A PLAN
for
the OPEN
HOUSE in CHEMISTRY AMY LE VESCONTE Mary Hardin-Baylor College, Belton, Texas
The simplest of experiments performed by enthusiastic students will interest visitors more than elaborate displays of apparatus or chemicals. The students, themselves, learn much from their demomtratiom and from the thought-pronoking questions of the visitors, and their interest i n the subject is deepened.
success of any demonstration depends more on the enthusiasm of the student who explains i t than on the excellence of its preparation. It should be added, however, that a t each exhibit a typewritten explanation is placed, since occasionally students desert their assignments. Only the most interested and conscientious observer will read these, while a visitor must be ++++++ very uninterested to be able to pass by an enthusiastic N OPEN house in the science department offers student without hearing a full explanation. an opportunity to the students to demonstrate It has been found advisable to alternate demonstrathe technic and ability they have developed in tions that have a definite practical application showing their laboratory work. It also gives students who do the useful side of chemistry, with a few very simple exnot study science a chance to see what takes place in a periments on the theory of chemistry, such as the eleclaboratory, and by interesting these students it may trolysis of water, and with several experiments for bring about a substantial increase in science enrolment entertainment only, showing the side of chemistry that is "fun." the following term. These open house events have revealed a most surAt Mary Hardin-Baylor, a liberal arts college for girls, the chemistry department holds an open house prising interest, on the part of casual visitors, in exnear the close of each fall term. A few weeks before the tremely simple demonstrations. A freshman bending date, students with artistic talent are enlisted to make glass tubing and blowing small glass bulbs always has posters of chemical apparatus or symbols to announce an admiring audience. Many of the guests take uuthe event. Usually over half of the student body and usual pieces of glass with them as souvenirs. Morefaculty from the college find i t possible to attend, and over, students who demonstrate glass blowing usually spend from thirty minutes to two hours studying the develop their technic considerably during the two hours exhibits and demonstrations throughout the three of the exhibit. Writing with chemicals is always simple to explain laboratories. To make the laboratory more festive, flowers in season are interspersed with the exhibits. and effective in creating interest. As they arrive, the These are arranged in flasks, beakers, casseroles, and guests register in a book made of yellow paper, the evaporating dishes. One of the most dective of these pages of which have been sponged with potassium flower arrangements is a single bud in a volumetric thiocyanate, potassium ferrocyanide, or potassium flask, with leaves immersed in the water, which is ferricyanide, and dried. Although all the pages look tinted with eosin. alike to the casual observer, when a solution of ferric Every student enrolled in chemistry, even in the be- chloride is used as ink the writing may appear either ginning classes, is asked to assist in the open house. as red, blue, or green. A most popular souvenir is a Some of these meet the guests as they arrive, and usher piece of white paper coated with colorless phenolthem through the laboratories in a definite order, thus phthalein, and cut in the shape of an Erlenmeyer flask. avoiding confusion. The more capable students pre- Students enjoy seeing the red appear when they write pare and demonstrate one or more of the experiments. on these with sodium hydroxide. Usually two or more students are assigned to each desk Other entertaining features are found throughout the to perform the experiments or to explain the significance laboratory. The "educated moth balls," fire-writing, of the exhibits placed there. This makes i t possible for and chemical flower gardens are familiar ( I ) , (2). One them to relieve each other to visit the other laboratories. demonstration that furnishes entertainment through the The students enjoy the responsibility that is given laboratories is "chemical music," a group of beakers, them, and respond by taking an active interest in tuned by varying the amounts of water in them and armaking the occasion a success. They make many ranged in order to play a favorite melody when tapped helpful suggestions and arrange the final details of the with a glass rod. experiments with much care. This interest is contaInterspersed with the experiments in action are exgions, and the visitors are affected by i t as soon as they hibits of work that have taken more time to prepare. start their tour of the laboratories. Probably the "Chemical jewels" include huge crystals of copper sul-
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fate and alum (3) and various crowns and baskets of potassium dichromate (4) prepared as optional experiments by students. Lead trees (5) are often on display, and "depression gardens" (6) add color to the laboratory tables. Among the more practical exhibits are demonstrations of methods of distinguishing cotton and rayon from wool and silk, or the methods of purifying and softening water, or the action of baking powders. Crystals of potassium permanganate dropped into a beaker of water and then heated show convection currents in the form of pink streaks through the water. A model of a sulfur mine is especially interesting to people in Texas (7). Meat, flowers, and mercury are frozen with dry ice. The steps in making the four types of rayon are demonstrated by an advanced student. In all these demonstrations, the explanations are made as complete as possible, without the use of scientific terms, and the possibility of making a practical application of the knowledge is stressed. Many girls think that chemistry is useful if they can learn something about cosmetics. Tooth paste, fingernail polish, cold creams, and hand lotions made in the laboratory are on display, with a student to demonstrate them. Some of the favorite formulas are: Vanishing Cream Mix equal parts by weight of calcium carbonate and zinc stearate in a casserole. Add glycerin, diluted with a n equal amount of water, t o the desired consistency. Add perfume and color a s desired.
