The Internet Chemistry
Set: Web-based Remote Laboratories for Distance Education in Chemistry
Frederick A. Senese, Frostburg State University
Christopher Bender, Frostburg State University
Jennifer Kile, Frostburg State University
The convergence of modern data acquisition technologies with the Web's interactivity, connectivity and multimedia capabilities presents an exceptional opportunity for distance education in the physical sciences. Web-mediated access and control of laboratory equipment can improve utilization of expensive and specialized instruments, facilitate collaborative data sharing and analysis, and provide essential practical experience in physical science courses delivered at a distance.
This paper describes a remotely controlled experiment for determining the rates of fast chemical reactions. The experiment is not a simulation; it involves actual equipment controlled in real time from remote locations on the Web. The experiment is the first in a series designed to provide a pedagogically sound on-line laboratory experience for Web-delivered general chemistry courses. Students use the experiment's Web interface to collect data, to obtain interactive technical support and background information, and to display and analyze results. Each experiment is designed to encourage sharing of data and collaboration with users at other institutions, providing students with a valuable first look at work in a distributed laboratory environment.
Chemistry is an experimental subject. Chemists construct knowledge by systematically examining quantitative data for patterns. Patterns suggest hypotheses, which in turn form the basis for theories. Theories are then critically evaluated in the light of new experimental data. This is the only sanctioned approach for progress in science. Pedagogy that is not founded on the interplay between theory and experiment poorly serves students by not involving them in the essential process of science.
The experimental nature of chemistry presents severe challenges for teaching the subject at a distance. Many current online chemistry courses either have no laboratory experience at all or use simple kits or 'kitchen chemistry' experiments that can be performed with household materials. Obtaining accurate, quantitative data from which relevant and interesting conclusions can be drawn is difficult with such simple equipment.
Online chemistry courses often make heavy use of simulations. While simulations can be quite effective, they are theoretical constructs that cannot substitute for practical experience. For example, students regarded the output of simulations in a statistical analysis experiment at Oxford University as "pretend" data (Cartwright, 1998). They sometimes failed to carry over the lessons learned from analyzing simulated data to data collected in actual experiments. Concerns about the pedagogical quality of the simulations were addressed by the development of a simple, economical "optical rig" (Cartwright, 1999), which allows students to collect and analyze actual data over the Internet.
This project addresses the problem of practical experience in Web-delivered courses by providing students with remote access and control of real equipment. A remote-control reaction kinetics experiment suitable for chemistry students at the undergraduate or advanced secondary level is described. The apparatus monitors the course of a fast chemical reaction spectrophotometrically using a simple continuous flow method. Students can use the data they collect to determine the rate laws for the reaction under a variety of conditions. By collaboratively analyzing the results of a large group of experiments performed by peers, students can propose mechanisms for the reaction. While the experiment is conceptually quite simple, it involves specialized apparatus that is unavailable in most undergraduate laboratories. Rapid data acquisition can allow many users to perform experiments in real time, and nearly spontaneously.
The experiment is an adaptation of a classic continuous flow method for studying the rates of fast reactions (Dalziel, 1953; Roughton & Chance, 1963). The apparatus can be used to determine the rate of any sufficiently fast reaction that produces a colored product, although practical considerations limit the choice of reaction (Shoemaker, 1974). Pilot investigations studied the formation of FeSCN2+ (an orange complex that absorbs at blue light at 455 nm) and the metallochromic indicator Eriochrome Black T.
A schematic diagram of the apparatus is shown in (Fig. 1).
Figure 1. Schematic diagram of the apparatus
Reactant solutions are forced from large reservoirs into a T-shaped chamber, where they mix completely in less than 1 millisecond. The reacting mixture then travels down a long capillary tube. The product of the reaction is intensely colored and strongly absorbs a characteristic wavelength of light. Product concentration rises as the mixture moves along the tube. Seven light sensors placed at fixed positions along the tube monitor the increase in concentration. Monochromatic light is passed through the capillary at each position using a fiber-optic cable. High sensitivity photocells placed on the opposite side of the tube record the intensity of transmitted light at each point; the intensity drop caused by absorption of the light by the complex is simply related to the concentration. A flow rate sensor allows the position of each of the spectrophotometers to be associated with a reaction time.
