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Development of a first-year chemistry course with emphasis on environmental chemistry.

On its present course, freshman chemistry is on its way to becoming a dead subject, "like Latin"

I am going to discuss the development of a new, first-year program in environmental chemistry at the University of Guelph. I have taught and/or coordinated freshman chemistry for over 15 years. Lately, I have become increasingly uninspired by the curriculum. Let me review my reasons with you briefly.

* First, the curriculum is dated. Very little in the typical freshman curriculum belongs to the second half of this century. We chemists are making introductory chemistry a dead subject, like Latin, and leaving to other disciplines the exciting new developments in chemical and molecular science such as biochemistry, materials science, and toxicology.

* Second, the curriculum is overly oriented towards chemical principles: the "Chem Study" approach. Principles are difficult to appreciate without a knowledge of fact upon which to hang them. The introductory student lacks a substantial corpus of facts and, as Ron Gillespie, FCIC, said 15 years ago, the chemistry curriculum changed in the late '60s from an uncomprehending regurgitation of fact to an equally uncomprehending regurgitation of theory. What we need is some appropriate blend of fact and theory; and appropriate does not mean to me a familiarity with the physical and chemical properties of the chlorides or hydrides of all the elements.

* Finally, the curriculum does not reflect what chemistry is all about today. On the one hand, my first point, it does not reflect what today's practising chemists actually do. How many of us as professional chemists and researchers actually use day by day the principles we strive so diligently to impart to our students? On the other hand, our curriculum fails to answer the questions our students might have about chemistry -- the things they read about in newspapers or see on TV.

Let us pretend to be students who have just completed first year. We return home to our families, prepared to enlighten them on the science behind the issues of the day. Do we understand stratospheric ozone depletion? No, probably the only things we learned about ozone are that it is an endothermic substance and that its structure is non-linear.

What do we know about acid rain or transboundary pollution? Not much; our study of acids and bases had an almost neurotic fixation with acetic acid.

Do we know what a part per billion is? No, we did all our calculations in moles per litre. I once spoke at a meeting where I tried to make the point that our students would have to know about the units used in newspaper articles in order to understand environmental issues. Quite clearly I failed to make this point, because the question period was largely consumed by a high school teacher in the audience who disagreed with me completely. He argued that ppm and ppb would confuse the students, and so we should always use the chemists' units of moles per litre! How then should we describe the extent of lead contamination at the site of a disused secondary lead smelter?

What I am trying to say is that environmental issues are an important part of what chemistry is all about in the news media. If we ignore these issues in our classrooms, it's no wonder that our discipline is perceived by students as uninteresting and irrelevant. Furthermore, we tacitly leave the students to gain their information about them from nonchemical professionals (e.g., in their biology classes, from environmental activist groups who may not cover the issue from all perspectives, or from news media journalists, who are not usually scientists).

Remember too, that very few of the students in that first-year class will go on to become chemists. This is the only chance we have to tell them what chemistry is all about and how it affects their lives. I feel that students will be more likely to feel personal involvement with issues that they know something about and care about. Don't expect a sympathetic view of chemists and of chemistry if the leaders of the next generation -- politicians, journalists, taxpayers -- found our discipline boring and irrelevant when they studied freshman chem.

If I could take a moment to reminisce, my own introduction to chemistry in the 1950's was very relevant to what was then interesting - new plastics, detergents, miracle crease resistant fibres. Chemistry was clearly interesting and alive, and I was quickly hooked. Quite obviously, we can't turn back the clock and talk about what interested people in the past. That's why I believe that the environment, and its relationship with industrial processes, should feature prominently in our university programs today.

In this respect, the high school programs -- at least in Ontario -- are making more of an effort than we are in the universities; a full 20% of the final year chemistry curriculum is mandated to be spent addressing societal issues.

You may counter an appeal to include environmental issues in the freshman program by saying that our discipline already has a negative image, and that we do not need to reinforce it. In my opinion, it's quite the contrary. Chemical innovation can solve environmental problems or reduce their effect.

Consider the issue of mercury pollution from chlor-alkali plants. This was the top environmental issue in 1970. We never hear about it today. Why? Because of the development of mercury-free, membrane cells for the electrolysis of brine. What about the enormous research efforts going on internationally to find replacement substances for the CFCs which are to be phased out under the terms of the Montreal Protocol?

Closer to home, Canadian technology is involved in the complete redesign of Inco's smelting operation at Sudbury, Ont., so as to meet the 1994 targets for reduced emission of acidic gases, at a cost of almost $500 million. Union Carbide Canada has developed the Can-Solv process for reducing acidic emissions from coal burning power plants. Chemists and chemistry can be the agents for providing the answers to environmental problems, not the cause of the problems. There are thus, in the 1990s and beyond, satisfying, challenging, and societally useful careers to be had in our discipline.

