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Cynthia J. Jameson UniverslIy of Illinois at Chicago Circle Chicago, Illinois 60680
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Computer-Enriched Modules for Introductory Chemistry
While there has been a h e volume of computer-based instructional material p r o d u d over the past fewyeara, it has been found that these materials are essentially immobile. In addition to the transport implementation tasks of software conversion for local use and debugging, there is the major diffindtv,of lack of technical and educational - - ~ documentation ~ documentation. In this project (Computer-Enriched Modules). we- tackle the nroblems of transoortabilitv a t the outset and develop modules which have a high degree of transportability. This effort is a collaboration of several chemistry teachers from small colleges and large universities and is part of a larger effort including the related areas of mathematics and physics. The topics included in these educational materials are tooics in the mainstream of introductow chemistry for majors or nonmajors. The structure is modular, consisting of units which can be but need not he used together to form a nlhesive whole. Documentation is provided for both student and teacher u, ease the implementation at other institutions. No student programming is required and the computer programs are relatively simple and short as to be useful in schools with modest computing facilities. A module is made up of one or more units. Each unit has (1) one or more computer programs, (2) a student manual, and (3)a teacher's guide. Each unit is self-contained and may be used individually or with the other units in the module. Each one is meant to be a first-exposure self-study unit. A list of available modules is shown in Table 1. Modular Appendices are atudent manuals which provide needed background for some units. wbich do not necessarilv have a computer . p r. o m associated'with them. Each unit requires active ~articipationby the student. He has to answer questions, sol;e problems, &d interact with a c o m ~ u t e r .Each unit is suitable for any of the following ~~~~
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1) as a first-expmure,self-study unit 2) as an adjunct to traditional lectures 3) as a workbwk or problems book for students having difficulties
with prablem-solvingskills 4) in some eases, as a review for a post-introductory course or as a review of earlier material for the later part of the intmductory C olll~e ..-~.~
5) as the study guide for a unit in a self-paced course
For maximum effectiveness. it is recommended in some units that they be used before many lectureson thesubject are given. The empirical approach is used here and it is desirable for the student to "discover" a phenomenon or a general rule before it is sostated, in order to avoid a feeling of dejd uu on the part of the student. In a self-paced plan the student manuals provide clearly stated objectives, and the problem sets at theendof the manual test the mastery oftheseobjectives. In addition, the unit tests and their answers provided in the teacher's guide make the adoption of these modules for a self-paced plan practically -painless. The Studant Manuals Each student manual contains the followine: obiectives. ~. prerequisites, pre-test and answers, introduction, discussion with exercises, and problem sets. Since the performance objectives for the student are clearly stated (i.e., when a student finishes the unit, what will he be able to do?), the student knows what the goals of the unit are. T h e prerequisites state what the student has to know before attempting the unit. In case he has any doubts, the pre-test ~
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238 1 Jownal of Chemical Education
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provides him with a way of determining whether he is ready for it. There are a large number of sample problems with complete solutions provided within the discussion, as well as unsolved problems for self-study. The answers to the latter are provided in the teacher's guide. I n addition to these problems which are a n integral part of the unit there are 20 problem sets provided a t the end of the student manual from which the instructor may choose, if he desires, one or two problem sets to assign &homework for the class to do. T h e large number of problem sets provided allows the instructor to give different assignments to different sections running concurrently or a different assignment in each succeeding term that the course is taught. T h e student manuals are machine-independent since no Table 1. Topio i n Which Modules May be Ured Lecture TOPIC
Text Chap. Sec
Module/ unif
Introduction Measurements, rlgnlflcant figurer and unit convcrslonr Atomic theory. - . comoonentr of atoms
Stoiehiomerry
~ t o m i cweight, Avogadro'r number. molecular Weight SlmDlert formula, molecular formula. the mole Interpretation of balanced e m . theoretical yield, percent yield
Electronic Stmerure and Bonding PBrlodlC law and electronic structures of elements Ionic and covalent bonding Molecular geometry
Thcrmodynllmics Flrrt law. AH second law, AG. AS Gases, Liquids and Solids Behavior of gases crystal structure Li9uId-~aporequilibria, phase diagrams
1.2
A1. A 2
2.1-2.2
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2.4-2.6 3.1-3.3
none
Chap 6 and 7
none
Chap 4 chap 1 2
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chap 5 9.3 9.2--9.4
none C2
Solutions introduction to solutions, concentration units C ~ l l i g a t i ~Properties e
Chemical Equilibrium Concept of K , form of K APDiicatlonS of K , calculatlonS In galeOUs system.
