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860 Journal of Chemical Education • Vol. 75 No. 7 July 1998 • JChemEd.chem.wisc.edu

An Example of a Guided-Inquiry, CollaborativePhysical Chemistry Laboratory Course

Alice A. Deckert* and Lisa P. NestorDepartment of Chemistry, College of Holy Cross, Worcester, MA 01610

Donna DiLulloDepartment of Biology and Chemistry, Springfield College, Springrfield, MA 01109-3797

The last decade has seen fundamental changes in the waychemistry is taught. Many innovative and successful reformsfocus on the first four semesters of college chemistry (1–13).However, relatively few innovations have been reported forthe final four semesters of the chemistry major (14–19). Thesecourses, which generally include physical, analytical, and in-organic chemistry, are also in need of reform (20). Becauseinnovative curricula have been implemented in the first foursemesters of chemical education, students come to expect a highlevel of instrumental and scientific sophistication. If no changesare made to bring at least the same level of sophistication to thefinal four semesters of the curriculum, students who elect tocontinue their study of chemistry may become disillusioned.

We have recently attempted to apply accepted strategies ofguided-inquiry and collaborative learning to a physical chem-istry laboratory course. Our effort builds on the successfulguided-inquiry approach used in many general and organicchemistry courses (1). The goals of this effort were threefold:

1. Guide students toward planning their own experi-ments, independent data analysis, and independentdata interpretation.

2. Increase student preparedness for and intellectual en-gagement in the laboratory investigations.

3. Give students an understanding and appreciation of acollaborative work environment.

The structure of the laboratory course is discussed in thefollowing section. In the remaining sections, student andfaculty comments and suggestions are reported and severalexamples of successful investigations are given.

Structure of the Lab Course

A 12-week semester was divided into four 3-week blocks.Students were divided into lab groups of three to four students.These groups remained the same throughout the semester andfunctioned as a research team. During each of the time blocksteams were charged with answering a specific scientificquestion. Each group elected a principal investigator (PI)whose task was to lead the team effort. The role of PI wasrotated during the semester allowing each member of theteam to be in a leadership role for one investigation.

The laboratory manual provided students with thequestion to be investigated and a list of the chemicals andinstrumentation available to them. Background informationwas provided on theories or experimental techniques thatmight be needed to answer the question. Posted in the labo-ratory were specific instructions on how to operate each

instrument. Using this information, the lab groups wererequired to frame a proposal for how the question could beanswered using available supplies and instrumentation.

Each team was given two 4-hour laboratory periods toobtain the data necessary to answer their question. This re-stricted time frame placed an emphasis on pooling of data andgave students an understanding of the collaborative natureof any scientific investigation. The third 4-hour laboratoryperiod in the 3-week block was used for group analysis andinterpretation of data.

Each lab group met with the instructors to orally presenttheir research proposal sometime prior to the first week ofthe investigation. A written rough draft was handed in at thistime. The instructors suggested any necessary changes andthe final written draft of the proposal was due during thefirst week of the data-gathering phase. Requiring students todevelop and discuss a well-thought-out experimental plan wasdesigned to meet our first and second goals. Not only dostudents come to lab better prepared, they are more likely tobe active participants during the lab. Students retain knowl-edge that is “constructed” (21, 22). By constructing a logicalexperimental procedure and presenting this in the form ofa proposal, students obtain a deeper understanding of theprocess of science.

During the first week of the investigation, the lab in-structors were on hand to answer questions pertaining toinstrumentation. In subsequent weeks, team members whohad hands-on experience with each instrument instructed theother team members on the use of the apparatus. Any ques-tions about technique were directed first to the appropriateteam member. Only after exhausting the team’s resourcescould the instructors be called on to clarify use of an experi-mental apparatus. This required students to “peer teach”. Thislearning strategy has been documented as successful (23, 24 ).

Students were asked to hand in their analyzed data aftereach week of the data-gathering phase. The instructor checkedthe data analyses to ensure that teams were using correctnumbers as a basis for their interpretation of pooled data.This ensured that all team members participated in analyzingthe data and that all data would be correctly analyzed by thethird week of the block. In this way, teams could use the thirdweek of the investigation to compile the data and discuss theirinterpretation rather than to analyze the raw data. Duringdata analysis, peer teaching was again evident. Students whohad performed a particular analysis successfully helpedteam members who had difficulties. In addition, each teamwas able to arrive at meaningful interpretations of their pooleddata with minimal input from the instructors. The goal ofindependence from the instructor in data analysis and datainterpretation was met to a significant degree.

