Recebido em 18/9/00; aceito em 16/11/00 POLYPHOSPHATES IN COMMERCIAL POWDER DETERGENTS. A didactic experiment is proposed in order to identify inorganic phosphates in home laundry detergents by ascending paper chromatography. Chemical principles related with hard water are also investigated. The role of polyphosphates in detergent formulations is discussed and the softening of hard water by sodium tripolyphosphate is illustrated. Several chemical concepts, related to the daily experience of the students, can be explored in post-lab discussions.

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We describe the use of a chapter excerpt from Primo Levi's book The Periodic Table in two courses for first-year undergraduate students offered by the Institute of Chemistry of the University of São Paulo. The aim is to motivate the students by giving them a problem-solving activity based on a literary text.

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