PCM: A physical chemistry monitor for CAI - ACS Publications

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these utilities are important "building blocks" to he used in constructing an effective lesson system. They do not in themselves have much useful purpose to serve outside the lesson systems. Our programs are available free of charge by writing the authors. Some simple modifications will he required to run these on most systems. These modifications are described in the program documentation. At present we run these programs on a PRIME 400, and are m the process of modifying them for a Burroughs B-6800.

PCM ii w acronym: you a r e my boss! Ifyou need guidance enter HELP f o i l a w e d by a c a r r i a g e r e t u r n and my h m i e d vocabulary w i l l be i e u e a l e d . ?help T h i s i s my powerful v o c a b u l a r y - - e n t e r t h e keyword and your c m a n d w i l l b e executed. A l l i t of t h e k e m o r d r f a l l o w e d by a s h o r t e x p l a n a t i o n follaui KEYWORD cOnifanfr units evaluate

refresh test

water end

Acknowledgment

This work was supported, in part, hy grants from the State University of New York Research Foundation, #125-4006B and # 125-4008A.One of us (BDJ) is grateful to Barbara Joshi for her encouragements and unflagging support during the course of this work. We wish to thank Professor John W. Moore, the editor of the Computer Series, for his critical comments and suggestions.

PCM: A Physical Chemistry Monitor for CAI

E n t e r a PCM c m a n d o i HELP.!ionitanir USEFUL CONSTANTS

I cdl 1 eY

4.184 J 1.602e-19 J 9.869e-6 atm = 1 Newton m-2 = 760 torr [m Hg]

1 pascal 1 pascal (Pa) 1 dm

Dwight C. T a r d y University of Iowa Iowa City. IA 52242

Physical chemistry is a subject that involves the application of complex mathematical formulas. The formulas provide a link between macroscopic chemical properties and the fundamental laws of nature. Due to the level of mathematics and the fact that macroscopic quantities are often hidden in non-trivial mathematical equations, the marriage of physical chemistry and computers is obvious. Computer Augmented Instruction, in particular, computers applied to solving problems, provides the student with an "instant" response capability in answering numerical questions. Unfortunately, until recently, computers have been used primarily in the research endeavors of whvsical chemists and not in nrovidine tained iystem (herein named PCM-a Physical Chemistry Monitor) that would present to the student questions (pertinent to physical chemistry) which tie the mathematical and real worlds together. Requirements of the program were such that a formal computer programming language would not he necessary, and new questions could be added to the program without appreciable effort.

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1.602e-19 cauiombr 4 . 8 0 3 ~ - 1 0 eru i speed o f l i g h t 2.998ei8 rn 5-1 h ~ l a n c k ' rc o n s t a n t 6.626e-54 J i N A v o g a d i o ' i Number 6 0 2 2 e 1 2 3 g-mal-1 R U n l v e r i a l Gas c o n i t a n t 8.3144 J mol-1 ti-: 8.2OSe-2 1 37.7 mol-1 1.987 cal n a l - 1 ti-l 1.381e-23 J K-I 9.109e-31 k i 980 cm i e c - 2 2.7182 pi 3.14ik E n t e r a PCM i m a n d or H E L P l u n i r UNITS-CONYERSION FACTORS e l e c t r o n charge

e

10 dynes im-2

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I T m L E OF CONVERSION FACTORS1

0.529 A n 9 i t r o m r 1 a t o m i c u n i t (Bahr o r b i t ) 27.2 eu 1 atomic unit (Hartreel E n t e r a PCM c m a n d or electron i (ELECTRON 15 NOT A N o t a p r o p e r PCM camand. V I i l l D PCM KEYWORD1 E n t e r a PCM c m a n d or HELP.?IEST Available subjects: 1. Thermodynamics

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!8 THE QUESTION> 3. By h a many J o u l e s da.s the intema, energy O f a i y s t e n i n r r e a s * xnpn -13.1061 i a l o r i r i o i n e a t a r e extracted iran t h e i l r t a m -.917614 l l i L l b m O l p h u P I O f *Orb d m added t o t h e nsTaml NO" I n p u t YO"? ""meilcal answer. 1W~L ,GO TO /",A t i t h e r enter the u p i e i i i o n you rant e v a l u a t M o i l i T . TO C3LC"LaTII 'i.+i.,l, 'I' n o t found i n l i i i n c e ' 1 ' ; try a w l "

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Flgure 1. Subprograms of PCM ~ 8 t valid h access paths Double arrow implies aUtOmatlC return.

212

Journal of Chemical E d u c a t i o n

Figure 2. Sample session of PCM; editorial comments (located on right) have been added for further explanation. Upper or lower case entries are valid input.

