J. P. Chesick Haverford College Hoverford, Pennsylvania
I
Intearated Physical-Analytical Course
Until two years ago, the required quantitative analysis and physical chemistry course program for the chemistry major at Haverford College followed a traditional pattern. Quantitative analysis was given as a one-semester course following the general chemistry course with no other prerequisites. Standard exercises in volumetric and gravimetric analysis occupied the laboratory for two afternoons per week, and the two class periods per week were spent in discussing chemical equilibria, titration curves, electrochemistry (starting with the Nernst equation as a postulate), and properties of precipitates and colloidal phenomena. Since no background of physical chemistry could be assumed, i t was difficult to present a high-level course. This course as weU as physics and calculus were the prerequisites for the two-term physical chemistry lecture course which was usually taken in the following year. Physical chemistry laboratory work was presented in a separate course in the spring semester. As a result of these prerequisites and the course structure, the student did not encounter much in the way of rigorous mathematical formulation of chemical problems until his junior or senior year. It may be noted, however, that most &dents who eventually proceed past the introductory chemistry course take calculus in their freshman year or have had previous schooling in calculus. The desire to present more quantitative chemical theory at an early stage in the chemistry program was coupled with the feeling that the work in quantitative analysis could and should be more closely integrated with its applications to all fields of chemistry. This resulted in the revision of the three-term quantitative analysisphysical chemistry lecture course sequence leading to a three-term integrated unit. This was also responsible for the introduction of the one-tenn freshman chemistry offering, described separately by R. I. Walter.' Scrutiny of the contents of the physical chemistry course indicated that although calculus was essential to most of the material, the specific content of the general physics course was required for only certain blocks of material. It was felt, for example, that a rigorous treatment of thermodynamics, a discussion of reaction kinetics, and applications of thermodynamics to various problems could be handled prior to a formal college course in physics. We were not interested in a quick or nonthorough tour through thermodynamics which would have to be repeated in more detail or with more rigor later in the undergraduate program.
See mrs JOURNAL 42,201 (1965).
The new three-tenn physical-analytical curriculum was set up to begin in the second semester so that freshmen who had finished the one-term general course and who also were taking calculus concurrently could begin formal work in physical chemistry in the second term of their first year. Students taking the full-year general course would begin the sequence in the second term of the sophomore year. Conlpletion of the first term calculus course and a t least concurrent enrollment in the second term calculus course were required. Approximately three-quarters of the time in this first course was spent in a careful development of the laws of thermodynamics up through the definition and properties of free energy functions. The chief application considered was the formulation of chemical equilibrium constants. Chapters 1 through 12, excluding chapter 9, of Klotz, "Chemical Thermodynamics" (now available in revised form in paperback) (1) provided the principal text. This book was chosen because of the logical completeness of the presentation with a minimum of extraneous material. Mahan, "Elementary Chemical Thermodynamics" (2) was used as auxiliary material for more verbal and qualitative statements. The two texts were found to be quite complementary. Both were necessary. Particularly vital to the presentation was the period of about a week which was spent discussing exact and inexact differentials and calculus of functions of two or more dependent variables. This material is usually only briefly discussed near the end of elementary calculus courses, and this coverage permitted paying particular attention to materials which would be used in the development of thermodynamics. The last quarter of the semester was spent doing equilibrium prohlems and calculations of titration curves, part of the class material found previously in the quautitative analysis course. A standard text in quantitative analysis provided material for this work as well as the basic reference text for the lab work. The second semester of the sequence is also set up to avoid the requirement of physics as a prerequisite. This term is devoted to chemical kinetics, applications of thermodynamics to ideal and nonideal solutions, phase equilibria, problems in solution and heteiogeneous chemical equilibria, eleetrochen~istryand redox titrations, physical chemistry of polymers, surface and colloid chemistry, and structure of solids and liquids. The core of the lecture work in the traditional quantitative analysis course is discussed as applications of physical chemical principles in the new program. A general physical chemistry text and additional materials from the quantitative analysis text provide the reading materials for this second course, offered in the fall semester. Volume 42, Number 4, April 1965 / 199
If the student has taken or is concurrently taking physics, he may continue with the third course in the sequence in the second semester. Otherwise this course is deferred until the physics requirement is satisfied. This course is devoted to the elements of quantum mechanics with some chemical applications and to a development of statistical mechanics and thermodynamics. laboratory Work
The time allotted to the laboratory work in the old quantitative analysis course is divided up among the first two semesters of the new sequence. I n the one period of 2'/2 to 3 hours per week devoted to course laboratory work, the foUowing experiments are performed : Standardizat,ion of base and determination of weak acid unknown. Colorimetric determination of manganese in unknown steel sample. Speetrophotometric determination of equilibrium constant of farmatiom of thiocyanato iron(II1) complex (5). Preparation of standard thiocyanate and determination of unknown silver nitrate sample by Volhard method. Determination of silver acetate solubility as a function of acetat,e concentration of constant ionic strength and extraction of equilibrium constants from the solubility data for the three equilibria considered (4).
