Chemical Education Today
Letters Thermodynamics and Spontaneity A recent article in this Journal (1) advocated eliminating the word “spontaneous” (along with “spontaneously” and “spontaneity”) from the chemical lexicon. The author was of the opinion that these words lead to confusion rather than clarification. I disagree with both the opinion and the proposal, and I believe that the author’s premises are refutable. One premise is, “The dictionary definitions do not fit the strict chemical definition.” It is true that one cannot substitute a dictionary definition in a statement regarding the thermodynamic spontaneity of a process and obtain a sensible statement. But if this were adequate justification for not using a word in a technical sense, we would have to do without the words “work”, “element”, and “equilibrium”, to name just a few examples. All these have specific technical usages, which for the most part do not correspond to their use in general speech. A second premise is, “It is commonly used without definition and its meaning varies among authors using it.” Examples are given of usage which is indeed careless and/or incorrect. I have two responses to this. First, to the extent that it is true, it reflects a failure on the part of the responsible authors to understand and use the terms correctly. Second, twelve physical chemistry and chemical thermodynamics texts which I surveyed from my own bookshelf are unambiguous and consistent in defining and using these terms: ∆Stotal > 0 implies spontaneity. One text uses the term “irreversible” instead of spontaneous in this context. Since these authoritative writers agree, perhaps the remedy is for the malfeasant authors to review some thermodynamics. Beyond the fact that its premises are flawed, the article contains particular statements that are erroneous or misleading. Several examples are cited of statements in which the elimination of the offending term would, in the author’s opinion, clarify the statement. One is “The free energy change is negative—the process will occur spontaneously.” Eliminating the word “spontaneously” from this sentence most emphatically does not clarify it. The result is certainly not a correct statement: “The free energy change is negative—the process will occur.”
To quote from one of the chemical thermodynamics texts (2), “The YES! of thermodynamics is actually maybe.” To say that something will occur is to make a statement of certainty. Thermodynamics can say with certainty what will not happen, but not what will happen. The sentence may be misunderstood even when “spontaneous” is retained, but with its inclusion the reader is at least alerted to the fact that only thermodynamic factors have been considered. Again: “…we may be interested in a criterion for determining the feasibility of a spontaneous transformation…”. While this could have been worded better (…we may be interested in a criterion for a spontaneous transformation…), eliminating the word “spontaneous” from the given statement does not clarify the meaning, since “feasibility” implies practical possibility, which requires both the “maybe” of thermodynamics and a “yes” from kinetics. The article questions the need for a criterion for spontaneity. Since spontaneity equals thermodynamic possibility, this is puzzling. Certainly, whether a process is possible or impossible is of great interest. It would seem what is necessary is to clearly understand the terminology. I contend that striving for such understanding is preferable to abandoning the usage. Given that some confusion does exist, I suggest that the usage “thermodynamically spontaneous” or “thermodynamic spontaneity” would go far toward eliminating it. The term “exergonic” is suggested in lieu of “spontaneous.” I see no objection to using this term as it is defined (∆Gsys < 0); under the constraints of constant temperature and pressure, an exergonic process is thermodynamically possible. It will take some time to bring this term into general usage. It does not appear in the indexes of most texts. And it cannot be used as a general replacement, since it applies only to processes at constant temperature and pressure, the conditions under which ∆Gsys provides a criterion of spontaneity and equilibrium. Despite my objection to this article’s conclusions, and the fact that it contains several questionable statements, I recognize that some confusion surrounds the terms which are at issue. But is this not the nature of the learning process?
Corrections JCE Software Abstract of Techniques in Organic Chemistry, Part 1 The abstract of JCE Software Special Issue 20, Techniques in Organic Chemistry, Part 1 Videotape that appeared in the March, 1998 (Volume 75, Number 3) issue of the Journal omitted appropriate credit for the French version of the videotape. Karine Auclair of the Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada should have been listed as coauthor and coproducer with Lois M. Browne of the French version. The following acknowledgments were omitted: Talent: Karine Auclair and Shirley A. Wacowich, Script and Narration (French): Karine Auclair. We regret these errors.
