Chemistry: Sloichlometry Chemistry: Aclds a n d B a s e s J. Frazin and partners, Encyclopedia Britannica Educational Corp., 425 N. Michigan Ave.. Chicago. IL 60611. Hardware: Apple II family Software: DOS 3.3 Components: One disk and manual for each Level and Subject: High school chemistry Cosl: $59 Revfew I These twodisks contain drill and practice programs suitable for beginning students of chemistry in high school or perhaps college. Each comes with an imoressive folder eonmining 12 pagrs of documentation whwh d c w r i k s the nature of the drills with wrne examples and essential tahies. Upon bwt;ny the disks, a statement appears warning against duplication, and to encourage compliance the contents cannot be copied nor listed directly. This is unfortunate because the programs constantly access the disk so that a coo", will have to he ourchased for each CumputQrroncurrentiy in use. A call to the publisher determined that there war nu set policy with respect to the purrhnse uf multiple copies. A backup copy ordered with the initial purchase is $10, h u t a suggestion that my school acquire further copies at a reduced rate, resulted in referral to the computer section. This reviewer did not pursue the inquiry. After the warning, which is timed and difficult to comprehend completely in the allotted interval, several screens of directions for entry of answers is shown. Each is short a n d clear. T h e s t y l e of p r e s e n t a t i o n throughout is similar to that recommended by Burke (1) and the result is more like a slide show than a dynamic display. The lettering is large and the screens uncluttered. I t is possible to confuse the letter 0 with zero--"Choose Entry level, 0 = End9'-but not where it mattered in the body of the program. An option to omit the directions before each drill would have saved much time for reoeat users.
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swer displayed. This was the major grievance of the student user. Over half of them complained that they needed mare direction after an error. There is some adjustment according to student errors in that three wrong answers in a row moves students to a lower problem level for practice, and three consecutive correct answers moves them up a level if possible. Stoiehiametry gives drills on Formulas, Equations, and Male Concepts. Those on writing formulas and balancing equations were unexceptional. There are no redox equations to halance and a drill on calculating formula weights could well he added. The quantitative relationships implicit in balanced equations is contained in the Male Concept section. A Periodic Table and a hand calculator are needed for this part. There are some hints in this section, generally in the form of a question. For example, "Did you use a molecular mass of 18 for H20? 1 = YES 2 = NO". These are useful hints but a better input routine would have accepted "YES" or "Y" in addition to "1" for an affirmative answer. This disk was made available to students in the first chemistry course far non-majors. The population is chiefly pre-nursing students with no previous chemistry experience. Written opinions were solicited. The
There are two ways to enter data from the keyboard. When nan-numerical entries are expected, single letter choices are offered. RETURN is not necessary but there is a short pause during which the entry can be corrected. Periods appear at one second intervals during the pause so that the user can he certain that the computer is functioning. This appears effective-nly one student expressed difficulty with it. There is a "beep" after the acceptance of an entry and the ability to turn it off would have been welcomed. For numerical input, a cursor appears where each digit of an entry is to be placed. If a three-digit entry is expected, the cursor cycles through each position but accepts complete input only after RETURN. This procedure leaves little room for error while allowing ample opportunity to correct entries. Impatient students could have problems with an entry like 4.18. They enter that number without noticing that the computer supplies the decimal point. However, they soon learn to adjust. These programs are drill and practice with little tutorial function. No analysis of student errors is attempted and no records are kept of student scores. The answer is either right and a variety of short compliments is given, or the answer is wrong and, with an occasional exception, the correct an-
Summary Ratlngs: Re"I0w.r
I
Category Ease ofUse Subject ~ a n e content r Pedagogic Value Student Reaction
Stolchlometry Very Good
Average Average Average
Ackb 6 B
w
Gwd Pwr
Average N/A
Owr.11 Very Gwd Average Average Average
Category Gwd
Ease of Use Subject Marter Conten1
Average Average Average
Pedagogic Value Studenf Reaction
--Reviewed In This Issue Computer Learning Packages
Reviewer
J. Frazin and partners, Chernistry: Stoichiometry; Chemistry:
Victor I. Bendall Robert Roe. Jr. Stanley R. Watkins William D. Krugh
A202
Richard A. Paselk George B. Kauffman
A208 A209
Acids and B a s e s F. P. Rinehart, The Chernistry Tutor
A206
Books K. E. van Holde, Physical Biochemistry, Second Edition Bassam 2. Shakhashiri, Chemical Demonstrations: A Handbook
for Teachers of
A204
Chemistry, Volume 2
Journal of Chemlcal Education
