Chemical Education Today
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Chem 13 News : Ways to Teach in the Classroom and Beyond by Kathy Thorsen
Why did we become educators of science versus English, math, or history? The decision stems from an interest in understanding our natural world and passing onto others our curiosity and love for science. Perhaps the underlying motive is the fact that we science educators simply have more fun. A Demo a Day Keeps the Students Engaged
Chem 13 News Featured Articles
Just about any topic presented in a chemistry class can be enhanced by a demonstration. Where can we as chemistry teachers find enough ideas and tested procedures to incorporate a daily demonstration into our lectures? The March and April 1999 issues of Chem 13 News contain several new ideas to use for demonstration. A new twist for the reaction of alkali metals with water is explained by Michael P. Jansen in the April issue. In addition to the initial demonstration, he describes how to test the resultant solution for the presence of ions with a conductivity meter, identify the ions with flame and phenolphthalein tests, and verify the production of hydrogen gas with the splint test. Jansen also describes a method to determine the stoichiometry of the reaction using the oxide coating on lithium metal and includes followup questions as well.
The abstract concept of Le Chatelier’s principle is difficult to teach, understand, and, most of all, demonstrate. Carole Bennett wrote “Le Chatelier’s Principle—An Analogy Demonstration” in the March issue. The demonstration uses transparent plastic disks of four different colors, which are used to model a chemical reaction between two identical initial reactant concentrations (10 of each reactant) on an overhead projector. Once the “product disks” are formed, the colored disks representing the products are removed and replaced with “reactant disks” to model the reverse reaction. After the students understand that the reverse rate equals the forward rate from the visual model, the reaction is stopped with four disks of each product and six of each reactant. The teacher then helps the students calculate the equilibrium constant. The equilibrium can be upset by adding more reactant or product disks. The equilibrium “concentrations” must be altered each time so that the equilibrium constant remains the same. The author suggests that the students keep a record of the concentrations of all species for comparison. Electronegativity as it relates to chemical bonds is another abstract idea that is difficult to visually demonstrate. “A simple electronegativity demonstration device” is proposed by Jeffrey Bracken in the March 1999 issue. This demonstration does not require any fancy equipment—rubber bands
March 1999, No. 274
May 1999, No. 276
“Le Chatelier's Principle—an Analogy Demonstration” by Carole Bennett (p 6)
“Astaxanthin Is Fed to Salmon” (p 13)
“Weird Science at Lake Nyos” by Rod Benson (p 18) “Salt in the American Civil War” by Paula Borinsky Hendry (p 18) “A Simple Electronegativity Demonstration Device” by Jeffrey Bracken (p 7) “Replacement for the Haber Process” by L. J. Brubacher (p 19) “An Organic Logical Puzzle” by Carlos M. Castro-Acuña (p 1) “Microscale Gas Chemistry, Part 12. Experiments with Carbon Monoxide” by Bruce Mattson and others (pp 10–15) April 1999, No. 275
“Why Add Chemicals to Good Food?” by John B. Capindale (pp 1–3)
“An Interview with Glenn T. Seaborg” by L. J. Brubacher (pp 6–7) “Two Giants Have Left Us” by L. J. Brubacher (p1) “Chemistry on the Internet: Untangling the Web #32” by Ed Doadt (p 3) “Molecule of the Month: Historically Significant Coordination Compounds: X. Constant Valency and Kekule’s ‘Molecular Compounds’” by George B. Kauffman (pp 18–19) September 1999, No. 277
“Chemistry on the Internet: Untangling the Web #33” by Ed Doadt (p 3) “Microscale Gas Chemistry, Part 13. Experiments with Ethene” by Bruce Mattson and others (pp 6–11)
“The Reaction of Alkali Metals with Water: How to Maximize the Educational Value of this Demonstration” by Michael P. Jansen (pp 4–5)
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Journal of Chemical Education • Vol. 77 No. 1 January 2000 • JChemEd.chem.wisc.edu
Chemical Education Today
with varying elasticities, paper clips, and Styrofoam balls. The author describes and illustrates with photos how to create a bond with the paper clips hooked together, each with a rubber band attached at the end and then inserted in two Styrofoam balls (representing the shared electrons). He uses the common “tug-of-war” analogy by pulling on each rubber band to describe the model in terms of polar covalent and nonpolar covalent bonds. For a polar bond, the rubber bands need to have different elastic properties; but for the nonpolar bond, identical rubber bands can be used. This simple, inexpensive demonstration using concrete models helps students visualize one aspect of the microscopic world. If you tried the microscale gas experiments written in the April 1998 issue, then you will want to take a look at the March 1999 issue on pages 10–15. Bruce Mattson describes and illustrates two methods for generating carbon monoxide gas, followed by 10 experiments that show everything from the combustion and reduction reactions with carbon monoxide to testing the sensitivity of carbon monoxide detectors. The article starts with background information on the physical and chemical properties of carbon monoxide as well as on its toxicity and warnings about conducting the experiments. According to Mattson, the techniques used with the carbon monoxide experiments are a bit more advanced than his previous microscale gas experiments. Therefore he suggests generating the gas and conducting the experiments as demonstrations. The article also includes the authors’ Web page address that contains all of the latest and greatest improvements for this technique as well as some nice color photographs. An Organic Experience There is another sequel to the microscale gas experiments described above. In the September 1999 issue Mattson continues the series of gas preparation with syringes, this time creating ethene. The two methods used to prepare ethene are the dehydration of ethanol with sulfuric acid and the thermal cracking of a polyethylene polymer. This article follows the format of the previous articles, starting with background information on the gas being collected followed by several experiments (11 in this article) on how to use the ethene gas and examine its chemical properties. Some of the experiments include using the bromine and potassium permanganate tests to verify the presence of the alkene, testing the flammability of ethene, reacting ethene with chlorine to produce dichloroethane or soot, and using a catalytic converter from a motor vehicle to demonstrate oxidation and hydrogenation reactions of ethene. Once again, the author discusses several safety issues throughout the article. Though ethene is only mildly toxic, these experiments should be conducted in a wellventilated area due to the reagents used and byproducts produced. Most of the techniques used in the generation of and experiments with ethene are appropriate only for demonstration or use by experienced chemistry students. An organic chemistry class without a discussion of the applications to the real world is like a piece of toast without butter or jam. Since organic molecules are the basis for the structure of all living organisms as well as for the pharmaceutical, insecticide, fragrance, food, and numerous other industries, we chemistry teachers should never run out of interesting topics to use in a unit on organic chemistry. Two
