Consumer Information. Manufacturine Chemisfs Aweletion. 1825 Connecticut Avenue. ~
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NW. washington. DC 20009. American Chemical Society, 1155 Sixteenth Street, NW, Washinpton, DC ZW36. Art Hazards Information Center, 5 Beekman Street,NewYork, NY 1W38:(2121 227-6220. chemicsl ~ ~~ ~ ~ 2501 ~ ~ M. str&, i ~ ~~ t. wi . ,~. w~ f~h . nc i ~2 ~~ 3t~7~(202) :~ , 887~1100.
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Teachino Aids ~~
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Conrumer Chemistry Teaching Aids. Unigraph. 1401Broadway, Seattle. WA 98122. Public IntereatSuftwsre - Nufri~Byt~,TheCenterforScienceinthePublieInterent,1155 S. Street, N.W.. Washingtan. DC 2W09.
Useful General Texts Press. 1979. Shuman, A , "Chemistry In Our Changing World,'Prentice-Hell, Nelu York. 1380. Steine. William R., "Chemistry for the Consumer," Allyn and Bsmn, 1978. (revised as "Applied Chemistry? 2nd ed.. 19811.
Sources of Demonstrations ~~~
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The Science Teacher, National Science Teachers h i a t i o n . 1742 Connecticut Avenue, N.W. WaahinplonOC 2WW. Books like: Shakhashiri. Bassan Z.,"ChemiealDemonauationn:AHandbmkfor Teachers of Chemistry," University of Wisconsin Press. Madison. 1983.
Sources for Background lnformation ACS Puhlicstians such as ACS, CHEMTECH, CHEMUNITY (which mntaine a copy of Chem Morreral from the Offlee of High School Chemistry, (1155 16th Street, N.W., Warhineton. DC. 20036).
JOURNALOF CHEM~CILEDUCATION
Boudresu,J. C.."FoodTasteChcmistry."ACSSymposiumSeries 115,AmericsnChemical Society, Washington, DC, 1919. Scalsn, R. A. (Editor), "Flavor Quality: ObjectiveMearurement,"ACS Symposium Series 51, American Chemical Saiefy. Washington, OC. 1977. Getz, M.E.,"Paper and Thin Layer Chromstogrsphie Anslpia of Environmental Toxicants,'' Heyden & Son Ltd., Philadelphia. 1980. Nassau. Kurt, "The Phyain and Chemistry oECo1or.i. Wiley. NeuYork. 1983. Allen. R.L.M.,"ColourChemistry? Thomas Nelson and Sons, London, 1971. Were, George W."Pesticides: Theory and Applications."W.H. Freeman and Company. San Francireo, 1983.
How to Turn on an Electric Light F. H. Westhelrner Harvard University Carnbrldge, MA 02138
A symposium on what to teach the citizen, held a t a meeting of the American Chemical Societv. will inevitablv come to'the conclusion that the citizens of this countr; really ought to learn some chemistry. If I endorse this conclusion (as I shall), I shall be preaching to the converted. But my thesis is much more extreme. I maintain that the history of civilization that is presented in our schools, colleges, and universities should contain a strong element of science and technology-mostly technology. The story of humankind is usually presented as political history and, occasionally, as economic history. It is only infrequently, if ever, presented as technological history. Yet technological history is a t least as important as political or economic history. I am not speaking here of the history of science, interesting as that suhiect mav be. but of historv as science-the history of civilization9s;n terms of technoiogy. T o a considerable extent, it is inventions that have made the difference to mankind. Political organization can easily prevent progress; but the hestthey can doon the positive side is to create an atmosphere where invention can-thrive. The actions of the Goths and the Visigoths and the Vandals, continued by the intellectual stagnation enforced by the Inquisition, slowed the progress of technology in Europe for nearly a millenium; other examples of stultifying political activity can easily he found. Economic policies can encourage inventions, but cannot create them, although sometimes economists talk as if Columbus could have come to America on a Boeing 747 if only Queen Isabella had put up a little more money.