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Anniversaries 1998 In the January issue of J. Chem. Educ. on page 23, Paul F. Schatz presents some very interesting information about this year’s chemical anniversaries in an article entitled “Anniversaries 1998”. He was incorrect about one point, however. Howard Walter Florey was an “Australian pathologist” not an “English pathologist”, although Florey spent a considerable portion of his life in England. Florey’s life will be a major theme for Australian Historians of Science in 1998. W. P. Palmer Faculty of Education Northern Territory University Darwin, NT 0909 Australia
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Everything we learn involves confusion at some point. Eliminating this confusion is the key to learning, and as such the responsibility of educators. Modifying the terms as I suggest above, so their use would be understood explicitly in the context of thermodynamics, may provide some progress. Literature Cited 1. Ochs, R. S. J. Chem. Educ. 1996, 73, 952–954. 2. Rock, Peter A. Chemical Thermodynamics; University Science Books: Mill Valley, CA, 1983; p 326 Boyd L. Earl Department of Chemistry University of Nevada, Las Vegas Las Vegas, NV 89154-4003
The author replies: Earl writes not only to defend the use of the word spontaneous, but also to correct perceived errors in my article. It is true that a negative free energy change only indicates possible reaction occurrence and not a certainty. This misstep is unlikely to confuse the readers of this Journal; the key question is, how can spontaneous be supported as a term for teaching thermodynamics? The argument that standard dictionaries are poor sources because other scientific terms have common meanings ignores the point that spontaneous, unlike the others, is used without definition. Moreover, I examined historical and standard literature meanings and found this word was rich in nuance,
but ambiguous for the purpose of thermodynamics. The assertion that 12 texts are completely clear in their use of spontaneous is specious. We are not told what these texts are, or their definition of allowed reaction change. The sources I cited are certainly authoritative and yet contradictory in their use of the word spontaneous. The seductive power of the word spontaneous and its unquestioned acceptance as part of the fabric of thermodynamics was the focus of my article. This rebutting author actually helps make my point. For example, he is puzzled as to why anyone would even consider jettisoning the word “since spontaneity equals thermodynamic possibility”. I very much doubt that any of his 12 sources defined spontaneity in this way. The word is liquid, taking on the definition that fits the mind of the chemist, serving neither good science nor good teaching. Finally, Earl hedges his bet. After asserting that no confusion exists, he offers a solution to cure “confusion [that] does exist”: he suggests the phrase “thermodynamically spontaneous” or “thermodynamic spontaneity”. The modifier does not define or clarify the term, however. Thermodynamics remains one of the most difficult subjects for students to understand. Spontaneous is historical baggage; I suggest we stop carrying it. Raymond S. Ochs Department of Pharmaceutical Sciences St. John’s University Jamaica, NY 11439
Letters continued on page 691
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Letters Letters continued from page 659
The ChemCom Curriculum It is curious to me that a college would receive requests to evaluate whether or not Science-Technology-Society (STS) or ChemCom courses are acceptable to meet entrance requirements for traditional college chemistry courses for science and engineering majors (Sanger, M. J.; Greenbowe, T. J. J. Chem. Educ. 1996, 73, 532–536). Why these courses which have shown tremendous successes at the high school level? Being a high school chemistry teacher who has taught chemistry for 11 years, including the ChemCom curriculum for the last four years, I would like to comment on some of my experiences with the ChemCom curriculum versus the traditional curriculum. I have observed that many traditional chemistry courses at the high school level are boring and irrelevant to students and teachers alike. I and my students suffered throughout the years I taught the traditional curriculum. I have further observed that many of the critics of the ChemCom curriculum have not taught the course and, therefore, have not personally experienced its different approach to the teaching of chemistry. I believe teachers who use ChemCom as a course for low-ability students may unfortunately be “dumbing down” the course, much as traditional chemistry courses are also often “dumbed down” for low-ability students. I also believe that college instructors Michael J. Sanger and Thomas J. Greenbowe who have, in their article, expressed several doubts about the ChemCom curriculum, have limited experience with the true nature and depth of the ChemCom course. When both high schools and colleges are graduating students who cannot apply the science they learn to problems that affect our environment, something is seriously wrong with the way our educational systems teach science. The ChemCom curriculum is an attempt to correct this problem at the high school level. The universities must follow suit. At my school I strongly discourage low-ability students from enrolling in ChemCom. I also recommend the course for students who want to major in chemistry or other sciences in college, as well as for students who want to pursue other fields of study. The ChemCom course, in my opinion, produces better thinkers and problem solvers, and more students who remember the chemistry they learned after they leave the classroom. I