results were generally favorable hut seldom enthusiastic. For example-"I liked it tremendously"; "I think it was fun and it was alsogood practice"; "I like the idea of having computer exercises to reinforce Lecture concepts, (but) trash this particular program"; "I think that it would help if there was a way to look at a periodic chart on the screen"; "I didn'tunderstand why I was getting some of the answers wrong"; "Ifeel that the program should have an example of each particular problemlquestion and show how the answer was obtained". Acids and Bases has drills on Acid-Base equilibria, Equilibria of Water-K, and a Titration Simulation where the concentration of a base can he calculated using data acquired hy the user. This simulation is the only animated graphic contained in these software packages. The lower half of a huret is displayed and, by pressing the space bar, increments of standard hydrochloric acid are added to a beaker containing a known volume of sodium hydroxide of unknown concentration. At the end point the solution turns "pink-alternate magenta and white lines-and then red. The latter condition generates a warning that too much acid has been added. An enlarged view of the liquid level in the buret can be displayed a t any time. The concentration of the hase is requested and the value and accuracy of the result assessed. The simulation is disappointing. The huret stopcock is not easy to see against the blue background. Its position, open or shut, is controlled by the space bar and is drawn slowly. During the early part of the titration, the liquid level was not on the screen so that the buret appeared empty even as acid fell from the stopcock. Yes,dilute hydrochloric acid is transparent but if this is the reason for the display of an apparently empty huret, why is the hase solution white? The instructions never told the user that a colorless (white) to pink change would occur a t the end point. Indeed, this is the reverse of common practice where the usual phenolphthalein indicator gives a pink color with excess base. At the start of the titration, the liquid level is set to 0.00 ml (sic). This is poor practice. The numbers on the buret are poorly drawn and the enlarged meniscus is difficult to see. There is a significant interval between removing the fingers from the R E P T and SPACE keys (fast addition mode) and the cessation of liquid flow. Students expect, and should get, better quality graphics from a commercial product. The Acids and Bases disk was made available to the students for a few hours but was quickly withdrawn with the fervent hope that noneofthem had investigated thedrills on Equilibria in Water-K,. These drills are based upon a common student error. A typical question was "What is the pH of a 1 X 10-lo molar solution of KOH?" The "correct" answer was 4.0! Seven of eight successive problems gave similar answers. Drills which asked for the hydrogen ion eoncentration of dilute hase solutions argued that they were acidic also. The most feared error of a CAI programmer is one of subject matter. Such errors can arise from several sources. There may he a transcription error as the code is entered into the computer or the algorithm used to generate random prohlems may be flawed and give spurious results under special unanticipated circumstances. Finally, the au-
thor may have introduced his own misconceptions into the program. This software cannot he listed and without a listing the probable cause of the error in this program can be neitherjudged nor corrected. Nevertheless, an error of this magnitude should have been corrected before the disk was marketed. Drill and Practice programs are the easiest of CAI software to author hut the most difficult to write well. These oartieular examoles of the eenre make o& use of the rumputer. There rs little tuturial function and analgsir irf student errors. There i~ no recurd-keeping so feedbark to the instructor of student errors cannot be obtained. At one time the novelty of using a computer was enough to carry the simple drill and practice program but those days are gone. Chemistry is a dynamic, exciting discipline and there should be at least some effort bv software vrndors to communirnra that to students. The imagr of the Encyclnpa~diaBrittnnira is of facts presented in a bland, boring way. This software does little to dispel that pieture. Burke, Robert L. "CAI Sourcehook"; Prentice-Hall Inc., 1982. Vlctor I. Bendall Eastern Kentucky University Richmond. KY 40475
Revlew II These programs are intended for drill and practice and would he suitable for students who have been introduced to these topics. The Level is most appropriate for chemistry honors students and students who are taking a second year of general chemistry in high school. The programs can he used for practice in the normal classroom provided suitable monitors are available. The documentation is needed only for ohtaining atomic masses, dissociation constants, and logarithms (if a calculator without the log function were used). The content of each program is clearly explained by the documentation. The only omission noted in the documentation was in the treatment of polyprotic acids and very dilute acid and base solutions. No worksheets or other guides are included in the documentation. The information needed for salving prohlems can he found quickly and easily in the documentation or practically any chemistry text. Three chemistry teachers, ten first-year high school chemistry students, and three second-year high school chemistry students ran all of the programs. None of these individuals had any difficultv in usine the nrograms. The programs & complekly menu driven and reouire no more than turnine on t h computer ~ and typing a simple rerpzmse. Thereare nosperisleffec~~. The user simply supplies a "yes". "no", or a cmnputed re. sponse. The prompts are unambiguous and easy to use. In most of the programs, the user can easily skip sections, exit the programs, or go to other programs.
