LINDAWOODWARD The UniversityofSouthwestern Louisiana Lafayene,LA70504
chemistry for kids Chemistry Abounds
An Educational Outreach Program Designed for Elementary School Audiences Henry J. Tracy, Chris Collins, and Paul Langevin University of Southern Maine, 96 Falmouth Street, Portland, ME 04103 "Chemistry Abounds", a now popular traveling chemistry show, was created by the University of Southern Maine Chemistry Club. Consisting of a dozen students, the USM club has staged chemistry demonstrations for approximately 2200 elementary school students i n over 16 Portland-area schools. The USM Chemistry Club, a preprofessional club affiliated with the American Chemical Society, is supported by the USM Chemistry Department, the USM student government, the USM Office of the Provost, and the Maine Local Section of the American Chemical Society. The purpose of "Chemistry Abounds" i s to illustrate that chemistry can be fun and also to awaken curiosity in the young audiences. "The Phases of Matter" program has received enthusiastic media attention including a front page article i n the Portland newspaper as well as reviews on two Maine television stations. In a typical demonstration, members of the club and their faculty advisor, donned i n safety goggles and lab coats, demonstrate extraordinary feats with ordinary substances. Focusing on the scientific process, the demonstrations stress three fundamentals: observation, prediction, and formulation of theory. The students are encouraged to play the role of scientist. They are challenged to observe the experiments, to predict the outcome, and with help from USM members, arrive a t theories. Following the demonstrations, which last between 45 to 60 min, the USM group invites its young audiences to participate in several hands-on experiments. The phases of matter is the general theme of the elementary school program, and it is offered i n a modular format. Such a format permits logical division of the program among the presenters, easy expansion or substitution, and allows the Chemistry Club members to perfect their own presentations. The nine modules are listed in the table and described sequentially below.
I
Modules for Phases of Matter Program 1. solid, liquid, or gas? 2. about water 3, acids, bases, and salts
4. 5. 6.
7. 8. 9.
a. red cabbage indicator b. solutions and electricity C. supersaturation change of phase about carbon dioxide quick freeze with liquid nitrogen chemical reactions a. two liquids make a solid b. oscillating reaction balloons go pop? invisible ink revealed
9 Module 1 The three phases of matter are presented with the aid of colorful posters. The familiar three phases of water are used to introduce the water molecule, the most fundamental unit of water. Each phase i s discussed hriefly in terms of how fast the molecules are moving. In a solid the molecules are moving slowly, so i t retains its shape. In a gas the molecules shoot around in all directions, so i t expands to fill its container. This leads naturally to discussing some of the properties of water, the subject of modules 2 and 3. Module 2 Water's purity and its ability to dissolve many compounds are discussed. The ubiquity of water is noted, including the percentage of a typical elementary school pupil that is water.
Volume 72 Number 12 December 1995
1111
Module 3 Three visuallv excitine demonstrations are used to oresent acids, bases, and salts. From dissolving substances in water. we eo to testine household products for whether they are aGds or basesin water by'using dilute red cabbage juice a s a colorimetric indicator. An acid and a base, brought from the laboratory, are added to l-L graduated cvlinders containine the ~ u m l eindicator as references. &sequently, a vari;ty of Eomkon household products are tested and compared with the reference solutions. The next component of this module focuses on salts dissolved in water. The ability of solutions of salts to conduct electricity is demonstrated with a light bulb with electrodes that can be immersed in a beaker of solution. Sugar water does not cause the bulb to light while salt water does. For the final component of this module, the amount of a salt in a solution is demonstrated dramatically by seeding a supersaturated solution of sodium acetate and observing the subsequent crystallization ( I ) . The changes of state of water, carbon dioxide, and nitrogen are the subject of the subsequent three modules.
-
Module 4 As- a~n introduction to the effect of pressure on chanee of state, students watch the expansioi of partially inflked balloons within a laree sidearm Erlenmever flask when it is evacuated with a vacuum pump. his visually estahlishes for the audieuce the presence of the vacuum. Then the balloons are replaced with cold water. Again the large flask is evacuated. and the audience watches the water come to a boil. member of the audience is invited to place their hands on the outside of the flask in order to confirm that the water is still cold. This is compared to a flask of boiling water a t atmospheric pressure, illustrating the dependence of ihe boiling point. ~~
~
~
~
~
-
Module 5 To reinforce the concept of molecular motion and change of phase, dry ice (solid carbon dioxide), a solid that does not melt a t atmospheric pressure, is introduced. Some properties of carbon dioxide gas are demonstrated. An Erlenmeyer of warm water and dry ice serve a s a carbon dioxide generator that is used to extinguish a flame and to inflate a halloon that is heavier than air. Module 6. Next, the students are shown boiling liquid nitrogen poured from a Dewar into a beaker. The cold temperature of the boiling point of nitrogen is discussed and then demonstrated by freezing solid some familiar flexible ohjectsa flower, a tennis ball, and a balloon. At this point the students usually seem to have an understanding of the relationship of the macroscopic phase of matter with the microscopic molecular theory of matter.
1112
Journal of Chemical Education
Chemical reactions are the subject of the next and final three modules. First, the audience is introduced to some chemical terminology, namely "reactants" and "products", in the context of baking cookies a t home. Module 7 Solutions of silver nitrate and potassium chloride are presented a s the reactants. The solutions are mixed together. vieldine a white ~ te chloride). As a n . r e c.i ~ i t a(silver example of a more complex reactant-product relationship, the Hriaai-Rauscher oscillatin[! reaction i s performed 2 The dramatic color changes allow the experimenter to elicit observations from the audience. The response often reaches a feverous pitch if the experimenter "does not notice" the dark color and professes that the solution remains the lighter color. At this point the elementary school students excitedly volunteer their observations. Module 8 The introduction of a spark to various gas-filled balloons is the highlight of this segment. The program proceeds from helium to oxygen to hydrogen, to teach the audience about the different reactivitv of various eases. The audieuce is prepared for the subsequent loudbang when the final balloon containing both hydrogen and oxygen is ignited. Module 9 As a finale, a message previously written on a poster board with phenolphthalein indicator, is "developed" by soravine the board with a dilute solution of sodium hvd r o x i d e r ~this t point bright fuschia letters appear. After the "formal" demonstration. we offer two tables. One is set up with red cabbage indicator and a variety of household ~ r o d u c t sto .test. as well as a lieht bulb with electrodes to test for dissolved electrolytes. ~ i other e table is set up with solutions of polyvinyl alcohol, sodium borate, and food coloring for making slime. We have found the major strength of this program to be that we are able to mix fun with science education. The Chemistrv Club members eniov the demon- . ~erforming . strations-and eliciting responses from t h e elementary school students. We targeted fourth graders initially hecause we believe that science is still fresh and possibly a n exciting subject for them. The club has expanded its repertoire to target middle and high school students with "The Transfer of Energy" program. We wholeheartedly believe if we can share some of our enthusiasm for science with this audience, we will he contributing to science education in our community. Literature Cited 1. Shakhashiri. B.2. Cherniea1~rnonstralions:AHondbook for k c h e r s of Charnialry University of Wisconsin: Madlaon. WI.1983;Vol. I. p 27. 2. Shakhashiri. B.2. Chernlm1D~rnonstrofions:AHondbokfor TachersofCh~rnislry; Univeisitj of Wisconsin: Madison. WI, 1983: Vol. 2. p 248.
