antiparallel relationship between the equatorial suhstituents and the vicinal ring carbons, and emphasizes the parallel relationship of the lines used in drawing a cyclohexane chair conformer. Practice in placing the e ~ u a t o r i asuhstituents l is provided by permitting the student t o move a bond and attached suhstituent about the Screen in order to place it in the appropriate position (see Fig. 3). The six equatorial suhstituents can he placed in this manner. 'l'he third >errion cuniirts of s,wr of prot)lems in which the a nmrurmarwn d n sl~eriiic itudt.nt I; asked ~ o d r a u particular dimethylcyclohexane (for example, the most stable conformation of cis-1,2-dimethylcyclohexane).The student can d a c e the substituents on the rine. ,.. which has all axial and equatorial bonds already attached, by entering the position number and the desired equatorial or axial orientation. A methyl group is then placed in the requested position by the .Droeram (see Fie. 4). Carbon-1 is randomlv selected creatine a variety of correct answers to a problem; an individual problem may be repeated by a student a t any time so that the variety of ways of drawing a particular substituted cyclohexane can he seen. Responses to incorrect answers are tailored to the type of error. Help and scoring are provided if requested, and exit to the menu is available a t all times. The program can he easily modified to include additional examples, or to change screen commknts, or to change timing delays in order to illustrate the effect of temperature on the inversion process. Program CYHX-1. Written in IBM-PC BASICA, 260 statements, 62 remarks, 16 K-byte file size. Requires 64K of 8-hit words and single disk drive. Available from SERAPHIM. ~
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THERMPRD-A Thermodynamics Program1 Bhairav D. Joshi State University College at Geneseo Geneseo. NY 14454 THERMPRO is an interactive screen-oriented computer program written in BASICA for an IBM-PC with a graphics ca~abilitv.It reoresents a eeneral method of calculatine standard thermodynamic pibperties of chemical reactions from heat caoacitv data for reactants and oroducts. The program a t prksenirequires about 35K bytes &RAM. It uses a menu approach and provides the options summarized below.
temperatures are involved. The table is saved for subsequent graphing requests. 8) Plot, using high resolution graphics, the standard thermodynamic properties against temperature-one plot per frame. The axes are scaled to provide the maximum resolution possible. Scales, scale-factors, and the axes labels are clearly shown on the graph. For Whom is It Intended?
1) Four-year college and university students studying thermodynamics. 2) College and university professors who are teaching thermodynamics.. 3) People involved in writing exam and review questions on the subject of reaction thermodynamics; texthook authors. Unique Features
1) Intended for use by one to three persons a t a time. 2) A friendly and interactive style makes the program easy to use. 3) Uses color, sound, and blinking to keep the attention and interest of the user on the suhject. 4) Any reaction among the chemicals in the THERMAL.DATa file can he studied. Thus the potential scope of this program is virtually unlimited. 5 ) Since THERMPRO provides facilities for modification of data file, users can readily adapt it to their specific needs. 6) It uses general expressions for calculating standard thermodynamic properties of reactions. These formulas are derived using the following most flexible expression for CPo of compounds representing the available data in the literature. C," = A I
+ A2T + AsT"
A4T'
+ BIT'
The values of the coefficients At, A2, A3, Ad, and B for various compounds are given in physical chemistry literature. Thus, THERMPRO represents ageneral method as well as a specific program available for IBM-PC. Hardware
IBM-PC with 64KB of RAM; Dual Disk Drives; Color1 Graphics Monitor, and Adaptor Card; DOS 1.1 or 1.0 Software
1) Create and initialize a random-access data file, THERMALDATa, for storing experimental data from the literature for up to 100 different chemical compounds. 2) Add data to the THERMAL.DATa file, which currently contains data for 26 compounds frequently encountered in thermodynamics courses. 3) Update the d i t a in THERMAL.DATa file. 4) List the THERMAL.DATa file on the screen, one record a t a time. 5) Collect information ahout a reaction of interest via the keyboard using a simple conversational mode. 6) Calculate the following standard thermodynamic properties of a reaction a t any temperature T for which the THERMAL.DATa is valid:
One Diskette (single sided, double density) containing THERMPRO and THERMAL.DATa file is available from the author for $25.
ACD0,AHo, AS', AGO. AEo, AA", and K
We have orenared . . and used a series of comuuter .nroerams . for the quantitative analysis laimratory course. These calculate, from student data, the results of each experiment. Ten different experiments are carried out in the one semester course; they are listed in Table 2. These include classical gravimetric and titrimetric determinations, as well as applications of the classical methods to commercial products. The input for the computer programs are in the form of sample weight, volume of titrant, etc. Output from these programs is in the form of percent desired component, con-
7) Calculate and tabulate (on the screen) all of the above properties of a reaction for up to 100 different values of temperatures from T, to T 2in steps of dT. The screen display is organized into various pages for cases where more than 12
' Paper presented at the 16th Annual Small College Computing Symposium. St. Olaf College. Northfield, MN. March 25-26. 1983.
