A Computer-Interfaced Physical Chemistry Laboratory: Some Personal Experiences.

A start-up grant from the Chemical Education Trust Fund enabled student to have a more enjoyable experience in introductory physical chemistry.

The chemistry faculty at Sir Wilfred Grenfell College has always tried to be innovative; [1-3] for example, we recently introduced a chemistry

1. A unique minilab format for our preparatory chemistry course that enables students to relate chemical theory to experimentation (l985); [5]

2. Microscale techniques for the general chemistry course that result in more efficient use of laboratory time and a significant reduction in chemical waste (1994); [6]

3. Semi-micro flameless techniques for the organic chemistry courses that permit synthesis of organic compounds by classical techniques to be accomplished more quickly, more safely, and with minimal waste (l986); [7]

4. A novel descriptive inorganic chemistry laboratory program that integrates the theoretical and practical aspects of the subject (1999).

More recently, our attention turned to the only other pure chemistry course in our repertoire: the one-semester of introductory physical chemistry common to both campuses of Memorial University. The content, part chemical thermodynamics and part advanced concepts of solution equilibria, is designed for students in the SWGC environmental science (chemistry) program, the MUN chemistry program, and for the MUN biochemistry and pharmacy programs. The experiments relating to solution equilibria start by being pH-based, then rapidly progress into electrochemical, mainly conductivity, studies. Each of these experiments has involved considerable quantities of manual data collection and graph plotting; for example, to interpret the introductory titration curve, students have to plot not only pH against volume added but also the first and second derivative curves. The thermodynamic experiments, requiring similarly large amounts of data collection and graphical plots, involve the measurement of temperature or potential to determine values of thermodynamic functions and to study phase change phenomena.

Our students found the hours of graph-plotting to be laborious and time-consuming when they had so many other study-time commitments. In addition, if a mistake had been made in the performance of the experiment, the error was not spotted until too late. During the Fall of 1998, we had the students utilize a spreadsheet to plot the data, but this change still required the students to enter all the numbers into the computer and then spend time trying to manipulate the columns of values to produce useful plots.

We decided the answer was to computer interface the experiments for the entire laboratory course. Until recently, one had to choose between interfaces of limited usefulness with simplistic DOS-based software, or sophisticated but very costly systems. It is now possible to purchase low-cost high-performance interfaces equipped with a wide range of probes and accompanied by sophisticated software capable of curve fitting and differential plotting, among many other tasks. Thus we thought that computer-interface technology might offer the following advantages:

1. Enable the students to process the data simultaneously with the data acquisition, making the numerical values immediately meaningful;

2. Introduce the students to the current technology;

3. Provide the opportunity to introduce new, innovative, and more relevant experiments in the course;

4. Permit the students to acquire valuable computer-related skills, thus enhancing future employment prospects;

5. Save time in processing of results by students who currently have extremely heavy workloads in their second year;

6. Allow the students to manipulate data more meaningfully by routinely using differential plots and curve fitting where applicable.

After studying the various packages on the market, we decided that the Vernier(R) interface system offered the best value for money. An added consideration was that our specific questions were always replied to promptly by the company-an important consideration for our circumstance. The interfaces could be linked to pH, conductivity, temperature, voltage, and specific ion electrodes. The Windows-based Logger Pro software was user-friendly and there was a supplementary program, Graphical Analysis, that could be used for more advanced manipulation of data. Unfortunately, we were unable to persuade the College administration of the importance of our proposal and of the need to fund it. To our joy, we were able to obtain a starter grant from the Chemical Education Trust Fund. This enabled us to purchase the interfaces. Having gained credibility by means of the starter grant, we were able to acquire contributions from Foundation sources to furnish the computers and related items.

Unexpectedly, the major problem was not with the choice of computer system or interface, but with logistics. The main Crenfell College laboratory is multi-purpose, thus the computer and interface systems could not be permanently bench mounted. As a result, we needed to find a mobile cart that would enable us to wheel the computer-interface combinations in and out when needed. The cart had to be very stable (to cope with the top-heavy monitor), with sturdy wheels (to take the weight), yet occupy the minimum lab space (so that we could fit 12 carts in the lab without blocking isle access). After some trial and error, we found the Flexi-Height Workstations, supplied by Misco, to be just what we needed. These carts could be adjusted to exactly bench height, they are extremely stable, and are quite compact.

