A Lab Experience To Illustrate the Physicochemical Principles of Detergency
J. A. Poce-Fatou
Departamento de Química Física, Universidad de Cádiz, Facultad de Ciencias, Polígono del Río San Pedro, 11510 Puerto Real, Cádiz, Spain
M. Bethencourt-Núñez
Departamento de Ciencias de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Universidad de Cádiz, Facultad de Ciencias del Mar y Ambientales, Polígono del Río San Pedro, 11510 Puerto Real, Cádiz, Spain
C. Moreno and J. J. Pinto-Ganfornina
Departamento Química Analítica, Universidad de Cádiz, Facultad de Ciencias del Mar y Ambientales, Poligono del Río San Pedro, 11510 Puerto Real, Cádiz, Spain
F. J. Moreno-Dorado
Departamento Química Orgánica, Universidad de Cádiz, Facultad de Ciencias, Polígono del Río San Pedro, 11510 Puerto Real, Cádiz, Spain
This article presents a lab experience to study detergency from a physicochemical point of view intended for undergraduate students. By means of a simple experimental device, we analyze the influence of the surfactant concentration in both distilled water and tap water. Our method is based on the measurement of diffuse reflectances of polyester samples impregnated with linseed oil. The discussion of the experimental results helps to introduce physicochemical concepts such as surfactant, adsorption, surface tension, work of adhesion, Gibbs isotherm, and electrical double layer, emulsion, or micelle. The device and the methodology adapt easily to study the influence of other experimental parameters such as temperature, stirring intensity, washing time, type of surfactant, and so forth. To extend the range of applicability of this experience we have included, in the Supplemental Material, detailed information about the syntheses of the organic and inorganic components of the detergent, analytical techniques to measure water hardness, surface tension measurements, and the mathematical treatment of experimental errors.
Supplement
Detailed information about the syntheses of the organic and inorganic components of the detergent, analytical techniques to measure water hardness, surface tension measurements, and the mathematical treatment of experimental errors are available.
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.
