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:
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Ease of Use Subject mner Content Pedagogic Value Student Reaction
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helpful hut could he suppressed by the instructor. All computer operatians are rapid so that there is not time for the user to hecome anxious about whether the correct commands were used. The ESCAPE command will return the user to the table of contents allowing an easy exit from the problem. When the reviewer purposely tried wrong inputs he was unable to become stranded although two successive ESCAPE commands returned the user to the table of contents and lost the original problem. The program cannot be listed or modified. The subject matter is presented in a clear and exact manner that will be adaptable for most courses and effective with most texthooks since the use of terms is correct and unambiguous. The user has the option of starting with easy equations and advancing to hard examples. After solving four equations the user is returned to the table of contents. The equations are taken from a pool of 20 easy equations or 25 hard equations including challenging and unusual examples. If an error is repeatedly made, no correct answer is given hut a four-step review is offered. Although some equations involve oxidation-reduction, all tutorial explanations are based on an "inspection method." No distinction is drawn between metathesis reactions and oxidation-reduction reactions. The stoichiometric problems, both simple and limiting reactants, require the balancing of a simple equation before answering the question. This feature, as well as moderately complicated formula units and mole ratios, help to make these problems challenging. The use of dimensional analysis in the tutorial and sigrifieant figures in reported answers are two impartant features that make the program an educationally sound drill. One limitation of the short program is that only mass relationships are included without the option of solution stoiehiometry, gas law stoichiometry, or mole-mass relationships. However, this limitation does not detract from the quality or the stated objectives of the program. The approach is a truly interactive CAI providing drill and practices. The programs are among the best this reviewer has seen in effectively involving the user in learning the fundamentals of stoiehiometrie calculations. The strengths of these programs are the tutorials which divide the problem into step-by-step questions, correcting any mistakes and reinforcing the user's correct answers. For example, when errors are made in halancing eqv-+ions, the tutorial section asks the user ; i m many atoms of each element are present on each side of the equation and generates a table to assist in the inspection method. Common student errors, such as misinterpretation of the number of atoms in a compound eontainingpolyatamic ions with higher order subscripts are quickly identified. Likewise, in the stoichiometry problems, errors in interpretation and computetion are quickly identified. I t should he effective with those students who have difficulty with the problem-solving logic of multi-step problems. One common criticism of CAI is that the programmed instructions emphasize one method of solving problems and thus d o not encourage original approaches to solutions. Once the student has worked through the tutorial several times he or she may learn a "method" of solving problems with similar question format and yet not have a sound
understanding of the concepts. This criticism is valid for these programs sinee all of the stoichiometry problems in each pool have identical format and the questions vary only in giving masses of products or reactants. However, these programs would be very effective as a drill exercise shortly after being introduced to the general topic in lecture. The program was used on a voluntary hasis by students in Introduction to Chemistry and General Chemistry. Some students had never used CAI or logged onto a computer. In all eases the students were ahle to run the program without difficulty and without further assistance from the instructor. The interactive feature of the programs, the immediate checking of answers and the stepwise instruction in the tutorial were the features most often praised by the students. They felt that after a two-hour drill they were confident of being able to solve similar problems. Stoichiometric problems took from 45 minutes without using the tutorial. For mast, the tutorial section was used for only a few problems after which they felt confident in solving similar problems. Typical eomments were: "Homework is boring while the useof thr rompuwr w m fun and e n r ~ r u r a ~ e d me to t r y additional prohlemp." "I recewed more helpful practice in a shorter period of time than doing homework problems." "It was easy to work on my own." Most usen felt that instructions for each program went too slowly, although the elapsed time was between two and four minutes. Some felt that one solved example in the instructions would have helped but found that if the first answer was incorrect, the tutorial section sewed the same purpose. This reviewer was impressed with the ease of use by inexperienced computer users and the help realized by students who have difficulty understanding textbook explanations of multi-step computations and those who make careless or interpretive errors. One publisher of an introductory chemistry textbook has packaged the tutorial disk for a $5.00 additional charge. The program effectively accomplishes the stated objectives in teaching and drilling the student on three aspects of chemistry that often are difficult topics for beginning students. This reviewer was imoressed hv the intcractivr format, the ahsence of errom. and thr artmctivr enae of use by heginnera. I t is recommended as a good addition to a department's software library. Stanley R. Watkins ~
