Experimental Determination of Ultraviolet Radiation Protection of Common Materials
Susana C. A. Tavares and Joaquim C. G. Esteves da Silva
CIQ(UP), Department of Chemistry, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal
João Paiva
Department of Chemistry, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal
Aiming at a better understanding of the problems associated with the depletion of the ozone layer, we propose several experiments to be performed by students of different levels: secondary and first-year undergraduate students. The oxidation of iodide induced by ultraviolet (UV) radiation, generated by a mercury lamp, is used as an indicator for the degree of exposure to UV radiation. Experiments were used to investigate UV radiation protection given by (i) a simulation of the ozone layer thickness using plexiglass plates; (ii) the use of sunscreen lotions; (iii) cotton cloth with different colors; and (iv) aqueous solutions with different concentrations of natural organic matter. These laboratory experiments and an impact study done with students were encouraging because their motivation for the study of chemistry increased and suggest that this innovative experimental strategy provides a relevant and up-to-date example of experimental chemistry.
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