Le Chatelier'r principle
Chemicol Kinetics Reaction rater and concentrations Reaction rater and temperature Rate ecluationr and mechanisms
Precipirotion Equilibria Ionic eauationr soiubility of ionic compounds The ~ o i u a i l l t yproduct, calculatlonn
Acids and bases
Di610' Di6loclation o f water. pH, strong acids and bases Bronrted-Lowry conced Wesk acids and weak barer Reactions of rtrong acid +weak base or weak acid + rtrong base Buffer6 A&-bars titrations Normality. equivalent weights
17.1-17.3 17.7
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18.3 18.2
D4
20.1-20.2
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Oxidation-Reduction and Eleerrcchemistry
oxidation numbers, baianclng of redox eqns Electrolytic ceitr and voltaic cells Standard potentials Of concentration On
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program listings or printed output are shown in them. They a r e a l s o textbook &dependmi. The student manuals are sufficiently complete that the student will be able to fulfill the objectives stated for the unit without having to consult an external source for definitions and such. The manuals serve as workbooks for the student. T h e detailed solutions to example problems and the large number of unsolved problems for self-study provide him with a way of acquiring and refming problem solving skills. take an active The student who uses these modules has to ~. role. The programs are interactive and require a contribution on the Dart of the student. In the student manual he is constantly iequired to answer questions, fill in intermediate steps, and enter computer results. The Teacher's Guldes The teacher's euides contain educational ohiectives. implementation, answers to prohlems, and software. In the educational obiectives of the unit he.. what is the unit attempting to Gach or do?), there i s a discussion of the pedagogical approach, the strategv ~ l o- v e din develooine the ..- e m. concept& the route taken in solving the prohlems..~Ggestiona for implementation include a discussion of how much prior knowledge is required of the student, how much student time the unit will take, and how much computer connect time. Answen (and sometimes detailed solutions) to all the required problems, and answers to all the problem sets are given. The software section discusses core and disk storage requirements of the programs and any special functions which are not standard on all computers. The program(s) are described, the listing of the source program and a sample output showing a typical exchange between a student and the comouter are &en. Exams which teat mastery of the unit, and the; answers are also provided in the teacher's w i d e for ease of adootion of these modules in self-paced cou&es. The Computer Programs1 The programs are of various types, nearly all interactive. There are simulations such as EQSIM and LECHAT; and games such as ENDPT. Some are self-test generating proerams such as CTEST. EQUIZ. and COLLIG. There are those which are used for comparison of exact calculations with approximations, such as ACID. T h e trial and error approach is used in EQUIL and EQCALC. Numerical demonstrations or "discovery" of basic principles are carried out in HETERO, BUFFER, ACID, KEQ, EQSIM, and LECHAT. DILUTE is a diagnostic program (diagnoses student errors). These programs are not the conventional CAI type. Each of the programs are available in Basic, are typically 100-200 statements long, typically require 2-3 K of disk storage. The smallest program requires 256 words of core to run; the largest program requires 10 K of core to run. The programs are currently implemented on a P D P 11/45 (16 K ) and a HP-2000 (16 K) as well as on a HP 3000. The computer program which generated the problem sets in the student manuals and the unit tests in the teacher's guides is a large prohlem-generating program written in PL/I which uses numerical and string-handling algorithms to create problems and their answers. chemical f&n-& are coded for printing on a high-speed printer equipped with a special print chain for upper and lower case letters as well as superscripts and subscripts. The Team The programs and manuals were written by teachers from several schools working together during summers and national meetings
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'Computer programming references for an instructor or his motivated students interested in writing their own programs to accompany these units are: Soltzberg,L., Shah, A. A., Saber,J. C.,andCanty, E. T., "BASIC and Chemistry," Houghton Mifflin, Boston, 1975; Wilkins, C. L., Klopfenstein, C. E., Isenhour, T.L., Jurs, P. C., "Introduction to Computer Programming far Chemists-BASIC Version," Allen and Bacon, Boston, 1974.