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I am convinced that the invention of smelting is second only to the invention of writing in importance to the development of civilization, and that the invention of stirrups, t ~ ~ ~ ~ ~ and of the deep keel for sailboats, and of rotation of crops, and of the roasting of limestone to produce lime, and the invention of glass, and of gunpowder-as well as many other inventions-constitutes the real history of humankind. This is not necessarily coincident with progress; many inventions have been concerned with better methods of killing. Until the introduction of nuclear weapons. . . however, the net effect of invention was, arguably, to benefit mankind; nuclear weapons may have changed that balance. School children are Bometimks taught about the Wars of the Roses in England. Those wars can, in my view, he summarized by York shouting, "I'm going to be King", and Lancaster shouting, "No, I'm going to be king." I suspect that few readers know who did become king, and fewer care. But the invention of eyeglasses has probably benefited half the people who see this manuscri~t. My views on teaching can he summarized as follows: First, nonscientists, and especially lawyers and MBA's, play a prominent, perhaps a dominant, role in running America. Second, science and technology provide most of the solutions that are available for problems today, and at the same time cause many of those problems. Conclusion: the scientific education of nonscientists is vital. The people who make the important decisions in our technological society ahsolutely must know something about i t n i t only something about human relations and psychology and history and economics and art, but also something about how the physical machinery of our society.works. I t seems to me that we have to induce nonscientists to learn very much more science than they now do. Not much more than a hundred years ago, most educated people had some idea of where the materials they used came from and how they had been made. Mauv individuals had been down to the d&ks to see ships load and unload and had stood by a forge to watch a blacksmith at work; they had probably seen agriculture up close and knew what was done and how. Soap may still have been made in the kitchen; the physician could do little for his patients, and what he could do was not mysterious. The situation is quite different today. Many of the people who run this country are, strangely, among those who know least about how it works a t the technical level; they are managers of people, not things. Today, the highest quality products we have in America are imported: German, Swedish, and Japanese cars are better than ours; Japanese cameras and TV sets dominate the market; the Japanese make more reliable computer chips than we do. We buy Scandinavian furniture and Italian shoes, Swiss or Japanese watches, Irish linen, Thai silk, Mexican tiles, French dresses. Whether this situation results from the lack of technological knowledge on the part of our managers is of course matter for debate; but riding my hobbyhorse as hard as I can, I want to swread the word to everv Middlesex classroom and dorm: the technicians are coming. Enough of generalities. I can best illustrate by ideas and provide an example of the kind of thing I believe we should teach by discussing an important topic: How to turn on an ~Iectric lieht. .-...~. - -~ ---.. Of course, everyone knows how to turn on an electric light. You walk oyer to the wall switch, flick it, and the light goes on. A young child can do it, provided the child is tall enough to reach the switch. ~ccasibnallythe light does not go on because the bulb has burned out, so you have to go to the hardware store and buy a new bulb. I t costs about $1. Then you have to unscrew the old bulh and insert the new one. The lieht eoes on aeain. That is all there is to it. That i u all there is to it unless you start asking questions. Presumnbls the hardware store rot the bulh from thc manufacturer, who had to make i t from copper and brass and glass Volume 62
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and tungsten and whatall. And if you get that far in your ~uestions,vou might then ask how one gets comer and brass andglassand tunisten. You might even begin;;worry about what elertricity is, and how it is that it flows along the wlres that are connected t o the switch. But those can open a can of worms. There is almost no end to them. Before you are done, you may conclude, as I have, that you cannot turn on electric light without involving almost the entire industrial aooaratus of the world. brineine . ~. ~.in not onlv metallurgy and electrical engineering, but the petroleum industrv and international trade. I'robablv there is no sinele indivihual on earth who really knows how to turn on anelectric light, and if you want to know even a little about it, you will have to study chemistry and physics, geology and electrical engineering, and much more. the lawyers and businessmen who manage our At affairs hire scientists, and perhaps harbor a trace of contempt for people who are so-easily bought. Many years ago, my father stopped to buy an evening newspaper, and found the newsboy lost in admiration of a