Nehemla Nae Avi Hofstein a n d David Samuel Science Teaching Department The Weizmann Institute of Science Rehovot, Israel
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Chemical h d ~ ~ h y A new interdisciplinary course for seconchy S C ~ O O ~ S
All the existing high school chemistry curricula try to show how a chemist works in a research lahoratory, emphasizing practical work, and concept formation. This approach usually does not show how these chemical concepts are applied outside the school lahoratory or that we live in a world which is increasingly dependent on the chemical industry, and on industrial research and its applications (1-2). The teaching of chemistry without discussing this industry, omits a most important aspect of modern life and, by implication, indicates that industrial achievements are not important. One result of this omission is the well publicized negative attitude of the general public toward chemistry as a whole with a consequent overemphasis in the media on the hazards of pollution, carcinogenesis, chemical warfare, radioactive waste disposal, e t ~ . These issues ate indeed oart of the facts and nrohlems of dailv life, but the publicity tLat they attract gives an unbalance2 oicture of the nature of science.. in eeneral. and of chemistrv. .. in particular. Chemistry a t school should not only produce the chemists of the future hut also train "tomorrow'scitizens" and prepare them for understanding and dealing with many problems they will eventually encounter and decisions t h e y may have to make (3). One way of introducing such problems into the school curriculum is to discuss the factors involved in the decisions on the location of a factory. These involve human, environmental, social, and economic, as well a s scientific aspects ( 4 ) . We wish to discuss the develo~mentof a course s~eciallv designed for teaching elcments of ~ndustrialchemistiy 16j as Dart of the rhemistrv curr~vulum.In Israel, the currirulum "Chemistry for High ~chool"( 6 )is now taught in the majority of Israeli schools in grades 10-12 and is based on inquiry techniques, concept formation, and a large measure of lahoratory work. We have added a course on the "Chemical Industry" consisting of a general introduction and three case studies hased on different and interesting examples of the local chemical industry (the production of copper, bromine and plastics) aimed a t chemistry majors as the final part of the curriculum. We also wish to discuss other wavs of i n c o r ~ o rating an industrial approach into the existing c h e m i ~ & ~ curriculum. Course Development A great deal has been written on the gap between industrial and academic research in chemistry, particularly a t the university level (7) and the various ways to bridge this gap. It has been suggested in this Journal (8)and elsewhere (9)that examples from the chemical industry can he used for teaching chemistry itself. At theserondary school level, very little has been done to introduce examples from the industrial chemistry into any rurriculum. This is oartlv due to the restricred timeavailable a t school, hut also to thk fact that the level of basic understandine and backeround in chemistrv reauired for understanding an industrial process, is though t d h e too advanced. addition, it was feared that many science teachers might be reluctant to teach even elementary economics or engineerinp. We have found, however, that none of these Droblems exist, if the course is planned properly. At the timeofthe establishmmt ot'the Slate of Israel, thirty years ago, there were in fact very few chemical industries. 366 1 Journal of Chemical Education
Since then,.however, the local chemical industry has grown very rapidly and bv now contributes about 30% of the total Israeli indistrial production. In a study conducted by the Science Teaching Department of the Weizmann Institute of Science ( l o ) ,chemistry teachers rated "the chemical industry" as fifth in importance out of 16 possible subjects for teacher training. Interestingly enough, high school pupils rated the teaching of industrial chemistry significantly higher in imDortance than their teachers did (.1 1.) . We therefore decided to use examples from the chemical industry to illustrate the application of concepts such as oxidation-reduction, heat of reaction, chemical equilibrium and rates of reaction. In this manner one can show that the principles studied in class and lahoratory are, in fact, part of a real-life situation and demonstrate how knowledge of chemical systems in the classroom can he applied to another sphere i.e. in an industrial plant. At the same time this unit illustrates the importance of industry to society and to the economy of the country and includes discussions of the relevant economic and environmental constraints. A different example of this appmach which was reported in [his Journal 112) is the course on the chemistrv of rocks and minerals (geochemistry) which has been introdiced recently into the Israeli chemistry curriculum. Our new option is part of the new three-year chemistry curriculum, designed for science-oriented hieh school students, many of'whom are considering emharking on a scientific or engineering career. The new unit follows a hit twn year "core" chemistry course and consists of carefully selected examples of the application of chemical principles to industrial processes. Objectlves The ohiectives of this course are 1) To demonstrate how basic chemical principles are applied to
production on an industrial scale.
