letters Proper Waste Disposal Procedures To the Editor: I was oleased to note the e m ~ h a s i slaced uDon the envil Chenironment in the May 1992 edition of tLe ~ o u r n aof cal Education. At the same time I am disturbed bv a n article which was placed in this edition. On page 414 of the article, Chemistry for Kids [1992,69, 4131, the use of AgCI, AgzCr04,and PbIz is suggested. In the same article the following appears: "Liquid waste is poured into a bucket under the table during the show and later emptied down a toilet" (p 413). In the introduction to the same issue (p 346) you say that "Chemists can help with understanding environmental issues by providing the data and theories to define the problem, assess its seriousness, and explain its causes". You go on to say that "Certain chemical species are notorious for their toxic reactions when they enter the environment in unnatural forms or concentrations. Two such major pollutants, heavy metals .....". I t seems unfortunate that an article like Chemistry for Kids, which contradicts today's ethics, would ever come to print, especially in a n issue devoted to environmental articles. I recognize that the concentrations of these ions is low, however dumping ions of this type i n any concentration is environmentally unacceptable. I believe t h a t science teachers must assume a greater responsibility in ensuring that this type of activity does not happen. If salts of this
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type cannot be disposed of properly, then don't do the experiment. Karl Clarke Science Depanment Pickering High School Ajax, Ontario To the Editor: In response to Mr. Clarke's letter concerning the article about the Chemistrv Is Fun show. I would like to acknowledixe th:~the hns nindr a valid objection to myd~sprinlrncth~r~ls. On t h c b o t h ~hand, ~ unr shunld alio ronsidrr the lolloun~g. 1. The precipitates of AgC1, Ag2Cr04, and PhIZ are of extremely low solubility, havingKSpvalues of 1.8 x 10". 9 x 1012,and8.7 x loq respectively 2. The precipitates mainly end up in a land-fill and are in such small amounts that they are acceptable in our area.
I am quite appreciative of Mr. Clarke's remarks, and I have modified my oresentation in this manner: I make a point of showingthe students that I a m pouring these liquids and vrecivitates into a j a r marked WASTE. This eives me the opport;nity to explain that some chemicals have to be handled carefully when being discarded. I tell the audience that I take the waste material back to the school laboratow to dispose of i t properly. . S ~1 Ithenk .\lr CI:irkr liw hisuhjectiun because he h a : i g ~ $ m me rhe Incentlw to nnoluw thc Chcmian. Is Fun r h ~ w . Marie C. Sherman 7602 Weil Ave. St. Louis. MO 63119 ~