recent articles focus on some very interesting molecules. The first appears in the April 1999 issue where John Capindale writes about several classes of food additives: preservatives, emulsifiers, nutritional additives, coloring agents, flavorings, and humectants. Each section briefly describes the purpose of the additive and gives specific examples of organic molecules used in each category. The author includes several structural formulas as well as references for further reading. The second article, in the May 1999 issue, focuses on astaxanthin, the compound that gives salmon, trout, and shrimp their pink color. The use of astaxanthin in the fish farm industry is discussed as well as its possible application as a neutraceutical to delay or prevent diseases such as arteriosclerosis and cancer. The chemical structure of astaxanthine is shown and compared to those of beta-carotene and vitamin A. This molecule is an interesting and economically relevant subject to discuss in the classroom since its patent held by the primary manufacturer is due to expire. Speaking of organic molecules, Carlos Castro-Acuña has devised a puzzle that includes nine organic compounds commonly found in the laboratory. The puzzle appears on the cover of the March 1999 issue. Since the puzzle was the basis for a contest, the answers can be found in the September issue. Knowledge, the Eternal Resource According to Glenn Seaborg, “we need teachers with enthusiasm for their subject who can turn kids on.” In an interview in the May 1999 issue, Seaborg states that we need to train teachers more in the content than in the methodology of teaching. It takes a combination of knowledge, passion, and patience to be a good teacher. As a science teacher, I am constantly searching for, reading about, and absorbing ideas and information to share with my students, a neverending but enjoyable task. The March 1999 issue contains three articles of interest. “Weird Science at Lake Nyos” by Rod Benson describes the natural disaster that occurred on August 21, 1986, at Lake Nyos. Benson suggests using this event as a captivating introduction to volcanoes, gas solubility, and density. He also suggests reading an in-depth article about the event in the 1987 National Geographic Magazine. Several Internet sites are also cited as sources of information by the author. If you are curious about what happened at Lake Nyos, here is where you can find out. “Salt in the American Civil War” by Paula Borinsky Hendry also discusses a historical event that can be incorporated in a science classroom. The novel Cold Mountain revolves around the hardships of civilians and soldiers during the American Civil War. The book describes how salt, an extremely scarce resource at the time, was dug up from the floors of smokehouses and reused. Hendry uses this as a basis for a performance assessment following a separation lab. The final article “Replacement for the Haber Process?” discusses a recent report in Science regarding a new electrochemical method for ammonia synthesis that can be conducted at atmospheric pressure and at a temperature approximately 570°C. The original Haber process is briefly described along with the new method. Background information on nitrogen fixation can be found in “The Molecule of the Month” column in the September 1995 issue.
JChemEd.chem.wisc.edu • Vol. 77 No. 1 January 2000 • Journal of Chemical Education
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Chemical Education Today
Speaking of “The Molecule of the Month” column, each issue discussed here contains a new article in the series of “historically significant coordination compounds”. A historical account is provided in the series that describes some coordination compounds that were important in the development of inorganic chemistry. Check out the section in the May 1999 issue along with the features on two Nobel Prize winners in chemistry, Glenn T. Seaborg and Gerhard Herzberg. Tantalizing Tidbits about the Internet As the Internet grows, so does my address book of useful Web sites. In each issue Ed Doadt introduces a new Web site in his regular column “Chemistry on the Internet: Untangling the Web”. I have picked out several “must see” sites. A fundamental site for introductory, general, and organic chemistry educators is http://www.wiley.com/college/webercises. The site is hosted by publisher John Wiley & Sons and works with several of their publications, such as Chemistry Webercises (available for downloading on the site); Chemistry Drills; and Adventures and Challenges on the Internet. Ed recommends
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the site not only because it provides students and teachers with a plethora of factual knowledge, but also because it has up-to-date information. Historical developments in chemistry are an integral and interesting part of the content we teach today. However, I know many teachers who are interested in the history but are not well-versed in all of the significant events. Doadt describes a Web site that will provide what they need to integrate history into the chemistry curriculum. The September issue describes the “Classic Chemistry” site at http:// maple.lemoyne.edu/~giunta. The site is maintained by Carmen Giunta of LeMoyne College and contains several sections of historical information as well as links to a large number of similar sites and notes on two courses (the course Scientific Thought is recommended by Doadt). I found the “Selected Papers in the History of Chemistry” section to be most useful and reliable. No matter what chemistry course you teach, this site should be included in your current list of bookmarks. Kathy Thorsen teaches at Menomonee Falls High School, N84 W16579 Menomonee Avenue, Menomonee Falls, WI 53051;
[email protected].
Journal of Chemical Education • Vol. 77 No. 1 January 2000 • JChemEd.chem.wisc.edu