Morris Bader, Moravian College, Bethlehem, Pa. A. Keith Jameson,Loyola University, Chicago, Illinois Cynthia J. Jamesan, University of Illinois at Chicago Circle (Coordinator and Editor) Chicago, Illinois John J. Manock, Western Carolina University, Cullowhee, North Carolina Richard T. O'Neill, Xavier University, Cincinnati, Ohio Frank Settle, Virginia Military Institute, Lexington, Virginia Robert C. Williams, formerly at University of Nebraska, Lincoln, Nebraska. Abstracts of Completed Unlts MWule on Stoichiometry
Unit 1. "The Mole Concept," by R. Williams-The unit deals with problems involving the mole concept, elemental compasition, and determination of empirical formulas. MOLE generates unique exams of five questions for eachstudent to be taken swav and solved. The student returns to the terminal for checking of his answers. This program uses the logic and algorithms of C E S T Appendtces "Exponential Numbers w d Logarithms" and "Use dConvemi~nFacto~j"provide prerequisites to this unit. Unit 2. "Solving Stoichiometry Problems," hy R. Williams-This provide; problem-solving practice on simple stoiehiometry problems,limiting reagent, and percent yield problems. Like MOLE, ST01 and ST02 make extensive use of the RND function of Basic to ensure that individuallygenerated exams are different. M e on Gases, Liquids, and Solids Unit 2. "Phase Equilibria," by M. Bader-This unit discusses the phase diagram of water, primarily, and provides the needed prerequisite to the unit on colligative properties. Very interesting layman's examples (dew, fog, ice-skating)are used to illustrate phase equilibria. A quantitative section on the Clausius-Clapeyron equation may be included at the discretion of the instructor. (Unit 1on Behavior of Gases is in preparation.) Modole on Solutions Unit 1. "Introduction to Solutions. Weight Percent, Volume Percent and PPM," hy M. Bader-As a first introduction to concentration units, weight percent, volume percent, and PPM are easily mastered. The testing of these concepts is postponed until the student has completed other concentration units. Unit 2. "Molarity, Molality and Concentration Conversions," by M. Bader-CTEST is a 2-pass quiz program. The first pass generates a quiz which a student takes off-line.In the second pass the student enters his answers and the program grades them. This is based on the use of a random number generator which is seeded by the clock. The seed is printed out as the quiz code number. This seed is used in the second pass to regenerate the answers to the same quiz. Unit 3. "Dilution Problems," by R. T. O'Neill-This uses a tutorial program DnUTE which diagnoses student errors in setting up dilution problems. Unit4. "Solution Stoichiometry," by R. T. O'Neill-Program ENDPT uses a came format to discover the volume of a strong base of known molarity needed to exactly neutralize an aliouot of acid of known concentration, This oroeram .. prepares the student for his initial exposme to laboratory titration using an indicator-determined endpoint. Thra unit is in twoparb, the seuund part which may be portponedim later treatment involves problems in terns of equivalentsand normality. This unit does not assume a background in acidbase or redox reactions, merely that two reagents react in a chemical equation. Unit 5. "Collieative Prowrties of Solutions." bv M. Bader-COLLIG generaws quia~esw~thprohlems on Haoult's law, lowering uf vapor pressure, elevation of boiling point, depression of freeling point, and usmotic pressure. The unit on Phase Equilibria or its equivalent is a necessary prerequisite.