The handling of errors is well done. When incorrect numericalentries or entries having the incorrect number of significant figures are made, the student is given the apportunit" to enter the correct resoonse orovided thnt the return key has not heen used. The inputs nre checked and correct responses given for incorrect ones. The programs do not provide a sufficient numher of remedial prompts. These programs are not flexible in their present format. No instructions are given that enable the user to list or modify the programs. With respect to specific subject matter content, these programs are limited. "Stoichiometry" consists of programs on formulas, equations, and mole concepts. The program "Formulas", consists of subprograms on interpreting chemical formulas and on writing chemical formulas. The student simolv suoolies the correct number of atoms or formula units. The student re~pondrto the prompts until three ronweutlve questions are answered correctly or an 80% success level is achieved. At this point, the program moves to the next program or to the main menu. The program, "Equations", consists of subprograms on selecting balanced eauations and on halancine- eaua. tions. The student enters the coeffirirnt for the number of tbrmula unirb. When errors nrr madr and the return key depressed, the correct responses are given. The student is not given the opportunity to try far a correct response. The program, "Mole Concepts", consists of suhprograms an hasic skills practice and complex problem solving. The "Basic Skills" unit is further divided into suhprograms on gram-mole eonversrona, mdea m equations, thermal equatims, and molar volumes. These programs require the student to use a table of atomic masses and a calculator. The program does not allow the use of the computer as a calculator. The "Complex Prohlem-Solving Program" involves makine conversions involvine masses of rractant.; and produm, volumes of gases. moles of rrarlanrs and products, and the heats ot reactions from balanrrd chemical equations. Some prompting is given when incorrect responses are given, and the student is allowed an opportunity to give a correct response. "Acids and Bases" consists of three programs on AeidiBase Equilibria, Equilihrium of Water-K,, and Titration Simulation. The program, "Aeid/Base Equilihria", eonsists of four subprograms: "Equilibrium Equations", "Calculating Dissociation Constants of Weak Acids and Hydronium Ian Concentrations", "Calculating pH", and "Buffers". The "Equilibrium Equations" subprogram requires the student to give a "yes", "no", or "undecided" response to a proposed mass law expression. T o a response of "undecided", the program displays another expression. An error in the expression for the dissociation of H2P04was noted in this subprogram. The subprogram on calculating dissociation constants ofweak acids and hydronium ion concentrations requires the student to find either the KAor the equilibrium [Ht] given the other
Volume 63
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(Continued on poge A206) Number 8
August 1986
A205
quantity and the initial acid concentration. Only the first ionization of polyprotic acids are considered. The subprogram on calculating KAand pH is very similar to the program on KA and [H+] except that it uses logarithms. The subprogram on buffers reouires the student to calculate lHtl for a buffered aolutmnafn weakacld at equrllhri. um grven the rnrtial numlms uf mules of the aesk arid and its salt, the volume of the solution, and the dissociation constant of the weak acid. The program, "Equilibrium of WaterK,", consists of subprograms on finding the lH+l and [OH-1.,.findine nH.. and findine nH , uring log t a b l e These subprograms are in ei~cntiallythe same format ds the program. ",\cidMa~e Equilibria". The dtudent calculates the [Ht], [OH-], or p H for strong acids and bases. Several errors were noted in these problems involving the calculation of the pH of verydilute NaOH solutions. Failing to take into account the autopropolysis of water leads to the erroneous conclusion that a very dilute rolutim of NaOH would have an acidic pH. r\ddithtnally, w m e ubjection must be made to conridering only the first ionization of diprotic acids in computing [Ht], [OH-], or pH. The nroeram. "Titration Simulation". involves t h h i t r a t i o n of a NaOH so~utiohof unknown concentration by titrating with standard HC1. The student is given a choice of three concentrations of standard HC1. After selecting the concentration of standard HCl, the user sees a buret and beaker on the screen and depresses the "R" key to obtain the initial buret reading. T o start the titration. the "T" kev is deoressed. and the mace bar is used to opernte'the huret. ks thhend puint ir appnmched, the indirstur r h w a more and more color spread with each successive drop of titrant. If the HC1 selected ia too dilute, the titration can be done again using a more concentrated HCI solution. The "R"key and the level of total solution in the beaker are used to monitor the amount of titrant added. Once the end point is reached, the final buret reading is taken, and the concentration of the unknown NaOH solution is calculated. The percent error is displayed, and an opportunity for doing another titration is given. Students liked the titration simulation and considered it very well done. With the exceotion of the titration simulation, these programs hring nuthing new or better tu drill and practice in stuichiometry and acids and bases. These programs are no substitute for the drill and practice that a student can obtain by working a series of problems and recording each step so that errors in reasoning and problem solving can be detected. The students who used these oromam8 were firat.yenr honorr chemistry students who had just finrshed their study of acids and bases and seeond-year chemistry atudents. The students considered the stoiehiametry program on complex problem salving and the acidbase program on buffers and titration simulation useful. These students.
