble in pure water than in hydrochloric acid. Why should this be so?