Computer Calculations in Spanish for the QuantitativeAnalysis Course Rafael Inlante-Mbndez Catholic University of Puerto Rico Ponce. PR 00732
Volume 60
Number 9
S e ~ t e m b e r1983
733
Table 2. OuantltaNve Analysis Frograms In Spanlsh Laboratory Experiments 1)
Determination of the Water Content of a Sample iron
2) Gravimetric Determination of 3) Determination of Soda Ash
Determination of the Equivalent Weight of an Organic Acid 5 ) Photometric Titration of Cu(ll) with EDTA 61 Determination of lron in Mineral Ores by Potentlametric Titration with Potassium Dichromate 7) Photometric Determination of Manganese in Steel 81 Photometric Determination of iron 9) Potentiometric Determination of Chloride in Commercial Products Using a Chloride ion-Selective Electrode 10) Evsiustion af Commercial Antacids 4)
Program WATER FEGRAV
SODASH PH
CUSPEC FEREOOX
MNSPEC FESPEC CL ANTI
centration of desired component, etc. The programs, in addition, tabulate mean values and relative average deviation (parts per thousand). Six of the programs have plotting routines. These allow for potentiometric titration curves and derivative curves, spectrophotometric titration curves, the absorption spectra for manganese and iron, and the calibration curves for the iron and chloride analysis to be shown graphically on the monitor. The programs have the option of making a hard copy of the graphs if the student desires ao. Two of the programs, the spectrophotometric titration and the chloride analysis, allow for a least squares fit of the data. These programs have proven useful in instructing beginning students in quantitative analysis. They also give students practice in working with computers, many thought that the computer was a good way to learn. The oroerams are written in BASIC for a TRS-80 Micro. " computer. All instructions to a student user are in Spanish. Available from SERAPHIM.
Computerized Quizzeswith Instant Grading and Response Analysis Donald A. Bath and Ben G. Hughes Western Illinois University Macomb. IL 61455 Since purchasing a mark-sense-card reader for addition to our TRS-80, Model I microcomputer system, the Department of Chemistry a t Western lllinois University has found many ways to use this device. Whenever data can be easily presented on marked cards and rapid turnaround is needed, the card reader has proved to be a most useful peripheral on our system. A specific application of the card reader is the administration and evaluation of pop quizzes for small classes of students (about twenty each). The software for this application, called INSTQUIZ, consists of a master program that accepts the data input through the card reader, locates the student in a file of names and grades, calls the correct answers for the quiz from a file of answers, evaluates the students' responses, and records the results in the students' grade file. Supporting programs are required to set up the student record files, to set up the answer files for the various quizzes, and to read and evaluate each of the grade files after the quizzes have been given. INSTQUIZ allows answers for ten different quizzes to he stored, with the ootion of wine one or as manv as all ten simultan~ously.hec cards have space for ten answers which mav be either multiole choice or numerical. Provision is made for'accepting answers within a rangeestahlished by the instructor for each individual question. Awarding of partial credit is also possible. Obtaining results of the quizzes given to various classes is accomplished through two additional programs. The first of these reads out the student files, totals the scores for each 734
Journal of Chemical Education
student and allows assignment of grades. The second presents an analvsis of the answer files showine the numher of students that goi each answer right, the numbkr that got it wrong, and the percentage gi\,ing t he (.i~rrectanswer. JSS'I'QI'JZ cont,#ln>?It; Iinw (gf HASl(' in one maswr program and four supporting programs. It was designed for the Radio Shack TRS-80 Model I with one disk drive. NEWDOS-80, Version 2, is the operating system hut files are set up and read in the random file format compatible with TRSDOS. The card reader is an MR-500 from Chatsworth Data Corporation. Copies of the listing and documentation are available for a self-addressed stamped envelope sent to the authors a t the above address.
Computer Simulation of Elementary Chemical Kinetics Martha L. Nase and Kurt Seldman Randolph-Macon Woman's College Lynchburg, VA 24503 The authurs have developed several computer programs that simulate chemical kinetics for elementary first- and second-order processes. These programs can he used to generate kinetic data that can then he analvzed hv the student in a variety of ways. We have found these programs to be a much more beneficial learnine exoerience for the students than other programs which, more &pically, analyze the data for the students. In addition. the nroerams can he used toillustrate several kinetic principles.hecause of the unique way in which they generate the data. Each of the above-mentioned programs treat one of the following general elementary reactions: A
A
+A
A
+B
-
products
(1)
products
(2)
products
(3)
A description of the program that treats first order kinetics, reaction (11, follows. The same general approach was used with the second-order programs with some slight modifications that will be briefly described later. The oroerams were written for a Radio Shack TRS-80 . ,. h l d e l 111 computer. 'l'ht, video disfrlil).uith these ctmputws is Imken into d erid of trlocks. 'l'hr rrid cunllsu 111.18rows nnd 128 columns, fo; a total of 6144 hiocks. These hlocks can he assessed individually. That is, a command can he issued to turn any one of theblocks on or off. We decided to let the bottom 39 rows of hlocks represent reactant molecules: the top 9 rows are used to display-a clock. A block that is off (unlit) represents an unreacted reactant molecule, while a hlock that is on (lit) represents a reacted molecule. As the "reaction" proceeds, the computer randomly selects a hlock of the grid. If the hlock is off, then it is turned on. If the block is already on, then another block is randomly selected. As the "reaction" proceeds, a clock is displayed a t the top of the video display that keeps track of the elapsed time. The computer maintains a running total of the number of hlocks that have been turned on. Thus, as the reaction proceeds, the student can actually observe the reactant mol&ules being consumed. One of the trends that becomes readily obvious from this type of display is that the rate a t which the reactant is consumed decreases as the reaction proceeds. The length of time that the reaction is allowed to run can he varied bv the student in one of two ways: the student can either select the numher of seconds the reaction is to run or the numher of blocks that will be lit when the reaction is complete. The latter method is useful for checking a reaction half-life. When the reaction is complete the number of lit hlocks (reacted molecules) and the elapsed time are stored. The student can then perform another run. When the student has completed a sufficient numher of runs, the elapsed time and the numher of unlit hlocks for each run