The following experiments comprise the work of the one laboratory per week with the second course in the sequence: Titrimetric determination of the kinetics of the saponification of d h y l acetate. Solubility of benaoic acid as a function of temperature and the det,ermination of distribution between two immiscible vhases. Potentiometric titration of weak acid. Standardization of thiosulfate solution and analvtical determination of equilibrium constant of hydroquinone-silver ion resetion (5). Potentiometric determination of the thermodynemio properion reaction (5). ties of the hydroquinan-ilver Determination of iron in unknown are sample by dichromate t,itration using both an indicat,or and potentiometric endpoint determinations.
The philosophy of the laboratory program has been to attempt to retain enough of the quantitative analysis course work to build and test laboratory technique, e.g., preparation of standards m d determination of unknown samples. It is then desired to use the technique immediately to investigate some chemical system. It is believed that the retention of some of the "simple" unknowns from the quantitative analysis course is necessary because other complications in more elaborate physical chemistry experiments sometimes tend to obscure the shortcomings in the laboratory technique of
the student. The laboratory program is still under development in concert with changes in the elementary laboratory program, hut we feel satisfied with the essential outline of the work. Evaluation
Evaluation of this new course program is quite subjective and bears the stamp of the personal biases of those who are both initiating the changes and are then evaluating the results. The digestion of the material did not seem to be hampered by the early presentation of undiluted physical chemistry. St.udent response seemed favorable and morale appeared high. The interest in the laboratory program was appreciably greater than that observed in the quantitative analysis course. Students of a physical bent were given the opportunity to see a side of chemistry as freshmen which they would not have experienced in the traditional program until their junior or senior years after commitment to chemistry as a major. I n the new program the inorganic chemistry course has been upgraded to senior level with physical chemistry now available as background for the course. These changes, in the context of the whole major program, may be summarized by showing two possible student programs. The three term courses of the integrated physical-analytical sequence are indicated as Phys. Chem. I, 11, and 111. In plan A the student through appropriate performance on the Advanced Placement examination or the local departmental placement examination has been placed in the one tern1 general conrse. I n plan B the student has been placed in the full-year general survey course. The courses indicated for the sophomore and junior years may be taken in any combination provided the physics requirement for Phys. Chem. I11 is satisfied and the physical chemistry courses are taken in sequence. Thus Organic Chemistry and Phys. Chem. I1 and 111may be interchanged in program A if the student desires. Advanced organic courses and the separate physical chemistry laboratory course, centered on the text of Shoemaker and Garland ( 6 ) , may be scheduled to suit the individual student's interests. At least concurrent enrollment in Phys. Chem. I11 is required for the physical chemistry laboratory course. Laboratory project courses would appear in the senior year. Grades of 4 or 5 on the Advanced Placement examination combined with a suitable secondary school course preparation wodd frequently enable the student to omit completely the general chemistry conrse. There is a difficulty with existing programs in other schools which have a, full year honors course for part of the freshman class. Inclusion of a partially complete
Possible Major Course Arrangements
Year Sr. Jr.
1st term Inorganic Organic Chem.
Saph.
Physim Phys. Chem. I1 Fr. Advanced General Chem. Calculus Total student load is five courses per term.