To ensure that we discovered any problems before leaping into a 100% computer-interface based course, over the summer of 1999, we selected about 20% of the experiments to modify initially. At the beginning of the semester, one of us (Strickland) gave a workshop to students (with an accompanying handout) in one of our computer labs on how to use the Logger Pro program. This workshop was vital, as we required the students to do derivative curves for the pH and conductimetric titrations and to expand and curve fit the portion of the plot about the equivalence point. Though some students were highly computer literate, there was also a large minority who had no computer experience other than very elementary word-processing.

As the Fall of 1999 progressed, it became apparent that the adoption of interfaces was a great advance. The students enjoyed the experiments much more when they could actually see the plots of their data appearing on screen. They soon became adept at selecting derivatives, expanding-portions of plots, and obtaining slopes. Several of the students had been warned by their predecessors of the long evening grind of data plotting associated with the course, thus they were delighted to become the first "guinea-pig" class free of such drudgery. There were absolutely no negative features of the change.

So to the future: the summer of 2000 will be spent devising and testing other experiments that utilize the full potential of the interfaces. We plan to purchase keyboard skins to minimize the effect of solution spillage on the keyboards, and we are hopeful that a uv-vis spectrophotometer can be linked into the interface as well, enabling us to expand our repertoire of experiments further. Having had such a positive experience with the second-year p-chem course, we are now looking into the usage of these versatile and adaptable interfaces for first year kinetics and elementary titration experiments, in addition to applications in our third and fourth year environmental chemistry courses. However, we will be careful not to be dazzled by excessive dependence on new technology and continue to retain a healthy balance of qualitative and quantitative experiments in our first-year lab program.

In conclusion, then, we strongly recommend computer-interfacing for use in introductory physical chemistry laboratories.

Acknowledgements

We are most grateful for the starter grant from the Chemical Education Trust Fund, without which this project could never have occurred. We also thank the George Cedric Metcalf Charitable Foundation, the S.M. Blair Family Foundation, and the Birks Family Foundation for subsequent financial support.

Geoff Rayner-Canham, FCIC; Wanda Ellsworth; Dean Strickland, MCIC; and Debbie Wheeler are with the chemistry group of the environmental science unit at Sir Wilfred Grenfell College, Corner Brook, NF.

References

(1.) Alper, A., 'The Chemistry Department at Sir Wilfred Grenfell College', Chem. Canada, 35(10): 9-11, 1983.

(2.) Abhyankar, S.B., A.M. Last, P.K. Monaghan, R.R. Perkins, G.W. Rayner-Canham, J.N. Reed, and M.J. Webb, 'Scholarship and Chemistry Teaching in the Two-Year College', J. Chem. Educ., 68:145-148, 1991.

(3.) Michael, T.H.G., B.T. Newbold, L.W. Shemilt, and A.W. Tickner, Chemical Canada 1970-1995, The Chemical Institute of Canada, 1995, pp. 160-161.

(4.) Abhyankar, S.B., J.M. Dust, D-R. Parkinson, and G.W. Rayner-Canham, 'Environmental Chemistry at Sir Wilfred Grenfell College', ACCN, 50(3):16-17, 1998.

(5.) Webb, M.J., G.W. Rayner-Canham, and A.M. Last, "The Minilab: A Novel Approach to Freshman Chemistry Experiments', J. College Sci. Teaching, 15(5):448-453, 1986.

(6.) Rayner-Canham, G.W., 'Microscale Methods in General Chemistry', Educ. Chem., 31:68-70, 1994.

(7.) Abhyankar, S.B., and N.J. Reed, 'Undergraduate Semi-micro Organic Labs: Taking the Middle Path', ACCN, 39(8):19-21, 1987.