 : I see your point, there is a difference between solubility and solubility product. However, they are closely related What purpose is served by listing an arbitrary selection of Ksp values? The table would make more sense if it was part of a section in which quantitative values were discussed. For example, there could be an interesting discussion of comparative solubilities of hydroxides. I don't have a source on which to base it. Just giving the numbers doesn't really tell one anything. BTW, I've re-instated the link to the NIST database which had also been lost at some point.