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The basic PCM program (written in BASIC for the H P 2000 system) allows the student to: i. evaluate mathematical expressions (calculator mode); ii. retrieve tables (physical constants, conversion factors, chemical constants, etc.); iii. refresh the output on the terminal when answering questions asked by the PCM TEST module. PCM is actually an executor; it jumps to subprograms as commands are entered. The seven user available subprograms (entering command is capitalized) are: 1) HELP: produces a listing of validPCM commands with an ex-

planation. 2) END: terminates PCM. 3) UNIT: lists conversion factors that are commonly used; i.e. kcallmole to cm-l, etc.) and automatically returns to calling

program. 4) CONSTANT: provides fundamental constants for chemistry,

necessary if you forgot the questmn!). 6) EVAL: evaluates mathematical expressions (a RET must he entered to return to calling program). While in this mode you may access: UNIT, CONSTANT and REFRESH. 7) TEST: provides exercisesfor the user; it is organized by subject units. Figure 1shows a flow diagram with valid paths to the various routines listed above. PCM provides a question selected hy the user once a subject (Unit Conversions and Mathematical Equations, Thermodynamics, Chemical Kinetics, Quantum Mechanics, and Statistical Thermodynamics) is picked. The question may he assigned hy the instructor. The user can then use any of the resource materials (UNIT,'CONSTANT or REFRESH) in solving the question. If the numerical answer is outside of a certain range it is unacceptable; after a predetermined number of unacceptable responses PCM will provide the underlying equation as a hint. The user can exit and return toPCM a t any time hy entering R E T followed by a carriage return. If a question number is outside of the acceptable range an automatic return to PCM is executed. The execution of EVAL is based on transforming the expression to he evaluated (a character string) into operations and variables. The vocabulary of EVAL is limited to: 1) operators [addition,substraction, multiplication, division, ex-

ponentiation] 2) functions [tangent, sine, cosine, ex, loglor, logex,N!]

3) delimitersl(.)l 4) numbers

Updating or adding new questions is relatively simple. T o add a question the instructor provides: 1 ) the evaluating equation:

2) the variables;these can he randomlypicked by PCM and then

properly sealed to have physical sigmficance; 3) a character string representing the actual question; 41 the aeeeotahle ranee for the answer: 5) a character string representing the 'hint' equation; and 6) the number of responses before the 'hint' is to appear.

The ahove input requires a minimum of effort on the instructor's vart and allows tailorine the svstem for emphasis on partic& material which can change from year to Gear or instructor to instructor. Bv us in^ random variables the correct answer will change for different users. A real time program execution, illustrating some of the capabilities of PCM, is depicted in Figure 2. Editorial comments have heen added to provide an explanation when necessary. Although a specific computer program has been generally discussed, general concepts such as a screen refresh and the evaluation capahilities can be generally useful in any CAI program. An underlying principle in this work is to minimize the amount of material given to the studenl; i.e. the user must use references provided in PCM generated Tables (units, constants). The design is such that the instructor can easily add questions to the program. A copy of the listing for the PCM program, written in BASIC is available from the author. Acknowledgment

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The author ereatlv aonreciated a Summer fellows hi^ from .. the Universityof Iowa and computer time provided by t h e U of I Graduate College a t the Weeg Computing Center. Literature Cited (1) Eilers, J. E. and J0shi.B. D., "Qumttm ~ h h h i i t & E x p ~ ~ i mSy~tem..' iit SiithBiiiiid Chemical Ed. Conf., Rochester InstituteofTechnolnyr, Rachester, NY. June 22-26,

1980. (2) Eilera, J. E., Cronin. L a n d JoshiB. D., "ACalculator Made forlnteractive FORTRAN CAI.))TenihNortheast RegionalMeotingof the Am. Chem. Soe.,Clarkarm College. Potidam. NY. June 3 M u l y 3. 1980. (3) Joshi, B.D.and Eilers, J. E.. "Quantum Chemistry Instructional Packare Using in^ teradive FORTRAN.)) R o c . Noti Ed-. Computing Conf., TheUnk. of 1 0 ~ 866 9 1 ,707m3 ,A",",.

.

ldi Lower. S.. Gerhuld. G.. Smith.3. . G.. J0hnson.K. JLandMwre. J.W..J.CHEM.EDUC.. 56, 219 (19791.

(5) The importance of solving problems in understanding the underlying concepts are described inthis very engaging hook by Polys, G.,"How to Solve It.)) Doubleday & Co., GardenCity,NY, 1957. (6) Sherwond, B. A,, ''The TUTOR Language," Computer Based Education Research ~ ~ f universityofniinuis, i ~ ~ ~ t urhana. ~ ~ 1974. ~ , (7) Polivka, R. P . and Pakin. S., "APL: TheLenguage and Its Usage.))Prentice-Hall,Ine., Englewood Cliffs, NJ, 1975. (8) Ral1.J. A.,"Algo~ithmsfor RPN Calculators," John Wiley & Sons, New Yo& (19781, "" Fp 9.q (9) Smilh, J. M., '"ScientiEicAnalysis on the Pocket Calcuiaior.))John Wiley & Sons, New

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Vnrk , 1 7.~ 6~ ... ., ~.

(10) "Advanced Calculafur Logic: Herlett-Packard RPN and Algebraic Notation-A Cumgsrstive Analysis..' Hewletf~PackardCo., Form 5930~1930,Palo Alto. CA, 1979..

Volume 59

Number 3

March 1982

213