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for the most part, were not motivated by using the other programs. Aiter working with thr first fewsubprog.rams,thestudenrs progressed rapidly through the others. The timi required f i r the siowest student to complete both programs was three hours, while the fastest student took around oneand-a-half hours. The average time required was around two hours. Most of the students worked efficiently through each program and did not require any help from their instructor. Mast of the students and instructors felt that the programs did not have enough variety and were too narrow in scone. ?he recommendation that I would make tot he producer of these programs is that the scope be broadened to ineludp a greater variety of topics and more challenging prohlems. Some minor changes should be made to correct the errors noted. The programs are very easy to use, and it is relatively easy t o move through the menus. The error messages are adequate, and the problems are randomly generated. The displays are easy to read and can he seen easily if a sufficiently large monitor is used. The problems do serve as drill and practice and require some interaction. Robert Roe, Jr. Highland Park High School Dallas. TX 75205
The Chemistry Tutor F. P. Rinehart, Wiley Educational Software 1 Wiley Drive, Somerset. NJ 08873
Hardware Aoole I1 familv Sonware: DOS 3.3 Components: Two disks, manual Level and Subled: Stoichiometry in general chemistry Cost: $30 (Institutional package), $10 (Student package) Revlew I "The Chemistry Tutor" is a two-disk package. The first, called the Tutorial disk, contains three programs which introduce
the student to the methods of balancing equations and solving stoichiometric calculations. The first program within the Tutorial disk teaches the balancing of equations by inspection. Simple stoichiometry and limiting reagents are the other two programs. The user determines the mass of a t or formed when reactant or ~ r o d u e used given thernassofrheorher reartant or pmduct. The user develops skills in halancing equations, calculating formula weights, ealculating moles from grams and the use of coefficients from the balanced equation to determine the mole ratio of reactants and products. The program would be suitable for use for most students a t the high school level, for introductory college chemistry courses and for students in general college level courses needing remedial drill. The programs could be used after the mole concept, formula weights, and the basic concepts of atom and mole relationships in chemical reactions had been introduced in the class. A second disk, called a Utility disk, is to be used by the instructor to write additional equations, to delete equations from the pool and to classify the equations as "hard" or "easy." The equations on the Utility disk can then he transferred to the Tutorial disk. The Utility disk is menu driven and requires no programming skills by the instructor. There is no option for modifying the stoichiometry problems. Five short pages of program description and instructions are furnished with the disks. However, all necessary instructions after hooting the disk are furnished in a general table of contents and in the table of contents of each program. No additional documentation or workbook is needed or furnished. Knowledee " of comnuters is not necr>sary to use the program effectively. T h r student muat furnish n mlculntor since the program does n8,t pprform arithmetic. Once one of the three programs is selected, the user can elect simple instructions on how to solve the problem or go straight to a problem. If the answer is correct, including the correct use of significant figures, the user is given the choice of selecting another problem or returning to the table of contents. If the answer is incorrect the user has the option of entering a new answer, a review of steps to solve the prohlem, or a tutorial exercise. All prompts are unambiguous and reouire the rememberine of onlv four commands An audlhle mtput, when a n meurrert rnput such a* nlphabrtrc key for numeric or space bar for return was used, was ~~
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Summary Ratlngs:
. ~.. ~
A206
Journal
of Chemlcal Education
Ease of Use Subject mner Content Pedagogic Value Student Reaction
Excellent Good Gad
Excellem
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