Floating Plastics: An Initial Chemistry Laboratory Experience
Enrique A. Hughes, Helena M. Ceretti, and Anita Zalts
Instituto de Ciencias, Área Química, Universidad Nacional de General Sarmiento, Roca 850, 1663 San Miguel, Prov. Bs. As., Argentina
Chemists routinely prepare a great variety of solutions. Sometimes it is necessary to confirm that the intended product was obtained. This may be done by measuring physical properties such as absorbance, electrical conductivity, melting point, boiling point, osmotic pressure, and density. This experiment is an initial experience for introductory chemistry courses, illustrating density by application in flotation-based techniques for identification and separation of plastics. Students prepare a series of solutions with gradually increasing densities. Then they are given plastic samples of known and unknown composition and they estimate the densities of the samples by observing in which solutions they float and in which they sink. These densities are used to identify the plastics. This experiment can be linked to discussions of recycling issues and industrial applications such as identification, classification, and separation of materials.
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Citation
Hughes, Enrique A.; Ceretti, Helena M.; Zalts, Anita. J. Chem. Educ.2001 78 522.
Keywords
Introductory / High School Chemistry; Laboratory Instruction; Nonmajor Courses; Plastics; Polymer Chemistry; Solutions / Solvents
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