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edited by: RICHARD STEINER University 01 Vtah Salt Lake City. UT 84112
Stimulating an Interest in Chemistry in Middle school Students Charles W. J. Scaife Union College, Schenectady, NY 12308 Many elementary and middle school students experience excitement in science primarily through experiments. Unfortunately the amount of laboratory work has been decreasing in many school districts because of budget cuts, more stringent safety requirements, and other reasons. Special summer courses can bring back the thrill of laboratory experiments for a t least a few students and perhaps stimulate those students and some of their friends to take more science courses when they reach high school. Summer courses have already been described for gifted fourth and fifth graders ( I ) , gifted fourth through sixth graders (2), gifted fifth through tenth graders (3), and a science camp for ninth and tenth graders (4). The purpose of this paper is to describe a short concentrated laboratory course for middle school students. Union College has offered two-week courses of ahout twohour duration each day as part of its Summerskill enrichment program designed to stimulate interest of sixth through tenth graders in particular subject areas. A chemistry-based laboratory course has heen developed and has been offered for three consecutive summers. The course encourages students to: 1)work with a variety of chemicals and equipment; 2) make observations in order to gain respect for uncertainties in both qualitative and quantitative evidence; 3) interpret results, therehy developing imagina-
790
Journal of Chemical Education
tion and creativity; 4) draw conclusions based on evidence, thereby improving decision-making skills; 5) follow both written and oral instructions in asafe manner; 6) understand some of the characteristics of science, that its ideas are suhject to change hecause they are conceived on the basis of experimental evidence that often has considerable uncertainty; and, most importantly, 7) experience a healthy halance of the fun, frustration, and excitement of chemistry. T o meet these objectives the following experiments have been devised.' Densitv. Students identifv unknown solid samoles that are both rwulnrly shaped csphere, cylinder, or rectangular solid) and irregularly rh;~pedand rmgc fnrm Plexialss r1.16 g r m ' l to lead rll.3 g em". Manipulating Glass Tubing (5).Studentslearn about the eharae-
teristics of soft glass versus borosilicate glass and how to obtain differenttypes of burner flames. They learn to cut, fire-polish,bend, and draw out glass tubing. They also make crazy straws and other
Presented at the Eighth Biennial Conference on Chemical Education. University of Connecticut. Storrs, CT. August 5-10, 1984. I A copy of any or all experiments may be obtained by writing to the author.
items that are not part of the experiment. This is by far the most popular experiment. Fractional Crystallization (6). Students dissolve a mixture of two salts (one colored and one white), crystallize primarily the salt that is less soluble at law temperature, recover that salt by vacuum filtration, wash the salt carefully, and dry and weigh it in order to determine the percent of purified salt that was recovered. Chemical Cold Pack (7). Students plaee water in a sandwich bag sealed by a twistee, then place that bag and solid ammonium nitrate into a heavier-walled, transparent hag that can be sealed with an iron. This is a papular experiment because the product can be demonstrated at home. This is a short experiment, and the effects of heat or cold on the properties of several substances and on anumber of chemical processes are demonstrated by the instructor. RatioofReaetants ina CherniealReoction (8).Studentscarry out an soueous . meci~itation .~~~. reaction usine different volumes (hut constant total volumel of two cquinwlar reactant solutmns. Thr solid prduct i\filtrred. drird,and wrighrd so t h ~afplot ulclasrdnta %,ill +hew rhr partreulnr volume rnrio pwducinl: the maximum mass of product. Soft and Hard Water (9). Students learn to measure volumes in a buret in order to titrate various water samples to a lather endpoint with an Ivory soap eolution and thus to study wme of the chemical properties of soft versus hard water. They also determine the effeetiveness of several processes for softening hard water. Aqueous Ions of Transition Elements (10).Students prepare zinc amalgam and use it to reduce V02+to V2+ over a period of about an hour so that a series of color changes can be observed. On standing overnight in an open beaker V2+ solutions are oxidized to V3+. Students also reduce VOot to V02+with Feat and oxidize VOZ+hack to VOzt with Moo4-. students are challenged to discuss the colors of VOzt, VOZ+,V3+,V2+,Fez+,Fe3+, Mn2+,and Mn04- based an their evidence. Identification of Inorganic Salts (two days). Students note the physical appearance of inorganic salts and observe their behavior toward water and aqueous solutions of HCI, H2SOh NaOH, and AgN03. Eight possible cations and six possible anions are used. Students are also provided with an infrared spectrum to use on a iingrrprint baris. and oprration of the instrument ir den~onstrated. 'lhldes i t solubilitier nnd of colors of solidsilnd i h t i o n ~ dreprw~~drd almr s , i r h infrared sorctra