Responding to the call for action

A particular problem for us as teachers and designers of first year chemistry courses is that chemistry specialists are in the minority in freshman class. We can't teach the course as though it were directed only at chemistry majors, otherwise we short change the "service" students, and reinforce the alienation of these people towards chemistry. Equally, we can't just cater to the service students, or we short change the chemistry majors. In my opinion, this leaves us with a very important issue to address regarding curriculum; it must be relevant and interesting to all students, and at the same time presented in appropriate depth to provide a professional foundation for future chemists. This is where I believe that a suitable mix of chemical principles and practical (not just descriptive) chemistry can fill the bill.

However, I believe that the idea I have just outlined can give us insight as to what to leave out of today's overcrowded curriculum. If the service students don't need a topic, perhaps the chemists should take it later, in their specialized courses.

Like many other universities, the University of Guelph has recently instituted a new program in environmental science. We are trying to make this new environmental program something really new, and not just a repackaging of existing courses. To that end, we in the Department of Chemistry and Biochemistry are putting together a new first-year program in chemistry, designed for the environmental science students. As the students progress through the program we shall be providing a second-year course in inorganic/organic descriptive chemistry and a fourth-year course in industrial chemistry. My own responsibility is to develop the first-year program.

The first job has been to define what should be included in the curriculum and, equally, what should be omitted. The intention is very definitely that this pair of courses should not be perceived as a soft option in comparison with the regular first-year chemistry program. Therefore, it was decided right away that there should be a strong emphasis on the quantitative aspects of chemistry; this is not intended to be a course where we simply wring our hands about environmental pollution. The following seemed to be the "must have" topics in a first year program, whether environmentally focused or not: stoichiometry; energetics; kinetics; electrochemistry; equilibria.

You really cannot discuss any chemical problem without stoichiometry. You have to know what processes are energetically possible, and that means getting as far as the second law of thermodynamics. In addition, the importance of sunlight in the environment means that the energetics of photochemical reactions must be addressed. Once you know what chemical processes are possible, you have to know which ones proceed at measurable rates. Finally, electrochemical processes, and gaseous, aqueous, and heterogeneous equilibria include a wide variety of practically important issues.

Having defined some valuable chemical tools which could be used in the new program, it was necessary to decide what environmental issues should be included in the context of the principles just mentioned. Clearly such a list is subjective, but here are some possibilities:

Atmospheric processes: For example, greenhouse effect, stratospheric ozone depletion, acid precipitation, and ground level ozone. These topics are attractive because they involve small molecules with many of which the students are already familiar (NO, |No.sub.2~, S|O.sub.2~, etc.)

Aqueous processes: For example, water quality, (dissolved oxygen, alkalinity and hardness of natural waters), buffering, drinking water treatment, and acid mine drainage.

Electrochemical processes: For example, chlor-alkali process; production of electropositive metals; corrosion; batteries; electroplating; electrolysis of water and a "hydrogen economy".

Having determined what we would like to include in the new program, it was now necessary to decide what" traditional" topics to omit. The following topics in the conventional first year curriculum seemed less appropriate for the client group: Electronic and molecular structure; Transition metal chemistry; Balancing redox equations; Organic chemistry.

Frankly, there seems to me to be little justification for teaching electronic and molecular structure in first year. In Ontario, we teach this at just about the same sort of level as the students have already encountered in their high school program. Non-chemists will never use it again: the molecular geometry of S|F.sub.4~ and the electronic structure of |Cr.sub.2+~ (g) are of no conceivable interest to an environmentalist, or for that matter scientists such as microbiologists or nutritional scientists.

Chemistry specialists can meet this material in later years, and cover it at a higher level. All that is absolutely needed is some knowledge of the difference between ionic and covalent bonding. Similarly, nonspecialists will likely not refer to transition metal chemistry or redox equations again, and chemists will be exposed to them later in much more detail. I feel that a guiding principle for the first year curriculum should be that topics needed only by chemistry majors should be deferred to later, more specialized courses.

I decided to omit all reference to organic compounds, except in two contexts: combustion of fuels and chlorofluorocarbons. This meant that topics such as pesticides, PCBs, dioxins etc. could not appear in the first-year program, but would have to be deferred to a later course on descriptive inorganic/organic chemistry.

Here is an outline of the new program, which covers a full academic year. Although some of these chapter headings look like "descriptive chemistry"and others" chemical principles", the goal is that even the more descriptive material should have a quantitative slant. Also, the reactions that are discussed in the "descriptive" chapters are also used to exemplify the chemical principles in the more traditional chapters. Nevertheless, I believe that most of the material discussed here would be appropriate to any first-year program, and not just one directed towards environmental science students.

Introduction: Compartments of the environment, reservoirs, residence times; nomenclature of inorganic compounds (review); Ionic vs. covalent bonds (review); How to do chemistry problems; unit cancellation and significant figures (review).