*Corresponding author. Current address: Department of Chem-istry, Allegheny College, Meadville, PA 16335.

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The final requirement was the submission of a paper inthe form of a journal article detailing the investigation. Thehigh level of scientific writing exhibited in the final paperswas a strong indication of the success of this reform effort. Theexperimental sections were well thought out and thorough,without plagiarizing the laboratory manual. In addition, theresults and discussion sections were logical and well written.Each paper clearly benefited from the input and proof read-ing of multiple members of a team.

Assessment of Student Work

Each student received a course grade that representedthe performance of the whole group as well as the perfor-mance of the individual. Each group received a common scorefor experimental design and final dissemination of results.Each student received an individual score for accuracy andprecision of data, participation while in lab, and ability toanalyze data correctly. The group score for experimental designwas based on the oral presentation of the proposal and thefinal written draft. The group was also given a score for thefinal paper. Individual grades were based on the student’slaboratory notebook, observation of the student’s conduct inthe laboratory, and the data analyses collected weekly.

Student and Faculty Response

A questionnaire administered to students after the firstyear of the program revealed two dissatisfactions, which wereaddressed by modifying the course structure in the secondyear. The first criticism expressed by the students was thatteams could not find time outside of class to work on theprojects for the course. The second was that the instructorswere not aware of the performance of individuals and couldnot properly assess individual grades. Two modifications weremade, which strengthened the course while increasing students’satisfaction with their laboratory experience. During the firstyear of the program, students were allowed three laboratoryperiods to collect data and were expected to pool and discussthese data on their own time. Individual data analyses weresubmitted with the final paper rather than on a weekly basis.The first modification was to provide an entire laboratoryperiod for teams to discuss and pool data. This meant thatfewer tasks were performed outside of class, where the in-structor would have no direct knowledge of the performanceof individuals within the group. The second modification wasto require the weekly submission of data analyses. This en-sured that individual students kept up with the data analysisand provided the team with weekly feedback.

The responses to the questionnaire indicate that, in gen-eral, students thought the specific objectives of this reformwere met. Of the 31 students who responded, 55% agreedthat the course had encouraged creativity and 49% thoughtthat independence was encouraged; in both cases, 40% wereneutral. Moreover, 65% of the students felt that they weremore aware of skills and expectations needed to survive in a“real” research environment and 65% said that the experiencehad enhanced their conflict-management skills and enabledthem to work more effectively with others.

Students did not perceive a compromise in the instruc-tors’ ability to provide guidance. Out of 31 responses, 81%indicated that the objectives and expectations were clearthroughout the course. In addition, 81% of students felt that

they received adequate feedback on their performance.The faculty also feel that the specific goals of this re-

form have been met. They unanimously agree that studentscome to lab better prepared and more eager to work. Thisimproved level of preparation among the students increasesthe level of discussion about the experiments during the labo-ratory period. In addition, the availability of expert peerswithin the teams frees the faculty from answering routinequestions and fosters an atmosphere of collaboration and in-dependence. From an instructor’s point of view, this peerteaching was perhaps the most exciting consequence of thereform. Not only were students cementing knowledge byteaching their peers, they were engaged and active partici-pants in each 4-hour laboratory session.

On the surface, this course structure appears to consumemore faculty time than the traditional lab. However, in ourexperience this is not true. The preparation time for eachexperiment is no different than for a traditional laboratory.The biggest differences in time commitment are at the be-ginning of each 3-week block. At the beginning of each block,instructors must meet with each team to discuss specificexperimental plans. This requires some extra time, but theincreased independence of students during the laboratoryperiods that follow makes up for the initial effort. In addition,the work of grading lab reports is reduced to one paper pergroup per investigation. Not only is the quantity of reportsdecreased, the quality is increased to the point that gradingthe final papers is enjoyable.