disagree with Sanger and Greenbowe’s comment that ChemCom “covers a fraction of the content covered in the traditional chemistry courses and has drastically reduced the mathematics and physical chemistry content presented to the students.” I believe this is a case of where the total is greater than the sum of its parts. In my experience, ChemCom students are better with using math to solve chemistry problems than traditional chemistry students. For example, it is my experience that ChemCom students are much better at balancing equations than traditional chemistry students. I believe this is because the ChemCom curriculum heavily emphasizes the meaning behind balancing equations, and it continually revisits the concepts of balancing equations throughout the year. In the same way, ChemCom students, from my experience, are better at solving “ratio problems” or problems that can be solved using dimensional analysis. I urge Sanger and Greenbowe to really spend some time reading the ChemCom curriculum and to observe
and participate in the teaching of it. ChemCom contains a tremendous amount of content. I rarely supplement the ChemCom curriculum. I believe there is no point in heavily emphasizing physical chemistry at the high school level when students rapidly forget most of it as soon as the course ends and it is retaught in first-year chemistry classes in college. The ChemCom curriculum produces students who are thinkers and problem solvers, not students who can crank out meaningless algorithmic solutions to physical chemistry problems. ChemCom has a proven track record of almost ten years of success at the high school level. Compare this to any other recent effort of science education reform at the high school level. Few, if any, can match its long success rate. It is the colleges and universities who now must change, and that is the problem that Sanger and Greenbowe need to address. Carole Magnusson Sacramento High School Sacramento, CA 95817
The authors reply: We hoped our article (1) would promote a dialog between high school and college instructors regarding ChemCom and STS courses. We were pleased that Carole Magnusson took the time to respond to this article. It sounds as if her students who enter college and take general chemistry for science and engineering majors are successful and we would appreciate having her students enroll in our universities. However, we have direct experience here in Iowa with students who have had an STS or ChemCom course taught by teachers who may not be as experienced or talented as Magnusson. Some of our students who have had ChemCom are successful in college general chemistry for science and engineering majors, but most are not. We have heard similar reports from other colleges and universities throughout the Midwest. Other college chemistry faculty are also being asked to evaluate ChemCom courses and they face the same issues that we raised. As suggested in our article, instructors and researchers need specific information about the factors that govern success of students using ChemCom. We thought our article provided a good narrative of the strengths and weaknesses of STS or ChemCom with respect to students that have subsequently enrolled in a traditional college chemistry course. We hope the majority of readers of our article viewed it as a critique and not as an overall attack on ChemCom. Perhaps the larger issue here, however, is that most of the successes attributed to ChemCom are largely anecdotal. In 1996, we were able to find only two empirical studies regarding the effectiveness of ChemCom and the results were not tremendous. Mason (2) tracked ChemCom and traditional students enrolled in a liberal arts general chemistry course. The results indicated that the ChemCom students did just as well as the traditional students. Magnusson reports several anecdotes regarding the successes of ChemCom in her classrooms; we would like to encourage her to report qualitative or quantitative evidence regarding these successes so that others may use and benefit from this information. If her students are never bored with the ChemCom course and if most of these students are successful in a college general chemistry course for science and engineering majors, then this information is worth sharing. It is unfortunate that Magnusson does not extend this same cour-
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Letters tesy to instructors at the high school and college level who choose to teach a traditional course and do so with a reasonable degree of success, even making the course interesting to the majority of their students. At the 210th ACS national meeting in Chicago, we attended a symposium chaired by Diane Bunce (3), in which she and several high school teachers analyzed the effectiveness of teaching high school chemistry courses using the macroscopic, microscopic, and symbolic levels of representation and assessed conceptual understanding. One teacher (4) compared the performance of students previously taught using ChemCom or traditional methods, and the results demonstrated that the ChemCom students did not perform as well as the students taught using traditional methods. These results, and the implication that instruction involving ChemCom was not as effective as traditional methods, led to a spontaneous, heated, and highly emotional debate. The proponents of ChemCom appear to be very loyal and protective about their courses. We hope that high school and college chemistry instructors will continue to collaborate and improve the teaching and learning of chemistry at all levels. Magnusson takes issue with our statement that “ChemCom covers a fraction of the content and covers less mathematics and physical chemistry content than traditional chemistry