picture of a strongman on the cover of a magazine. "Doesn't look like he has many brains, tho, does it?" my father inquired. "Brains," the newsboy snorted, "You can buy brains." Regrettably, it is true. But if a nonscientist who knows no science hires scientists, he may hire plausible charlatans, or a t best he a t the mercy of people who make statements he cannot evaluate. Leaders in America should not be at the mercy of uninformed decisions concerning the pronouncements of those experts. Even if you do not want t r i know in great detail how to turn on an electric light, it seems to me that all of those who, on graduation from college, join the company of educated men and women, should know what it involves. G. K. Chesterton said that "If a thing is worth doing, i t is worth doing badly." Only if you can do something badly can you understand someone who does i t well. Our lawvers and business managers and our writers ought to be able to talk to scientists and eneineers and make informed decisions with respect to technological matters. With this in mind. let me oven the can of worms related to turning on an electric light, and demonstrate something of what it involves. The manufacturer of the light bulb must use glass for the envelope. Glass in turn is made from sand, lime, and sodium carbonate. Sand can he shovelled up from the beach or elsewhere and washed; it is then suitable for the manufacture of glass. Lime is made by heating limestone. The Egyptians did i t a t least by 2000 B.C. They did not know exactly what the heat did to the limestone, but heat changes many things, and they knew that the resulting material was changed, even if they did not understand it. Today we write CaC03 CaO + COz
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and we may wish to teach what such an equation means. But obviously that is a modern formulation. Since the ancient Egyptians made lime-and glass-without knowing the chemistry-without the concepts of elements and. atoms, much less those of stoichiometry, thermodynamics, and kinetics-we have to ask whether a knowledge of chemistry is essential to turnine on a lieht. That's a real auestion. not a rhetorical one. T o answer it, i t is necessary to differentiate technology, such as the ancient process of making glass, from science, which explains what happens and why; it is mostly science that we teach in our schools. I t is in fact necessarv to learn science as well as technology t o make a light bulb, b u t that is not obvious. I hope that I can demonstrate i t later on. The third ingredient, in addition to sand and lime, required for the manufacture of glass is sodium carbonatesoda ash in the trade. Soda ash resembles potash, potassium carhonate. The latter was, for many years, made by extracting wood ashes with water, from which the name potash was derived. In the ancient world, soda ash was extracted from a
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few dried lakes in deserts; the most prominent were dried lakes in lower Egypt, partway between modern Cairo and ancient ~lexandr-fa:~ i a s was s made by heating these ingredients together. Later much Greek and Roman glass was made with potassium carbonate-potash-instead of or in addition to sodium carbonate, presumably because of the difficulty in obtaining the latter. But during Greek and Roman times, the supplies from wood ashes and desert lakes were sufficient. Population was small and the uses of glass limited. The question of what glass is, of what happens when one heats soda ash and lime and sand together, was not asked and if i t had been askedcould not have been answered. We write CaO + SiOz CaSiOa SiOa + N&03 NazSiOa + Cop
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but that of course involves knowledge acquired only 200 years ago. The Egyptians and Greeks and Romans made beautiful glass without that knowledge. Pareutheticallv. .,elass was imoortant in the historv of mankind and in ancient trade. I t was carried over the silk road to China a t the time of Christ and exchanged for silk: it wasabout theonly product, except for gold, th; the Chinese would arceot from the Romans. about theonlv thine that the Romans could make better than they cou6. imagine the breakage problem in taking glass bowls 6000 miles from Rome to Sian over mountains and deserts by donkey. Glass beads bought Manhattan. If you had no glass and did not know that it could be manufactured for very little, you would prize i t highly. It is heautiful and lacks only rarity to be the eauivalent of semiorecious eems. ' B the ~ latter pariof the 18th century the demand for glass had overwhelmed the supply of both sodaashand the potash that could substitute for it. In 1783 Louis XVI ordered the French Academv to offer a orize of 2400 livres-about 25 lb of silver-"to discover the-simplest and most economical method of decomposing salt on a large scale, in order to secure from i t theilkallthat serves as& base:. .the cost of this mineral alkali not t o exceed the price a t which i t can be extracted from the better foreign sddas." The "foreign sodas" of course, were obtained from the few dried alkaline lakes in the world. The orize was offered iust a t the dawn of chemistry. Antoine Lavoisier. the outative