2) To emphasize the importance of the chemical industry tosociety
and to the economy. 3) To develop an appreciation of the technological, economic and
environmental factors involved in chemical industry. present some specific problems faced by the local chemical industry.
4) To
In most industrialized or semi-industrialized countries there are, of course. a verv laree number of examnles from the chimical industry w h c h can he used for study. However, in order to make the subject meaningful a t the secondary school level, case studies should be chosen which fulfil the following criteria: 1 ) The studiesshuuld be based on clearly defined chemird processes which ore related to the "core" chemistry course. 2) The Inair cerhnolog) of the induatrtal procrs drwrihtd must nut
be too difficult to understand. 3) The economic and social aspects must be clear cut and easy to
explain.
4) It should be possible to include a discussion of topics such as
raw materials, manpower, energy requirements, waste disposal etc. In most cases, the consideration o f a sperific chemical industry should take incoacrount luml and other t'actora, which will determine the final choice for inclusion in the co&se.
The Structure of the Course
1) Introduction. What happens in a chemical plant; the main chemical industries in Israel. 2) Copper production at Timna. Thelocation and construction of a
chemical plant; copper production; problems of prices; the considerations leading to the shutdown of the mines., 3) Life from the Dead Sea. Bromine and bromine compounds produdion; the Dead Sea as a source of minerals; potash production; bromine production; fertilizers and pesticides; ecological problems; the production of sodium bromate; the location of a new plant. 4) The age of Plastics. PVC production; polymerization; the production of vinyl chloride; the preparation of plastic materials; the location of a plastics plant; ecological aspects. 5) Methane production using wind energy. The Case Studies
(I) The Copper Industry. This outlines the relatively simple processes of mining of copper ore, sulfuric acid leaching, and the precipitation of copper by iron scrap:
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Cuz+(,~+ Felg) Cum + Fe2+laq) This example also gave us an opportunity to discuss the economin of the process and the reasons for the shutdown of the Timua copper mines (near Eilat, in the southern part of Israel) in 1976, due to the drop in the world price of copper. (2) The Bromine Industry. A very successful and specialized industry a t the Dead Sea. The process starts with the concentration of Dead Sea hrines by solar evaporation, followed by the large-scale displacement of bromine by chlorine:
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2Br-(.,1 + CIz,) Bhm + 2CI-(.,) The use of hromine for the production of various simple organic and inorganic hromine compounds is then described, as well as the use of some of the products. (3) The Polyvinyl Chloride (PVC) Industry. The manufacture and use of plastics is now worldwide and most countries have by now at least the beginning of a plastics industry. The production of vinyl monomer, its chlorination and polymerization to PVC, are useful examples of large scale chemical processes which combine aknowledge of both inorganic and organic chemistry. Two processes for the production of ethylene dichloride are discussed:
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CHz = CHqd + CIz(,j C~H&IZ(~) CHz = CHZ(~I + 2HCI(g)+ 112 Oxg) C Z H ~ C I+~ HZO(~I I~I the production of the monomer:
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CHGI - CH&I CH2 = CHCl(,) HClb) as well as the polymerization step: n CH2 = CHCl(,)
U CHEHLW PROCESSES
Our course begins with a general introduction to the factors which affect production in a chemical plant, including the basic principles of costs and prices, the role of research and development, and the need to conserve energy and to prevent pollution of the environment. This is followed hy a brief overall introduction to the Israeli chemical industry, and then by three case studies. At the end of the course, as a form of review, each student is asked toplan a hypothetical chemical plant for the production of methane from calcium carbonate using wind energy (13).Here students are expected to apply all that they have learned from the case studies to this imaginary project and suggest the best site for the plant, the process to he used and make various other decisions. The major topics covered in the course are
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+CHz CHCIS, In each of the three case studies, the following points are discussed: (a) the need and uses of the various products and the scale a t which they are produced, (b) the considerations which determine the location of the plant, (c) the factors which determine which chemical process to use, (d) some economic and technological considerations, and (e) the energy and environmental issues.