courses.” This statement was reported by the publishers of ChemCom (5). Magnusson uses this statement in an attempt to say we are arguing for incorporating more physical chemistry in the high school or introductory college chemistry course. This is not what we had intended to convey to the reader. The publishers of ChemCom recommended it as an appropriate alternative to the traditional chemistry course only for those students who do not intend to pursue a career in the scientific fields (5), and these students tend to be lower-ability chemistry students. We had the opportunity to talk with a group of ChemCom teachers at the 14th Biennial Conference on Chemical Education at Clemson University. These teachers told us they would not recommend that their ChemCom course serve as a prerequisite for a traditional college science and engineering general chemistry course. They also indicated that they tend to have low ability students in their classes and that this is the type of students who benefit most from this course. This is in direct contrast to the student population that Magnusson teaches. This leads to one of the problems we addressed in our article. What is reasonable for one teacher or school system may not be reasonable for others. How then do college admissions officers evaluate the course on a high school transcript entitled “Chemistry”? It is not unusual for college and university faculty to be asked by a high school teacher or a college admissions office to evaluate high school courses. School systems want to know if their courses count as a college prerequisites. With many schools adopting block scheduling, developing integrated courses that spread out over two or three years, and sending student portfolios rather than grades, it becomes difficult for admissions officers to evaluate whether or not a high school chemistry course provides the traditional prerequisites skills and knowledge identified by college chemistry instructors. When a high school transcript shows a course designated as Algebra I and II or Chemistry I and II, admissions officers are no longer sure what these courses represent. Ten years ago, they did. Recently, Iowa's three public universities have held a series of meetings to address these 692
issues (6). New high school curricula typically face college scrutiny: first to determine whether the content includes material deemed necessary for success in a particular course, and second to determine if it has a good chance of being as effective as courses previously accepted as a prerequisite. One of the purposes of our provocative opinion was to bring attention to the possible difficulties ChemCom students may or may not experience when enrolled in traditional college chemistry courses that tend to be competitive and focus on algorithmic problem-solving abilities. Please note that this is not our choice of how a course should be structured, nor does it reflect how we teach our own courses. What we described was the status of most introductory college chemistry courses that ChemCom students will face. Magnusson has suggested that college and university instructors should change the way they teach chemistry, perhaps to reflect the ideals of ChemCom. Chemists continue to define the subject of chemistry as an empirical science, and not as social science. We discussed some of the weaknesses of college chemistry courses. We acknowledge that college chemistry instructors can be doing a better job, but let’s agree that many students who have had a traditional college chemistry curricula are successful. Most college chemistry instructors include a heavy dose of numerical problem solving in their courses. It is this ability to work numerical problems that is most valued by potential employers. We agree with Magnusson that curriculum changes are in order for college chemistry courses. We are working locally with our Iowa colleagues to improve the college general chemistry curricula. However, even within our own departments, these curriculum changes are resisted. ChemCom is a popular curriculum, and we would rather have high school students take a ChemCom course than no chemistry course. But the fact remains that more research is needed to support the statement that ChemCom is tremendously successful. It is our opinion that ChemCom serves as a viable and effective course for students who do not plan to enroll in college. It may or may not serve as an effective college admissions course, especially for science and engineering majors. If it can be shown that STS and ChemCom effectively prepares students who plan to major in science or engineering, we will wholeheartedly support ChemCom. We are open to debate these points, to participate in research studies about ChemCom, and to visit ChemCom classrooms. We welcome the opportunity to receive additional information that would change our opinion. Perhaps a symposium at a national ACS meeting about the successes that STS and ChemCom students enjoy when they take college chemistry courses is in order. If so, we invite Carole Magnusson to serve as co-chair.
Literature Cited 1. Sanger, M.; Greenbowe, T. J. Chem. Educ. 1996, 73, 532–536. 2. Mason, D. “Life after ChemCom: Do they succeed in universitylevel chemistry courses.” Presented at the annual meeting of the National Association for Research in Science Teaching, April, 1996. 3. Bunce, D., Chair. “Classroom Teacher as Researcher: A UniversityHigh School Collaborative Effort.” Presented at the 210th Annual National Meeting of the American Chemical Society, Chicago, IL. 4. Klazer, T. “A Comparative Study of Learning and Achievement Between ChemCom and Traditionally Taught Chemistry Students.” Presented at the 210th Annual National Meeting of the American Chemical Society, Chicago, IL.