Data from the sensors is acquired by "sanzone," a 500-MHz PC equipped with a National Instruments data acquisition card. A LabView program collects, labels, and writes the absorbance, temperature, and flow rate data to an "outgoing" queue. The program then checks for requests in an "incoming" queue. If one exists, a new run is started. Otherwise, the system is flushed and the valves are closed to avoid unnecessary waste of reagent solutions.
The Labview program includes a very simple graphical interface that can be used to control the apparatus onsite; this interface will be used in the assessment phase of the project to compare the performance of students accessing the experiment online and offline.
Figure 2. Labview monitor
A Webcam collects pictures of the apparatus during the run. The camera view includes the reservoir manometer and a digital thermometer, so it is used for data collection as well as for helping students monitor the progress of the reaction. The Webcam is attached to a second PC to avoid contention.
A Unix Web server (Marie) mounts Sanzone's hard drive across the local network. Perl scripts running on Marie fetch data from the outgoing queue, interpret it, and prepare the results for display.
Students perform the experiments
via a "smart" instrument panel served from Marie, displayed in a standard
browser. The instrument panel recreates the actual look and feel of the remote
experiment. Operators immediately see the results of their actions via the Webcam,
as well as on a rich data display. The panel's panic button launches a conferencing
connection with the system's caretaker via Netmeeting during working hours and
by email at other times. The panel monitors and interprets student activity
to diagnose and correct conceptual problems and to prevent actions that could
damage or tie up the apparatus for long periods of time.
Demo 1 Kinetic GUI Flash demo
The instrument panel front end is implemented in Macromedia Flash. When students submit a run from the instrument panel, backend Perl scripts label and process the request and write it to an "incoming" queue on Sanzone, and the expected time of completion for the job is displayed on the panel. Jobs can be completed in seconds when the incoming queue is empty. Queues are intelligently managed by consecutively scheduling jobs with similar operating parameters and by assigning lower priority to non-local IP addresses (to prevent 'walk-in' users from monopolizing the experiment).
Future versions of the experiment will allow students to manipulate additional parameters, such as reagent concentrations, pH, temperature, ionic strength, and flow rate. Data from different groups can then be pooled and analyzed. Students will then use these results to evaluate proposed mechanisms for the reaction. Further developments will be outlined on the project home page at http://antoine.frostburg.edu/chem/senese/inetchemset.
External links to : Internet chemistry set project
We plan to assess the experiment and its interface by comparing the performance of four test groups. The assessment will use a test designed to probe a student's ability to connect experimental data with kinetic concepts and reaction mechanisms. The control group will perform the experiment onsite, using the Labview monitoring panel directly for data collection. Group two will perform the experiment using only the Labview panel online. Group three will use the Flash interface online. Group four will use the Flash interface to perform the experiment, and collaborate with other groups on the experiment's bulletin board to compute activation energies and propose reaction mechanisms. Each group will be asked to critically summarize their experiences. The results of this study will be reported in a future article.
Cartwright, H. M. (1998). Remote control: How science students can learn using Internet-based experiments, in New Network-based Media in Education; Proceedings of the International CoLoS Conference, Maribor, Slovenia, 51?59.
Cartwright, H. M. (1999). An Internet-based Experiment in Error Handling. International Conference on Conceptual Learning of Science, Lisbon, Portugal.
Dalziel, K. (1953). Journal of Biochemistry, 55, 79-94.
Gillet D., Ch. Salzmann, R. Longchamp, D. Bonvin, "Telepresence: An Opportunity to Develop Practical Experimentation in Automatic Control Education", European Control Conference, Brussels, Belgium, 1997.
Roughton, F. J., & B. Chance (1963). Rapid Reactions, in Techniques of Organic Chemistry, 2nd ed, S. L. Friess, E. S. Lewis, A. Weissberger (eds), v. VIII, Interscience-Wiley, New York. 704?778.
Salzmann Ch., D. Gillet, R. Longchamp, and D. Bonvin, "Framework for Fast Real-Time Applications in Automatic Control Education," 4th IFAC Symposium on Advances in Control Education, Istanbul, Turkey, 1997.
Salzmann Ch., H. A. Latchman, D. Gillet, and O. D. Crisalle, "Requirements for Real-Time Experimentation over the Internet," International Conference on Engineering Education, ICEE '98, Rio de Janeiro, Brazil, 1998.
Shoemaker, D. P.; Garland, C. W.; & Steinfeld, J. I. (1974). Experiments in Physical Chemistry, New York: McGraw-Hill. 335.
********** End of Document
|IMEJ multimedia team member assigned to this paper||Ching-Wan Yip|