crtr.rt'on
0x'd.ti.n-reduction
thanndynanlcs
kinetics
LOCATION OF THE PLUlT
lab07
BROMINE COMPOUNDS
mrieting
ECLODI
gasoline additives
In each case study the students are given rsrtain basic infurmation, are encouraged tu discuss prohlems outlined in the text, and are asked toreach a decision. A number of simple experiments related to each industrial process have been introduced as part of the course. For inslance, (a) the production of copper by leaching a small sample of copper ore and disnlacement hv an iron nail.. (h) of . . the small scale .nrenaration . bromine from a solution of hromide, and (c) examining the effect of the addition of a olasticizer to a . oolvmer. In order to illustrate our interdisciplinary approach, the case study on the production of bromine, (called "Life from the Dead Sea") will be described. The major factors influencine of various chemicals from the sea are -the oroduction . presented in Figure 1. This case studv starts with a discussion of the Dead Sea as a source of minerals and includes a brief description of its eeoaraohv, mineral content. and the amount of solar enerev perday per unit area available. This is then followeda;h discussion of the.world food orohlem. the need for fertilizers and the production of potash. Bromine is produced at the Dead Sea from the bromides in the "end brines" of the potash plant. Since these contain about 12 g Br- per liter, about 350,000tons of bromine are available for extraction each year. This is the starting point for discussing the various ways of producing hromine from hromide ho~utions.The alternativesare (a) electrolysis, (b) reaction with chlorine, and (c) oxidation (with, for example, potassium permauganate). The students then carry out simple experiments and with the aid of given data determine (1) the availability and the cost of the raw materials, (2) the energy needed, (3) the problem of the disposal of by-products, and (4) the technical problems involved in scaling-up to full produc-
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The worldwide need for, and uses of, bromine compounds is then discussed, such as their use as pesticides in agriculture, and their use in the oreoaration of easoline additives. The students are then ledto consider varFous aspects of pesticide production. Finally the industrial production of ethylene dihromide and sodium hromate is described, and the factors which would determine the location of a new plant for producing hromine compounds. The other two case studies (copper and PVC) follow similar lines, leading to classroom discussions in order to find answers to various problems. implementation of the Course
Most chemistry teachers in Israel (and probahly elsewhere) do nut have sufficient training in order to teach such n course, VOIUme 57. Number 5, May 1980 1 367
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without learning more about the subject matter and obtaining some guidance in teaching strategies. They also need help in obtaining materials and equipment for the experiments and in the organization of visits to various industries (14) which is an essential part of such a course. A series of in-service teachers courses has therefore heen held at the Weizmann Institute of Science for teachers intendine to teach this course. These included (a) a one dav conference on the chemical industry in general, with lectures from experts in many fields, (h) eight lectures by chemists from some of the major chemical industries and visits to some of these industries, such as the Dead Sea potash and bromine works and to the heavy chemical industries (ammonia, nitrates, detergents, plastics) round Haifa bay, and (c) a four day in-service training course, specifically designed for teachers of the new unit. In the training course, each case study was discussed in depth, the experiments were tested in the lab, and various administrative and didactic problems were discussed. During the preparation of this course, contacts were estabS lished with many of the local industries which helped to proE vide some financial support and in organizing visits.