father of chemistrv. oublished the first editibn of'his epoch-making text in i789; a few decades earlier, King Louisprobably would not have had the knowledge a t hand to suggest making soda from salt. Here the science of chemistrv was needed to solve a practical problem, and the language oichemistry was helpfufin defining it. The prize was offered again each year for five years; suhsequentlyLouisXV1 had other matters on hismindmore urgent than the prosperity of the French glass industry, and in 1793 he lost interest in chemistry altogether. Incidentally, a year later Lavoisier was also guillotined; the loss to society in this latter case can reasonably be said to have been the greater. The orize for a method of makine soda ash from salt was never iollected. Nicholas Leblanc Invented a process that helped for a while to alleviate the shortage, but the chemistrywas obscure and inadequate. I t was not until 1861 that the Beleian chemist. Ernest Solvav, invented the modern process'for the large-scale and eco~omiralmanufacture of sodiumcarhonace. While there is not spare here todetail the Solvay process, but i t is of interest 6 note that the U S . production of sodium carbonate in 1983 was over 8,000,000 tons. The essential chemicals for the Solvay process are salt, lime, carbon dioxide, water, and ammonia. Of course, this means that. in order to make sodium carhonate. we must also manufactuie ammonia. As late as 1861, when ~ o l v a yinvented his orocess. ammonia was obtained hv the decomoosition of organic matter, and no commercial synthesis of it was
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available. The quantities needed today make the former sources impractical. The Solvay process could not reasonably have been invented by the kind of trial and error that led to the manufacture of lime-the science of chemistry was and is necessarily involved. This is even more true for the manufacture of ammonia. In all of this discussion of the historv of the manufacture of glass, and hints as to the chemistry involved, I trust that you have not lost track of the primary purpose of this discussion-explaining how to turn on an electric light. I have been talkinr! about glass because i t is needed for the envelooe of a light h b . ~ e i are e the materials we have so far fo;nd as essential: Primary Materials
Sand Limestone Salt Nitrogen Natural gas (for the preparation of hydrogen, which is needed for the synthesis of ammonia)
Secondary Materials
Lime Hydrogen Ammonia Carbon dioxide
But obviously we have just begun in the quest of the things needed to turn on an electric light. The base of the bulb is made from brass. Brass isan alloy of about 70% copper and 30% zinc. T o turn on an electric light, we shall have to consider metallurgy. The historv of mankind is intimatelv concerned with the discovery and: the use of metals. The dekelopment of civilization has often been characterized as oassine from the Stone Age to the Bronze Age to the l r o n - ~ ~Reasonably e. pure copper was manufactured by the smelting of copper ores before 3000 B.C., and the Egyptian pyramids were built with tools of work-hardened copper-not steel, not iron, not even hronze. Alloys such as brass and especially hronze were known in the medieval and ancient world. What has the modern world-what has modern chemistry to offer? I douht that world history is ever taught from the point of view of metallurev. I rather douht that eeneral chemistrv is ever presented ?;om that point of viLw. With respect to world history-well, possibly historians would not agree with my general thesis concerning the importance of technology. Or, alternatively, perhaps they are undereducated with respect to metallurgy. My proposal is that we, the teachers of science, set about to see to it that that deficiency does not occur in the next generation. As for chemistrywell, there are several reasons to underplay metallurgy. One is that metals can mix in many proportions in alloys, so that the law of multiple proportions, and therefore the idea of chemical compounds, could not easily have been deduced, and cannot easily be taught, from the study of metals. In fact, when intermetallic compounds are formed, one finds materials such as CusZn7 and KHg13 and Fe3C that do not easily lead to the concept of valence. Chemists have tended to hide such compounds under the rug, and pretend that they do not exist. Chemistry developed and has been explained in terms of such compounds as carbon dioxide, sodium chloride, and sodium carbonate. Perhaps one should hide, or anyway delay, recognition of the "strange" intermetalliccompounds, but I question whether is is good pedagogy to ignore the smelting of metals and instead to teach quantum mechanics to freshmen. The chemistry of smelting can he regarded as the intellectual link between the development of ancient civilizations and modern industry. The availability of bronze tools, including, of course, the tools of warfare, changed the world, and it was more important that hronze knives and tools were invented than who wielded them. Whether one cuts the stone for buildings, or carves hieroglypics, or kills one's neighbor with a stone tool or a hronze one makes an enormous difference in terms of efficiency.