Vanishing Cream Heat 100 grams of stearic acid t o SOT. I n a separate beaker mix 1.5 grams of potassium carbonate, 35 grams of glycerin. and 300 cc. of water. Heat this mixture t o 8O0C. Add to the melted stearic acid, stirring rapidly until thick. Stir in perfume as desired. Let stand a few days, stirring occasionally.
Cold Cream Mix equal parts by weight of spermaceti, white beeswax, and lanolin and melt in a quantity of mineral oil equal to the combined weights of the solids. Heat t o 80% For each 15 grams of oil, add a gram of borax dissolved in 15 cc. of water, heated to the same temperature. Stir until cool.
Hand Lotion Soak 4 grams of gum tragacanth in 300 cc. of distilled water overnight. Beat with an egg beater until smaoth. Add 25 cc. glycerin. 15 cc. alcohol, and perfume and color as desired.
One display that always attracts interest is the "chemical girl," a group of fairly well-known substances which added together would have approximately the same percentage composition as the human body. The name is derived from the placard that states that when mixed properly, the matekials would make a onehundred-pound girl. The substances used are: Coal Water Ammonium hydroxide (conc.) Calcium fluoride Phosphorus Sodium chloride Sulfur Magnesium ribbon Iron nails Potassium hydroxide Iodine
The advanced classes in chemistrv prepare some more impressive demonstrations, such as the making of ether, carbolic acid, or a coal-tar dye. The classes in analytical chemistry attempt to explain the importance of their work by demonstrating typical experiments. These, however, usually receive less attention than the simpler and more entertaining exhibits. As a fitting climax to the open house, the guests are invited to a chemistry tea table, set with filter paper for doilies, flasks for candle sticks, and an evaporating dish for flowers. Glass tubes are used for tea sippers. At each end of the table 5-liter flasks of tea are siphoned into beakers. The sandwiches and cookies cut in the shape of chemical apparatus are served on large watch glasses. One year the home-economics department cooperated by making baking-powder biscuits using concentrated hydrochloric acid, a possibility that was explained by an exhibit in the laboratory. The open house is considered a success when the visitors who attend it say that they have not only enjoyed the exhibits, but also have learned something worth while. Student visitors learn that chemistry has many useful applications and that it can be interesting. The students in the department develop so much interest and enthusiasm in assisting with the demonstrations that this result alone would justify the effort and work required. It is the hope of the author that other teachers may find some suggestions in this article to make their own open-house exhibits a greater success. .
Finger-nail Polish Dissolve- -ovraxvlin "banana oil" < ~ ~ - < - ~ in - - ~ ~~- t o eive the desired consistency. Color with eosin. ------
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20.2 ib. 61 lb. 5.47 lb. 133 grams 518 grams 118 grams 64 grams 32 grams 4.5 grams 72 grams 18 milligrams
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Tooth Paste Mia equal parts by weight of powdered Castile soap. talc, and sugar with precipitated chalk equal t o the combined weight. Add glycerin, diluted with an equal volume of water, to make a paste. Add oil of peppermint and menthol t o taste.
(1) = m u , M. M.. "A successful open-house program," J. CHEM.EDUC., 8,204651 (1931); (2) JAMES, H., "Living chemicals," ibzd., 6,2260-1 (1929). L.RJ.. , "The preparation and preservation of large (3) ~ I E D N E crystals of chrome alum," ibid., 9, 1 4 5 3 4 (1932). (4) STONE, C. H.. "some experimentS in crystallization," ibid.. 7, 2170-1 (1930). G. P., "Lead trees grown in gels," ibid., 6, (5) BREWINGTON, 2228-20 ---. - - 11424>. (6) DAVIES.E. C. H., "Growth of salt flowers on coal and other solids," ibid., 11,409-12 (1934). (7) L ~ S, H.,-A ~ demonstration ~ model ~ of ~the ~~~~~h ~ process for mining sulfur," ibid., 8, 1630-3 (1931). \----,-
The nature of many cosmetic frauds and reducing mixtures is made more vivid by posters and exhibits, and many students are thereby enlightened.
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