C Application to Other Curricula 0 In all countries there is a need to open a window to the "real N world" outside the school. We feel that the chemical industry A R
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can provide an interesting and useful vehicle for introducing relevant issues to pupils in senior high schools. The guidelines in planning such a course are the same in most countries, even though obviously the actual industries described and the details of the methods of production vary from place to place. Each case study should be chosen using the criteria described above, keeping in mind the importance of that particular industry to the country in question. Other interesting case studies are petrochemicals, pharmaceuticals, explosives, dyes, and food additives. These, however, require a more extensive knowledge of organic chemistry. I t is important to limit the number of case studies to three or four and to suggest the others as options, or to incorporate one as part of the existing curriculum. In some countries it might not be possible to add a full course to the existing curriculum. This is the merit of the case studies method, which allows the teacher, or the examining
368 1 Journal of Chemical Education
hoard, to incorporate one or more case studies as a part of the curriculum. For example, a case study written with this idea in mind, is the "Fertilizers and Chemicals Limited" story (15). This case study, which was written for those not specializing in chemistry, describes mainly the basic principles and processes used in the production of ammonia and nitrogen fertilizers. I t includes also problems of the availability of raw materials, the location of the plant, ecological problems, etc. It is taught as a summary of the energy, kinetics, and equilibrium aspects of the chemistry curriculum and gives an insight into the applications of chemical concepts to industrial processes. Though the chemical industry in different countries is based on different raw materials, an interdisciplinary approach can he used to enable the student to understand the overall concept of the industrial endeavor, to combine chemical principles with problems of technology and economics and to foster a positive attitude to the preservation of the environment. Literature Cited (11 Prestf 0. M.. Education in Chmzisfry. 1.66 (19701. (2) Elsbernd, H.,andGreen,A.. J.CHEM.EDUC.54.7(19771. (31 Rutherford, L a n d Gardner, M. "Now Trendsin Integratedseienrr Teaching: Val. 1,UNESC0,Paris. 1911.p. 47. ( 4 ) Walker, M., and Daniels. 0.3.. "1"duetrialHoreonbththLaafiin of an Oil Retimry: Bath University Press, 1914. (5) N. Nae, "The Chemical Industry in Israel: Weizmsnn Institute ofscience. 1918 (in
Hebrew).
(6) Ben-Zvi, R.,sndSamuel, D.."RepartNo.4ontheprojxtforHigh School Chemistry ~nIsrael: Weizmann lnatitute of Science, 1916. (I) a Lippincott. W . L., J.CHEM.EDUC. 15,149 (19681.b.Hil1.B.W., J. CHEM.EDUC. r, -,.-,,\.".",. ,"X,,O"C,
(8) a. Tomkins, R. P. T..and Moore. J. A., J. CHEM. EDUC. 52,334 (19751,b. Miller. T. L., J. CHEM. EDUC. 54.502 (19771. (9) a. Kennedy, J. P., C h m Tech. 4, I56 (19141. b. Wittmff, H.,Ch.m.Teeh. 1,754 ,8977, ,- - . . , (101 Ben-Zui. R.,and Hofatein. A , "Report on teacher Veining,"Weizmann lnstitnte of Science, I975 (in (Hebrew). (111 Hofstein. A,. Mand1er.V. Ben-Zvi, R.,and Samuel, D..Europoon JourmlofSchnee Education, in p m , 1979. (12) Peraro, P.. M m r , E.. Samuel, D.. and Ben-Zvi, N.. J. CHEM. EDUC. 55. 383
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(1978).
(13) Young, R. B.,Tiedemann. A. F..Marianomki,L.G.,end Camsra. E. H.,"Pcoduction ofMethaneU~ingOff8horeWind Energv: Final Reportf0rfheU.S.NetionalSEi~nes Foundation, 1915. (141 Hughes, W., "Chemistry Purevemus Applid"inD.J.Daniels.(Editor1"New Movemenfe in the Study end Teaching of Chemistry: Temple Smith. London, 1975,p.
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(15) Hofatein, A,. "FutureTcendn in Integrated Scknco Teaching: UNESCO, Park, Volume 5, 1919,in prens.