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Module on Chemlcal Equilibrium
Unit 1. "Introduction to ChemicalEquilibrium,"by J. Manock-This uses two oroerams which allow the student to "discover" . .. chemical equilibrium and the equilibrium constant. Program KQSIM leads to the discovery of rhem~ralequillhrium hy a simulation ufasystern,A = H C, which starts with pureA and comes to equilibrium. A sequence of pictures shows the
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Volume 54. Number 4. April 1977 1 299
random positions of gaseous molecules A, B, and C at the times chosen by the student. It shows that equilibrium is dynamic, not static. It portrays the relationship hetween numbers of molecules of each kind: the student can count them. Then the equilibrium is approached from the B + C side. Program KEQ is an the discovery of the functional fom of the constant of equilibrium. The program gives simulated equilibrium concentration data for various initial conditions, and allows thestudent toinput his choice of combination of concentration terms until he finds one which is a function invariant with respect to initial conditions. The first example is the simple A = B + C, the second one is A = 2B. The emphasis of the module is for the student to he led to a quantitative understanding of an equilibrium expression through the exciting mode of diseouery. Unit 2. "Le Chatelier's Principle," by A. K. Jameson-LECHATis a simulation of a chemical swtem in eauilibrium bv teletwe .. graphics. Stress may be applied on th~syrtemby thestudent in the form ofaddition of reactantsor products,or changing pressure. The program simulates huw the Jystem reacts. showing before and after pictures. Unit 3. "Chemd Equilibrium Calculntmns," by C. J. Jameson-The proaram EQUIL allows the student to find equilibrium . . concentrations by a trial and error approach, using a comparison of the value of the reaction quotient with the equilibrium constant at eachstage. The student has to choose the direction in which the reaction has to go in order to get to the equilibrium state. The student manual shows algebraic methods of solving problems. The program EQCALC uses the same approach on the student's own choice of reaction and initial conditions on systems too difficult to do algebraicallv because thev involve hieh-order oolvnomial eaua. . tions. I'rogram EQIIIZ is a 2-pass quiz-genrratmgprogram which uses a random selection ofsyxtemu and data, and on second pass, given the quizcode number, will print only the answers to any quiz. Unit 4. "Equilibria in Acid-Base Systems," by F. Settle-This unit uses two programs to explore acid-base equilibria. In ACID the student will (1) discover how DHand deareeof dissociation changes with &dytiwJ conkntration of an acid or base and (2) find limits of applicability of an approximation commonly used. The student does hand calculations using a simplifying approximation and compares with the exact calculationsdone by the program. In BUFFER he discovers how a buffer system reacts to the addition of small amounts of strong acid or base. The student inputs such changes, the program does the calculation of pH. This is otherwise very time-consuming to demonstrate hy the lectwe method. Appendices "pH" and "Exponential Numbers and Logarithms" provide prerequisites to this unit. Unit 5. "Heterogeneous Ionic Equilibria," hy J. Manoek-HETERO is a numerical demonstration of the constancy of the solubility product and its lack of dependence on the amount of solid present. Precipitation problems arranged in increasing complexity are illustrated in the student manual. Mwular Appendices Unit 1. "Exponential Numbers and 1.ogarithms." by C. J. Jameson-This unit shows how a number may be written in exponentis! notation and how mathematical operations involving numbers written in exponential notation are carried out. Logarithms and antilogarithms are defined and their use illustrated with many examples. This unit serves as a prerequisite to many later units. Unit 2. "Use of Conversion Factors," by R. Williams-This unit shows the importance of units and introduces the method of dimensional analysis in solving problems. The program UNITS tests him on problems using conversion factors. Unit 3. "pH, Strong Acids and Bases," by F. Settle-This unit deals with the ionization of pure water, the introduction ofpH and the Bronsted-Lowryconcept of acids and bases. The calculation of pH from known H30+ are OH- concentrations is also shown with many illustrative problems. Curriculum Guide to the Use of Computer-Enhanced Modules A typical introdurtory chemistry course includes the topics listed inTahlc 1 in which these mmules may be used. Chapter and section numbers in a commonly used textbook by Masterton and Slowinski are cited for cross-reference. The modules 240 / Jourml of Chemical Education
Table 2. Computer-EnhaneedModulesfor Freshman Chemistry A. M O D U L A R APPENDICES 1. Exponential Numberrand Logarithms 2. use of conversion Factors 3. pH, Strong Acids a n d Barer B. M O D U L E O N STOICHIOMETRY
I . The Mole Concept
2. s o l v i n g Stoichiometry Problems C. MODULE O N GASES. LIQUIDS A N D SOLIDS 2. Phase Equilibria (unit 1 being written, on Behavior of Gases) D. MODULE O N S O L U T I O N S 1. Introduction to Solution.; Weight Percent. Volume
a n d PPM
R.
