JOURNAL of the Tunisian Chemical Society

The calculation of pH is studied as an example of the determination of chemical concentrations in solution, which are involved in one or several equilibrium. With this type of problem, the essential difficulty is the necessity to approximate, using considerations of a chemical order, to simplify the mathematical problem. The aim of this article is to present, using the example of strong or weak acid solutions:

• the systematic method which allows one, in ail cases and without taking into account considerations of a chemical order, to reveal the most simple mathematical relationship that leads to an acceptable value for pH. The relative error not to be exceeded is fixed in advance.
• the treatment of this type of problem by computer, in order to obtain the most simple mathematical relationship that leads to an acceptable value of pH.

J.L. Janier Dubry

Pages 29-47