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Chemical Education Today
5. Kendall/Hunt Publishing Company. Textbook Series Brief for ChemCom: Chemistry in the Community, 2nd Edition. 6. Barron, M. “RCER Task Force on Applied High School Academics and Other Reformed Curricula.” State-Wide Meetings of the Iowa Regents Universities. February, 1997, University of Northern Iowa, Cedar Falls, IA; April, 1997, Iowa State University, Ames, IA. Thomas J. Greenbowe Iowa State University Ames, IA 50011-3111 Michael J. Sanger University of Northern Iowa Cedar Falls, IA 50614-0423
The reply to the authors: One of the ways to measure the successes of the ChemCom curriculum is by enrollment figures. For Sacramento High School, these figures are shown below. Our chemistry classes average 32 students each. Our chemistry student population has doubled since I began teaching ChemCom five years ago. Number of Chemistry Classes at Sacramento High School 1991–1997 Academic Year
Number of ChemCom Classes
Number of Traditional Classes
Approximate Number of Chemistry Students
1991/92
0
4
128
1992/93
0
4
128
1993/94
2
4
192
1994/95
3
4
224
1995/96
4
3
224
1996/97
4
3
224
1997/98
5
3
256
Hopefully, this increase in students is reflected (by an increase) in the college chemistry population. Greenbowe and Sanger’s article says this is so. And are not increases in college chemistry enrollment a major purpose for high school chemistry classes as seen by Greenbowe and Sanger? Greenbowe and Sanger further state that 20–35% of students enrolled in introductory college chemistry fail it, and that nearly all of these students have had a traditional high school chemistry course. Using some hypothetical numbers and Greenbowe and Sanger’s percentages, let us explore how giving only percentages may not show a true picture. Assume a college has 400 traditional chemistry students in a particular year. In this year, a maximum of 140 students would fail (35%). Now say that same college next year gets 25% more chemistry students, all of them former ChemCom students. Now the college has 500 first-year chemistry students. Again 35% of the traditional students fail. Now, suppose by saying “most ChemCom students do not pass general chemistry”, Greenbowe and Sanger meant half way between 50% and 100% or 75%, so only 25 of the 100 former ChemCom students will pass the general chemistry course. So now the failing percentage has risen from 35% to 43%. However, the number of students passing chemistry has increased from 260 to 285. I believe this increase is what is most important. Of course, real data needs to be collected in this area, but the point is valid.
Greenbowe and Sanger state that the ability to work numerical problems is what is most valued by potential employers. From what I have read, being able to work in a team and being able to creatively problem solve are skills much more valued by employers than number crunching. In fact, much numerical problem solving can be taught on the job. Just because a ChemCom student does not get a “heavy dose of numerical problem solving” doesn’t mean the ChemCom student is lacking in this area. I believe it is the quality and not the quantity of numerical problem solving techniques that makes a student succeed in this area. And as I explained in my first letter, ChemCom does an excellent job of revisiting topics to help a student understand mathematical problem solving. I wonder how many teachers use the ChemCom curriculum for low-ability students. I strongly emphasize to my students that to be successful in ChemCom, they must have already passed Algebra I with at least a “C”. My students are not low-ability students. Any course’s standards can be lowered to accommodate low-ability students. Perhaps I am one of the few teachers who believes ChemCom is not for low-ability students. Although I advertise to prospective students that ChemCom is a college prep course, I agree with Greenbowe and Sanger that ChemCom is an effective course for non college bound students, because many non college bound students are not low-ability students. I also agree with Greenbowe and Sanger that more data about student success in chemistry needs to be collected and shared. Are the current science and engineering programs at colleges and universities meeting employer’s needs for productive workers? Do most science and engineering majors upon graduation have enough of the right kinds of skills to get a job that is worthy of their four years of college education? Do most science and engineering majors become scientists and engineers? If the answers to all of these questions are yes, why are curriculum changes in order for college chemistry courses? If the answer to one or more of these questions is no, why are curriculum changes at the college level resisted? We first need to address the issue: Is there a mismatch between the college science and engineering curricula and the job market for graduates? Then we can validly address the issue of a mismatch between ChemCom and college chemistry courses. In addition, these more difficult questions need to be researched: Are college chemistry curricula discouraging or encouraging student success? Is the 20–35% failure rate of students truly mainly the fault of the high school teacher, as Greenbowe and Sanger say these failing students themselves suggest? In addition to being good algorithmic problem solvers, can most successful college chemistry students also apply their knowledge to real life issues? It is my opinion that colleges like Iowa State University need to analyze their own chemistry curricula first. College chemistry courses are clearly in a state of transition. For example, how has Iowa State University’s college chemistry curriculum changed, and what are their future goals for their chemistry course? Perhaps it may be best for them not to discourage any students from enrolling in their college chemistry for science and engineering majors until they figure out exactly where their reform efforts are headed. Carole Magnusson Sacramento High School Sacramento, CA 95817
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