~olarity,Molality. and concentration Conversions nilution Problems
5.
~iterogeneourionic Equilibria
2.
Percent
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and units are denoted bv letters and numbers corres~ondine to Table 2. Asterisks denote modules in preparatioi. There are no modules planned for the topica in "descriptive chemistry" (organic chemistry, coordination compounds, biochemistrv. the nonmetals. metals). There are also some concepts not included in the present modules 1) Sienifieant firmres are not discussed in the unit on the use of " convenion . .~ ~- ~ - factors - ~ ~ ~ 2) K, and the relation between AG and K are not discussed in the chemical equilibrium module. 3) Curves of pH versus volume of titrant are not discussed in the unit on equilibria in acid-basesystemsalthoughthestudent gets a sufficie&ly thorough treatment of pH calculationsin this unit that he can calculate titration curves if asked to. 4) Activities are not discussed in any of the mudules. While there are these omissions from a complete textbook coverage, there are also some special strengths: (a) The treatment of problem-solving in the areas covered by the modules is more detailed and complete than is normally found in textbooks. T h e number of illustrated problems and the problems made available to the student in the form of problem sets are much greater than found in problem books. (h) The empirical approach and the mode of "learning by discovery" used in the modules is different from the usual ones. This is especially enhanced by the interactive nature of most of the computer programs used here. These modules are not yet available commercially; however, a limited supply of the written materials has been printed and distributed to interested individuals. A complete set of the written materials can be obtained from CM Project, H. Weinstock, Physics Department, Illinois Institute of Technology, Chicago, Illinois 60616, free of charge a s the supply lasts, or a t a minimal cost thereafter. Some modules have been used by students in courses a t Moravian College, Western Carolina University, Loyola University, and University of Illinois a t Chicago Circle. T h e complete set of modules has been used in courses at Virginia Military Institute and Xavier University. All the programs are implemented on an HP3000 and also on a PDP-11/45 system. In addition, some programs have working versions on an HP2000, a PDP-SF. and an IBM 1130. ~~~~~~
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Note Added in Proof The followingadditional modules are now available: Appendix 4. Naming dChemiral Compounds, by A. K. Jameson Module un Atomic Structure: The Nuclear Atom, by A. K. .lameson Module on Gases, Liquids and Solids: Unit 1. P-V-T Behavior of Gases, by C. Jameson Module on Redox and Electrochemistry: Unit 1. Oxidation Number and Balancing Redox Equations, by R. T. O'NeiU Unit 2. Electrolysis, by M. Bader Module on Chemical Kinetics: by F. Settle and J. Manock Unit 1. Reaction Rates and Routes Unit 2. Effect of Temperature and Catalyst on Reaction Rate
Acknowledgment
This project is a part of Computer-Enriched Modules in Chemistry, Mathematics, and Physics which is supported by the National Science Foundation and Exxon Educational
Foundation. Computing serviceswere made available by each of the computer centers of our home institutions. The use of an HP3000 was also provided at Illinois Institute of Technology by Hewlett-Packard.
VOlWne 54, Number 4. Apll
1977 1 241
