Brass: A Safer Version of an Old Favorite Pennies are coated with zinc by submerging in boiling NaOH containing a small swap of zinc powder, rinsed, and then heated to form brass. The version known as "Alchemy," originally described by Scott, Hill, and Muto ( I ) and appearing currently in Hassell, Gamer, and Hi11 ( 2 )has been a popular laboratory experience for our nanscienee majors for several years. The experiment was adapted from a demonstration of solid-state diffusion that appeared in this Journal (3). The version used in our laboratory is the culmination of efforts to address some safety concerns: the concentration of sodium hydroxide has been significantly reduced (from 6M to 0.5ML Bunsen burners have been replaced with hot plates, and directions are given for disposal of waste ( 4 ) .As a bonus, the experiment is now faster and less messy
Safety Note: Wet zinc dust can burst into flame when exposed to air; we have had fires in wastebaskets when students have improperly disposed of their residue. The residue, zinc, is classified as a law toxic hazard. The residue should be spread in a thin layer in a metal pan. As the paste dries, zinc oxide will form. The dry material can be transferred to a container far disposal in a landfill.
Literature Cited 1. Scott, L. W.; Hill, J. W.: Muto. P Chmnieol Invesilgalions for Changing limes, 4th ed.; Burgers: Minneapolta. 1984. 2. Hassell. C. A . Carver. E.. and Hill, J. W. Chmziml Inuestigdions for Chonging nrnes 6th ed.: Macmillan, 1992. 8. McComick. P. D.J. Chern.Edu, 1915.52, 102. 4 . PIudenf Practices for Disposnl ofCkrnieals for Lzbomtories;National Academy Press: Washington, D.C., 1983.
Jeanne Robinson Seminoe Comm~n~ty Co cge Sanlora. FL 32746 Wayne Morris Morris Forensics, Inc Goldenrod, FL 32733
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Journal of Chemical Education
