edited bv
computer series, 153 Using an Electronic Spreadsheet in the Design of Exercises for a Polymer Laboratory Course W. W. McGee and Guy Manson University of Central Florida Orlando. FL 3281 6 The Chemistrv .Department a t UCF recentlyreceived an NSF grant to develop a laboratory course in p&mer chemistry (1).In this course, students synthesize polymeric materials and then evaluate the properties of these materials usine modern instrumental techniques. The goal of each laboratory exercise is to illustrate the relationship between the svnthesis procedure and the -properties of the resultant poiymeri~materials. Instruments purchased for the materials testing portion of the laborntory are the type commonly found in the modern industrial polvmer testing laboratory Where possihle, instruments use-an external PC to record and process data. We intend for students to make extensive use of the PC to complete each laboratory exercise. Development of a laboratory manual for this course proved to be challenging. For the synthesis portion, laboratory directions were prepared in the form of a typed class handout. For the materials testing portion, directions were prepared on paper and disk for class distribution. Early attempts using typed directions for instrument operation and directions on disk for data collection and processing proved unsatisfactory. This manner of presentation seemed unwieldy and lacked continuity. Clearly what was needed was an electronic organizational device that would facilitate assembling all components of the experiment on disk. This device should contain provisions for composing textual information, collecting data from instruments, manipulating data using mathematical relationships, graphing data, and performing statistical calculations. The electronic organizational device t u r n e d o u t to be t h e integrated spreadsheet (word processorlspreadsheet combination). I n this article, we discuss the use of the integrated spreadsheet in the development of laboratory experiments for the polymer chemistry laboratory. We plan to present specific details of each laboratory experiment a t a later date in this Journal. &
Integrated Spreadsheet The integrated spreadsheet contains many features that can be used in the construction of scientific laboratory experiments:
S~readsheetFormat. The column and row format of the spreadsheet is particularly appealing to the psyche of the scientist. Data can be organized in a logical fashion. Spreadsheet cells provide a means of manipulating data and making mathematical calculations. The spreadsheet can he used to create files containing data imported from instrument sources. .Graphics Capabilities. Graphing data provides a means of visualizine mathematical relationshi~sand far testins re-
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Journal of Chemical Education
JAMES P. BIRK Arizona State University Tempe, AZ 85281
dent. It provides a way for students to communicate the results of an experiment. 'Extended Capabilities. Many instrument manufacturers provide data exchange routines that permit data to be generated in a format that can be imported directly into a spreadsheet file. .Macro Capabilities. Macro commands a r e a type o f spreadsheet language that pmvide a means of "automating" spreadsheet operations. Macro commands provide the means of moving throueh the com~onentDarts of an electrunir lnhrntoene (PSI is synthesized using both suspension and emulsion free radical procedures. The number and weight average molecular weight of the product from each reaction as measured bv gel penneation chromatography (GPC) should be significantly different. The Backmound section for this experiment contains a discussion of polymer molecular wight, the theory and operation of the GPC, and a brief review of ASTM procedures D 3536 and D 3593 (7,8). The purpose of the SafetylSafe Disposal section is to familiarize students with the hazards and risks involved in conductine each experiment. For the PS exoeriment.. this section contains a kiscussion of the hazardous nature of each chemical involved. a list of oertinent safetv Drecautions, and directions fo= safe disposal of waste materials generated. The Experimental Procedures section is the most involved and complex of the five sertions. I t is in this section that the power of the integrated spreadsheet to organize a wide variety of complex laboratory operations is apparent. In the PS experiment, students measure the effect of synthesis conditions on molecular weight as measured by GPC. The molecular weight profile of each PS sample is recorded using a previously calibrated GPC. The molecular weight values are calculated from each profile wing commercial chromatography software (PE-Nelson). The Experimental Procedures section for the PS contains:
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Contains General lnformation Pertinent to Each Experiment Submenu Three: Experimental Procedures. 1. Detailed Procedures Submenu Four: Data Analysis, Questions, and Final Report.
Y
Submenu Five: Safety Precautions and Safe Disposal Practices.
Diagram of the structure of a typical electronic laboratory experiment.
A text fde describing the preparation of PS standards for calibrating the GPC and the preparation of PS samplesfor GPC
analysis. 123/Wordoerfect).the student calls the exoeriment bv twing M A I ~ E At ~ that . moment the experiment i s &tive. and the main 'Table of Contents" for the emeriment is displayed. All parts of the experiment can be called from this menu. Makine a selection from the menu is the electronic equivalent of turning the pages in a traditional laboratory textbwk. Instructions for selecting a n item from a menu are found a t the bottom of each menu. Should the student become lost in the electronic maze, the main "Table of Contents" can be accessed with a series of s i m ~ l e keystrokes. Design of Component Parts of an Electronic Laboratory Experiment
As shown in the fieure, each laborator, emeriment is organized into five iecti'ons. Each sectibn has its own "table of contents" (submenu) that orovides electmnic access to the component parts of that section. While the specific contents of each section depend on the experiment, electronically the construction of many sections is similar. Typically, a section will contain text fdes, spreadsheet files, and macro tools that can be selected from its submenu. For example, the Overview, Background, and Safety sections consist of text files linked bv macros to the aoorooriate submenu. The Overview section consists of three or four component parts titled: New Concepts, Prelab Preparation, Laboratory Measurements, and Selected References. The goal of this section is to focus the students' attention on new and important aspects. Each component part is written a s briefly and succinctly as possible without sacrificing comprehension. For example, the Lab Measurements component is a list of data to be collected. We encourage students to print this section before class so that it can be used as a checklist to follow. A.
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A text file listing the operating conditions for the GPC. . A text file describing the operating conditions for the PE-
Nelson interface and chromatography software. .A macro tool for converting a PE-Nelson data file into a
Lotus compatible .PRN file. .A macro tool for importing the data file into the Lotus
spreadsheet. A macm tad to assist the student in viewing the GPC chromatogram of each PS data file.
All of these complex activities are macm driven and arcessible from the Experimental Procedures submenu. The Data Analysis section is the communication section. In this section, the student organizes the data collected, performs mathematical and statistical calculatious, graphs the results and reports the results of the experiment. In the PS experiment, students are asked to calculate manually the number and weieht-average molecular weights fbr one of the PE samplesy~hestudent is asked to compare the manually calculated molecular weiehts with those calculated by the chromatography soitwa& (in seconds!) and discuss the results. From this exercise, we hope students will gain a better understanding of the mechanics of making the calculations and insight into potential sources of error. The Data Analysis section for the PS experiment contains the following: 'A text file describing the manual calculation uf number and wrighr average mulerular weight from a CPC chromato-
gram. * A spreadsheet file containing a template for making a the calculation of number and weight average molecular weight. Students must provide cell formulas to calculate the molecular weight averages. .Spreadsheet files containing the raw data for PS samples analyzed. Volume 70 Number 9 September 1993
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