The ancient Greeks and ancient Chinese made superb bronze castings; we can do no better 2500 years later. In the Middle Ages, metallurgists could smelt zinc and make hronze, could assay for copper or silver or gold in ores, could separate gold from silver, and silver from lead, and analyze quantitatively for the precious metals. One of the great metallurgists of modern times, and a leading historian of science is Cyril Smith of the University of Chicago and later of MIT. He collaborated with a German scholar to translate a 16th century text on metallurgy. When I read about the separations and analyses that they could perform in the 1500's, I commented to Smith that 16th century metallurgy was solendid. He a ~ r e e dthat this was so. I then suggested that chis cnnclusio~;'could be reworded, for example, ;;, state that "Sou metallurgists hnvrn't learned much in the last 400 years, have you?" His answer established an important prin.ciple in the understanding of the history of civilization. He pointed out that, in any discipline as important to mankind as metallurgy, it takes a long time for science to catch up with the results of millenia of empirical investigation. Well, by now science has caught up-fortunately, because the metallurgy of the ancient and medieval world is inadequate to modern needs. Part of this inadequacy is due to the huge quantities of materials that we now require for a high standard of living for the enormous world population. Even oeonle in develooine countries use much more metal than b a s t h e average in imerica only a few centuries hack, and the quantities consumed by the nearly a billion people in the developed countries is fantastic, creating problems that require all of modern science to he solved. Most of the rich copper ores in the world have long since been mined. The ancients found the highly colored copper ores, mined the best, broke i t up, and hand picked the colored pieces-for example, the basic copper carhonate-that they used for smelting. But the supply of basic copper carhonate-more familiarly known as malachite-is grossly insufficient to sunnort the coooer .. industrv as we know i t todav.". and.. when some malachite is found, the lovely blue mineral is regarded as a semiprecious stone and not as ore. The United States alone uses over a million tons of copper a year. In order to get such vast quantities, we and the rest of the world have been forced to ;se ores that are much poorer, but fortunately much more abundant, than deposits of malachite.It takes chemistry to identify copper mLerals in small quantities in quartz, and mechanical machinery to mine and to crush the ore, and chemistry again to separate the copper mineral from the gangue-the useless quartz and granite-and from the ores of other minerals; often copper sulfide and zinc sulfide occur together. There is no way in which the lowerade ores still left to us could be seoarated bv hand in sufficient quantities for our needs, nor, in particular, to make the conoer wire needed to transmit electricitv from power plants io our light switches. Using ancient methods, one could indeed make a sample of copper for exhibit. Making a million tons a year is a different matter. In oractice, the separation of ore from gangue is commonly carried out by flotation. Although some ex&nples of flotation are centuries old, the principles of surface chemistry and of detergents and of the structural theory of organic chemistry are among the pieces of science that are needed for modern industrv. Then several ch&ical processes are require$ to convert the ore to metal. Sulfide ores have to be roasted t o nroduce oxides or metals plus sulfur dioxide. The amount of sulfur dioxide liberated into the atmosohere bv the roasting of copper ore or zinc ore is considerable; every time anyone turns on an electric light, he contributes to acid rain and the destruction of the lakes and forests of New England. This is something, -. too,. that the incioient lawyers and businessmen who are now in our universities ought to know-and understand. A.
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