TEACHING ANALYTICAL CHEMISTRY AT THE MOLECULAR LEVEL

C.A. Rius-Alonso, A. Quere Thorent, Y. González-Quezada

Universidad Nacional Autónoma de Mexico (MEXICO)
Analytical chemistry of solution deals with reactions and equilibrium state of solutes in order to find appropriate conditions to characterize or quantify analytes. Chemical kinetics, study how fast reactants and product concentration are changing, whereas chemical equilibrium tells us, what those concentrations are once they have stopped changing.

The studies of equilibrium provide the information needed to affect the final concentrations of products by altering conditions. Le Chatelier´s principle is very important to explain the equilibrium, it states that the direction in which the system proceeds back to equilibrium is such that the change is partially offset until the equilibrium is reached. This principle has a significant implication in Analytical Chemistry.

During this part of the course, the relation between the structure and chemical equilibrium is discussed using Molecular Modeling programs. As reaction's changes greatly in their speed, they also varied in their extent. Fast reactions can give products in high yield or in a very low yield. The kinetic of a reaction is related to the speed, the concentration of product that is appearing per unit time. The equilibrium of a reaction applies to the extent of it, the concentration of product when no further change is observed.

One of the main objective of the course is to teach students the equilibrium state at the macroscopically and molecular levels, and then focus on the equilibrium constant and its relation to the balanced equation. At the Faculty of Chemistry (UNAM) we are using several Molecular Modeling programs as Spartan and Odyssey to teach students the molecular and macroscopic behavior of reaction.

This work was partially supported by a grant from Dirección General de Asuntos del Personal Académico (DGAPA) Universidad Nacional Autónoma de México PE205313.