Stoichiometry: Mole concept, simplest and molecular formula; concentration, including units of ppm, ppb, etc; dilutions; chemical equations; mass/mole calculations, with emphasis on very large and small quantities; sequential reactions; limiting reactant; percent yield; stoichiometry in solution; chemical analysis: gravimetric, volumetric, instrumental.

Industrial Processes: Examples of C&E News Top 50 chemicals and how they are made; emphasis at this stage on stoichiometry; examples: |H.sub.2~S|O.sub.4~; HN|O.sub.3~; |H.sub.3~P|O.sub.4~; NaOH and |Cl.sub.2~; N|H.sub.3~; CaO/Ca|(OH).sub.2~.

Energetics I: First law; definition of enthalpy; thermochemical equations: energy changes and stoichiometry; standard enthalpy of formation; bond energy; fuels; photochemical reactions.

Gases and the Atmosphere: Ideal gas equation: pressure vs. concentration; units of ppmv, ppbv, molec |cm.sub.-3~; vapor pressure; partial pressure; composition of the atmosphere; residence times of |O.sub.2~, |N.sub.2~; |H.sub.2~O, C|O.sub.2~ in the atmosphere; infrared absorption; radiatively active gases; global warming.

Gaseous Equilibria: Concept of equilibrium; define |K.sub.p~ and |K.sub.c~; Le Chatelier's principle; equilibrium calculations, including reaction quotient; main examples used: |N.sub.2~/|O.sub.2~/NO; |N.sub.2~/|H.sub.2~/N|H.sub.3~; S|O.sub.2~/|O.sub.2~/S|O.sub.3~; Ni/CO/Ni|(CO).sub.4~.

Kinetics: Rate vs. rate constant; 1st. 2nd, pseudo- 1st order reactions; differential and integrated forms; steady state approximation; steady state vs. equilibrium; rate law and mechanism: elementary reactions; activation energy.

Ground Level Ozone: Formation and reactions of the OH radical; mechanism of oxidation of C|H.sub.4~ in the atmosphere; natural and elevated levels of |O.sub.3~ in the troposphere; conditions for developing photochemical smog; catalytic converters.

Water: Physical properties; natural waters: dissolved solids and irrigation; water hardness; drinking water: purification, common contaminants, fluoridation.

Acids and bases: pH; Bronsted-Lowrey definition; dissociation of weak acids and bases; pH calculations, including common ion effect and buffer solutions; buffering of natural waters; alkalinity.

Heterogeneous equilibria: Gases in water: Henry's Law: |O.sub.2~ and acidity of "clean" rain; ionic solids: solubility rules, |K.sub.sp~ calculations; partition equilibria: extraction; bioconcentration and biomagnification.

Acid precipitation: Sources: coal burning and metal smelting; S|O.sub.x~ vs. N|O.sub.x~; acidity of C|O.sub.2~(aq) vs. S|O.sub.2~(aq); atmospheric oxidation of S.|O.sub.2~; effects of acidic emissions; curbing acidic emissions.

Energetics II: Entropy and free energy: Gibbs-Helmholtz equation; standard free energy of formation; calculating |DELTA~ |G.sup.O~ from tables; |DELTA~ G vs. |DELTA~ |G.sup.O~; |DELTA~ |G.sup.O~ vs. lnK; criterion for equilibrium; standard states.

Stratospheric ozone depletion: |O.sub.3~ in the stratosphere: Chapman mechanism for |O.sub.3~ formation/destruction |O.sub.3~ levels: steady state vs. equilibrium; CFCs: catalytic destruction of |O.sub.3~; Montreal Protocol; CFC replacements.

Electrochemistry: Oxidation/reduction; anode/cathode; galvanic/electrolytic cells; half reactions; Nernst equation; electrolysis; chloralkali process; Hg, Ni/Cd, Pb batteries; electroplating.

Metals and mining: Common extraction techniques; electrochemical series; mining, biological sulfide oxidation, acid mine drainage.

As noted earlier, I believe that most of the material discussed here would be appropriate to any first-year program, and not just one directed towards environmental science students. I feel that our efforts in redesigning our first-year curricula should make them more: interesting; relevant to modern society and to students' backgrounds; topical, yet based on quantitative chemical principles.

I have presented one vision of what one particular first-year program might look like. I'm sure that others will have very different ideas on revitalizing their curricula. I hope that as we approach the 21st century, chemistry will be seen by our students to be alive and kicking, worth studying in its own right, and also the gateway to interesting and worthwhile careers.

Nigel Bunce, FCIC, University of Guelph. This is an edited version of the Union Carbide Award Lecture which Bunce gave at the Canadian Chemical Conference in Edmonton in June.
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Title Annotation:University of Guelph's new chemistry curriculum
Author:Bunce, Nigel
Publication:Canadian Chemical News
Date:Apr 1, 1993
Words:2685
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