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Review I1
"The Chemistry Tutor," a software paekage that is designed to help students master the essential skills of equation balancing, stoiehiometrie and Limiting reagents caleulations, is a drill-type program for students in high school or introductory college chem-
istry courses. Its purpose is to help students learn the skills mentioned by presenting each of the three areas in a simple questionand-answer form. The program is basically a drill practice session, but through the use of tutorials that break the problem into a series of steps, i t becomes a teaching instrument also. This unit requires no knowledge of computers, but it does require some knowledge of chemical elements and compounds, and although the package has no higher levels of challenge for the advanced student, it is a good stepping stone to higher Levels of chemical problems. The documentation provided with "The Chemistry Tutor" is adequate for an understanding of the program. There is a short descriptionof the three sections and an even shorter question-and-answer part. The description might be widened to include a step-by-step review of the programs, and a list of the different computer keys and what functions they perform could be added to the second part. The starting instructions are found in the appendix at the end of the booklet and would he more useful at the beginning of the inatructions. The overall operation of the program is agreeable. Almost no computer knowledge rs needed to use it, and there are many assists for confused students. The user is informed when slow operations are taking place: the prompts are ample and mostly consistent; there is always a way out of the phase the student is in if he gets lost. There are two sound outputs used in the program: a huzzine noise to indicate that an error has heen made, and a rhckmg nmse 10 indicate that a pressed key has hem accepted R ~ t h wundscdn hc supprmsed hy the teacher. KO special equipmentis required, nor is itneeded to use the package effectively. A calculator and a table of atomic weights are necessary to complete the sections an Simple Stoichiometry and Limiting Reagents. The input handling of this package is typical for tutorial software. There are no keys that the student can press that will eradicate and display entirely. If the student enters any input that is not in the format applicable in that phase of the program, the buzzing noise sounds and the student may try again. The number answers are cheeked for significant figures, and althoughan answer with the incorrect number of significant figures is not rejected, an explanatory note is provided as to what the answer should be. The flexibility of use of "The Chemistry Tutor" is wide: it can he used hy various curricula and institutions, as it contains basic principles found in any introductory chemistry course. Its flexibility according to complexity is somewhat restricted; however, there are no advanced levels beyond "hard problems" (such as "challenge prohlems" or the like), but given the small price of the package, one would not expect much complexity. The program can be modified by the instructor on a few points such as sound output and character set selection (bold or normal), but it cannot he modified to fit certain levels or situations. The subject matter in the unit is chemically accurate and complete, except for a lack of distinction between mass and weight
Volume 63
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Number 8
August 1986
A207
which the chemistry teacher tries to describe to hisstudentsas unequal, are used as synonyms in this discussion. Overall, "The Chemistry Tutor" is a goad tutorial program that reviews three major areas in which chemistry students usually encounter problems. in one part of the program. The steps explained in the discussions are well worded and clarifying. By helping the student if the wrong answer is consistently entered, the computer accommodates lower Levels of ability as well as higher levels. Also, the format of the problems, the input, and the output remain constant throughout the three programs; this helps the student to make a smooth transition from onelevel to the next. The pedagogy of "The Chemistry Tutor" is sound, hut not altogether innovative. I t employs problem solving, drill and practice, and tutorial computer-assisted instruction to acheive its goals, providing a "worksheet7' on which the student may work without having to do written work. However, there are a few things that could he added to this program to make it more interesting. For example, samples of worked problems for the students to study could be very helpful in understanding the notation of the program. Student reaction to this program has been favorable. Ten students ranaina from eolIeze fre.
