THE PH IN GRAPH

We describe stick diagrams, which are simple graphs designed to provid e quick insight into complicated ionic equilibria. Despite their inher ent crudeness, they can be used to obtain numerical solutions to quant itative equilibrium problems. Moreover, they show when those quantitat ive answers are likely to be too approximate. Finally, we discuss how to make activity corrections, and conclude that activity corrections a re often as large or larger than the errors involved in using stick di agrams. Therefore, in the absence of activity corrections, stick diagr ams are usually quite adequate.