Sample Investigation

CalorimetryThe question posed to the students was: “What is the

∆Hhyd of sodium acetate and what is the best calorimetricmethod for the determination of ∆Hhyd?” Students had avail-able two bomb calorimeters, a solution calorimeter with asolids sample cell, and a differential scanning calorimeter(DSC). Standards for calibrating each calorimeter were avail-able, along with sodium acetate anhydrous and sodium acetatetrihydrate.

This lab requires students to use thermodynamic cycles,understand the concept of the standard state, and practicethree common calorimetric techniques. In addition, they arerequired to think critically about experimental design andappropriate instrumentation. By comparing and contrastingthe three methods for determining the heat of hydration ofsodium acetate they see first-hand how cumulation of errorsaffects experimental outcomes. Table 1 presents the averagesof all student data obtained for this investigation.

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862 Journal of Chemical Education • Vol. 75 No. 7 July 1998 • JChemEd.chem.wisc.edu

Physical PropertiesThe question posed to the students for this investiga-

tion was: What types of intermolecular forces (excluding hy-drogen bonding) are most important in determining theproperties of a series of liquids? Students could measurevapor pressure as a function of temperature, dipole moments,density and viscosity. They were given a supply of acetone,2-butanone, and 2-pentanone. Hexane, necessary for themeasurement of dipole moments (25), was also available asa nonpolar solvent.

This lab is designed to challenge students’ notion thation–ion forces are the “strongest” intermolecular forces andthat induced-dipole–induced-dipole forces are the “weakest”.Since each type of intermolecular force has a unique dependenceon distance, induced-dipole–induced-dipole (dispersion)forces usually have a much greater collective effect on thephysical properties of a liquid than the “stronger” dipole–dipole forces. In addition, this lab requires students to presentcorrelations between two measurable variables. Table 2 presentsthe averages of all student data obtained for this investigation.

Isomerization of Push-Pull AzobenzenesThe question posed in this investigation is: What is the

more likely mechanism for the isomerization of push-pullazobenzenes: inversion or rotation? Students have a flash pho-tolysis unit available with a variable temperature cell and cir-culating water bath. Also available are a range of solvents andthree azobenzene derivatives. The derivatives are chosen toprovide a variety of donor groups.

This investigation is designed so that students think criti-cally about the process of proposing a mechanism for areaction. Push-pull azobenzenes undergo a cis-trans isomer-ization, which can be studied using flash photolysis. The cisisomer is prepared photochemically and the relaxation backto the trans isomer is observed. The mechanism for thisisomerization has been argued in the literature (26–29). Bothan inversion mechaism and a rotation mechanism have beenproposed. Students were told that they must support one ofthese mechanisms based on their data. The change in rateconstant when the solvent and donor substituent are changedpoint to a dipolar transition state such as is necessary for arotation mechanism (26–29). However, the tempera-ture dependence results in a slightly negative entropyof activation, which is consistent with an inversionmechanism (26, 27). These contradictory pieces ofinformation present students with a dilemma theymust resolve in order to present the project in finalform. Tables 3 and 4 present the averages of all stu-dent data for this investigation.

Conclusions

The initiative described here employs many ofthe learning techniques that have been found to besuccessful for first- and second-year college scienceteaching. Students are required to construct theirknowledge of an investigation by forming an experi-mental plan (21, 22). They are required to collabo-rate on relatively open-ended 3-week projects (1–13,23, 24). They are actively engaged by peer-teachinglearning strategies (23, 24) and they are guided by

the instructor throughout the investigation (1–13).This reform of the physical chemistry laboratory course

was undertaken to build on the successful programs imple-mented in the first four semesters of the chemistry curriculumat many institutions. In addition, there was a real frustrationwith ill-prepared students and student apathy in the physicalchemistry lab. Our reform has answered these challenges inmany ways. Students cannot come to lab ill prepared. With-out a plan they are not allowed to perform any experiments.Because students must construct their own experimental pro-tocol, they are actively engaged with the investigation fromthe very beginning.

Students are more likely to actively participate in the in-vestigation if questions are designed to pique their interest.In the examples given, students are asked to answer two typesof questions. Some questions are designed so that studentsare not likely to know the answer (calorimetry and cis-transisomerization kinetics). Other questions confront commonmisconceptions (physical properties). Students may think theyknow the answer before beginning, but are soon forced toface a misconception and reconcile their data with theirflawed intuition.

