Chemistry Everyday for Everyone edited by
Cost-Effective Teacher
Harold H. Harris University of Missouri—St. Louis St. Louis, MO 63121
Using Plastiline in the Laboratory Francisco J. Arnáiz Laboratorio de Química Inorgánica, Universidad de Burgos, 09001 Burgos, Spain
With regard to the ingenious Boyle’s law experiment recently proposed (1), I wish to point out that clay can be advantageously replaced by plastiline. It works satisfactorily, is handled more easily than clay (residual portions are completely removed without depositing contamination), is resistant to water (whereas clay forms suspensions), and retains its properties for a long time without the necessity of protection against loss of volatiles (unprotected clay dehydrates rapidly and may crack). This observation should also be read as an invitation for a more widespread use of this material in chemistry laboratories. Parallelepiped blocks of plastiline are readily available at low cost and in several colors and can serve a variety of purposes. I use those of dimensions 10 × 5 × 2 cm as supports for small, round-bottomed flasks and vials in the microscale laboratory because holes of custom size can be reversible and tailored. I also use it for the soft-sealing of tubes, preparing seals crossed by several tubes and connecting a variety of glassware pieces, including funnels to flasks (for systems that operate at a pressure close to ambient).
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It is also very useful for students to use plastiline spheroids for the visualization of coordination polyhedra, the close packing of spheres, the number and relative sizes of tetrahedral and octahedral holes, and simple ionic models. One can prepare, in a short time, thirty or so spheroids of approximately 1.5 cm diameter, sufficiently consistent in size for these purposes, and adherent and reluctant to roll across the bench. Literature Cited 1. Lewis, D. L. J. Chem. Educ. 1997, 74, 209. Note from the Feature Editor For those who (like me) are not familiar with plastiline, it is an artist’s material that is widely used for sculpture. It can be purchased at art supply houses in most communities, or by mail. Current prices are approximately $1.50 to $2.50 per pound in small quantities, and it is available in at least eight colors. It has essentially no hazardous properties. HH
Journal of Chemical Education • Vol. 75 No. 11 November 1998 • JChemEd.chem.wisc.edu
