Resumo

CARRASQUENO, Armando; GONZALEZ, Arnoldo; FLORES, Iraima  e  NAVAS, Petra Beatriz. Determinación de la constante de estabilidad (KE) del ión triyoduro como  una practica de laboratorio a micro escala. Paradìgma [online]. 2007, vol.28, n.1, pp.203-214. ISSN 1011-2251.

This paper proposes a laboratory activity for the course of analytical chemistry, that involves the determination of the equilibrium constant of I₃^- formation (Ke) through the partition of iodine between an organic solvent and an aqueous solution of potassium iodide. The quantification of I₂ and I₃^- are made by visible spectrophotometric measurements, which implies a reduction in the amounts of reactive needed and are less time consuming. The students outline the chemical and mathematical models, make measurements, build graphics and analyze the results to obtain a Ke value. Results are similar to those obtained by the traditional laboratory activity. Also a protocol for the treatment of residues is incorporated to purify the solvent and for the  neutralization of aqueous solution  to reduce the environmental impact. En general speaking it can be said that the proposed activity have several advantages in the saving of resources and time.   

Palavras-chave : micro scale; stability constant; triiodide; laboratory; teaching; chemistry.