Finally, students often have unrealistic expectations about

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how science is done. The long-held belief that science is asolitary pursuit done by people in white lab coats who seldomstop to eat or sleep—let alone talk to another human being—is unfortunately alive and well. Our approach to a physicalchemistry laboratory course confronts this misconceptionhead on. More than half of the activities are performed as agroup. Students quickly realize that developing skills to workwithin a group and collaborate on a project is at least as im-portant as obtaining good results and understanding thechemistry involved in the project. This should prove to bethe single most valuable lesson that students learn from thisapproach to physical chemistry laboratory.

Acknowledgment

This work has been supported by the National ScienceFoundation through grant number DUE-9455928, Establish-ing New Traditions: Revitalizing the Curriculum, awarded tothe University of Wisconsin, Madison, WI.

Literature Cited

1. Ricci, R. W.; Ditzler, M.A. J. Chem. Educ. 1991, 68, 228–231.2. Varco-Shea, T. C.; Darlington, J.; Turnbull, M. J. Chem. Educ.

1996, 70, 536–538.3. Kildahl, N; Berka, L. H. J. Chem. Educ. 1995, 72, 258–260.4. Deavor, J. P. J. Chem. Educ. 1994, 71, 980–982.5. Lloyd, B. W.; Spencer, J. N. J. Chem. Educ. 1994, 71, 206–209.6. Cooper, M. M. J. Chem. Educ. 1994, 71, 307–309.

7. Lamba, R. S. J. Chem. Educ. 1994, 71, 1073–1074.8. Coppola, B. P.; Lawton, R. G. J. Chem. Educ. 1995, 72, 1120–1122.9. Juhl, L. J. Chem. Educ. 1996, 73, 72–77.

10. Anderson, J. S.; Hayes, D. M.; Werner, T. C. J. Chem. Educ. 1995,72, 653–655.

11. Jasien, P. G. J. Chem. Educ. 1995, 72, 48.12. Holme, T. A. J. Chem. Educ. 1994, 71, 919–921.13. Costa, V. J. Coll. Sci. Teach. 1993, 23, 49–53.14. Walters, J. P. Anal. Chem. 1991, 63, 977A–985A.15. Walters, J. P. Anal. Chem. 1991, 63, 1077A–1087A.16. Walters, J. P. Anal. Chem. 1991, 63, 1179A–1191A.17. Ross, J. R.; Fulton, R. B. J. Chem. Educ. 1994, 71, 141–143.18. BelBruno, J. J. J. Chem. Educ. 1994, 71, 309–311.19. Shields, G. C. J. Chem. Educ. 1994, 71, 951–953.20. Moore, R. J.; Schwenz, R. W. J. Chem. Educ. 1992, 69, 1001–1002.21. Miller, T. L. J. Chem. Educ. 1993, 70, 187–189.22. Bodner, C. M. J. Chem. Educ. 1986, 63, 873–878.23. Johnson, D. W.; Johnson, R. T.; Smith. K. A. Active Learning:

Cooperation in the College Classroom; Interaction: Edina, MN, 1991.24. Johnson, D. W.; Johnson, R. T.; Smith. K. A. Cooperation and

Competition: Theory and Research; Interaction: Edina, MN, 1989.25. Wilson, J. M.; Newcombe, R. J.; Denaro, A.R.; Rickett, R. M.

W. Experiments in Physical Chemistry; Pergamon: New York, 1968;pp 135–137.

26. Marcandalli, B.; Pellicciari-Di Liddo, L.; Di Fede, C.; Bellobono,I. R. J. Chem. Soc. Perkin Trans. II 1984, 589.

27. Wildes, P. D.; Pacifici, J. G.; Irick, G., Jr.; Whitten, D. G. J. Am.Chem. Soc. 1971, 93, 2004.

28. Kobayashi, K.; Yokoyama, H.; Kamei, H. Chem. Phys. Lett. 1987,138, 333.

29. Asano, T.; Yano, T.; Okada, T. J. Am. Chem. Soc. 1982, 104, 4900.