200
/
Journal of Chemical Education
Program B
Program A 2nd term
1st term
2nd term
Comprehensive Exam Organic Chem.
Inorganic Physics Phys. Chem. I1 Organic
Comprehensive Exam Physics Phys. Chem. I11 Organic Phys. Chem. I General Chem. Calculus
Physics Phys. Chem. 111 Phys. Chem. I Calculus
General Chem. Calculus
treatment of thermodynamics (using either the L. K. Nash (7) or B. AIahan (S) paperback introductions to the subject) may result in a group of students from such a course who are appreciably out of step with other students who come from a slower moving traditional full year course. This difference in background becomes apparent when they meet later in the physical chemistry course. Enrollments in courses after the first year level in colleges and universities much larger than Haverford are usually not large enough to justify a continuing division into "regular" and "honors" class sections. We feel that our program helps to prevent boredom and provides for the rapid advancement of the well prepared freshman student without adding a handi-
Robert I. Walter Hoverford Coliege Haverford, Pennsylvania
cap for the student who takes the two-term, elementary course. Literature Cited (1) KLOTZ,I., "Introduction to Chemical Thermodynamics,"
W. Benjamin, Inc., New York, 1964. (2) MAHAN.B. H.. "Elementarv Chemical Thermodvnamics" W Bkiamin. Inc.. New ~ o r k1963. . ( 3 ) RAME&E,R.,J. CHEM.EDDC.40, 71 (1963). (4) A silver acetate solubility study has been mentioned by RAMETTE, R., J. CHEM. Enuc ,37,344 (1960) ( 5 ) LIVINGSTON, R., AND LINGANE, J. J., J. CHEM.EDUC.,15, 320 (1938). (6) SHOEMAKER, D , P., AND GAHLIND, C. W., "Experiments in Physical Chemistry," McGraw Hill Book Co., New York, 1962. (7) NASH,L K , "Elements of ChemicalThermodynamics," Add~son-Wesle~ Publishing Co , Inc , Reading, Mass , 1962
Two-Track Introductory Chemistry
The development of new secondary school programs in chemistry and the other sciences, and the expansion of the advanced placement program have led to substantial improvement in the knowledge and scientific sophistication of many students in the first year college chemistry course. Even students who have not studied one of the new programs have benefited from the general upgrading of secondary school science education which has resulted. These changes have produced serious problems in placement and course structure for the undergraduate college program in chemistry. Provision must now be made for identifying and continuing the training of entering students whose backgrounds range from no chemistry (and sometimes little other science) to the equivalent of two years of college work. The introductory courses now in operation at Haverford College provide a good deal of flexibility in meeting these problems, and may he of interest to other institutions on that account. Haverford is a small liberal arts college for men which is now embarked on a planned expansion to 700 students. The selection process brings us students who generally are able; not all of them are willing, however. Haverford tradition favors a common liberal background for all students, attained in part by a
Presented at the Third Delaware Valley Regional Meeting of the American Chemical Society, Philadelphia, Pa., February 25, 1960, Abstracts p. 15.
rather heavy program of required courses distubuted among the divisions of humanities, social sciences, and natural sciences and inathen~atics. This tradition is opposed to early specialization or over-professionalization of the curriculum. Thus, we need a course plan which will handle students with a wide range of hackgrounds in science, and will contribute at the introductory level to a common liberal background for all students. Larger institutions usually respond to these n~ultiple demands by offering several introductory courses which differ in both pace and content; students are assigned to them according to secondary school background and probable major. Two courses of this sort were offered a t Haverford until seven years ago The best prepared and most interested (because of professional goals) students were assigned to a conventional course in general chen~istry. Poorly prepared students, and those looking for the easiest way to meet the science elective requirement, went into the second course. As a result, students in the latter never observed other members of their classes who were enthusiastic or able, and this experience tended to confirm their preconception of science as uncreative, dull, and unworthy of intellectual effort. The result was an apathetic classroom atmosphere which was difficult for any teacher to overcome, however great his abilities and enthusiasm. This defect of the old system has been eliminated by assignn~entof students to the introductory courses on a new basis, described below. Volume 42, Number 4, April 7 965
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