Principles of Stoichiometry (Gold, Marvin) - Journal of Chemical

Keywords (Audience):. High School / Introductory Chemistry ... Journal of Chemical Education. Darrow. 1989 66 (1), p A43. Abstract: This program is di...
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that the software will generate in a given topic area. The computer then randomly selects questions from over 600 compounds or 50 equations. If a correct answer is entered, the student is immediatelv told this. If the response is incorrect, asecond chance is provided. A hint may even he given about why the first response was wrong. A percentage score is presented at the end of the session. Thus, I found the pedgogical approaches of hoth disks to be very effective. This software package also comes with a well documented courseware guide. The user has a detailed description of the followine: hardware reouirements.. oneratine" instructions, potential input problems, recommendations for product use, and goals and aims for each module Alma pretest and posttest are available for the instructor. Since the disks are copy protected, they may not be duplicated. However, a backup set of disks is supplied, and arrangements can he made with the company for more copies. In summarv.. all information needed to use the nackaee successfullv is nrovided ( h e r a l l y , there programs are very easy to use. No prwr wmputer erperlence 8s needed by a first time user. All important features are found on the screen. Any other problems may be resolved by consulting the manual or by calling the company. Several improper inputs, such as hitting the reset key or control key while pressing other keys, may disrupt the programentirely. The only way out of this situation appears to he to reboot the disk. Also one aspect of the input process seemed awkward a t first. The ESC key must be pressed before a capital letter is entered for a chemical symbol or formula. However, if the ESC key is used hefare a ~arenthesis or subscript, the screen will appear normal to the user, but the computer will not interpret the response properly. Thus, a correct response may be marked as being wrong. Lastly, I felt that the needed input was inflexible occasionally. For example, a positive three for e charge must be entered as 3s:3 is not accepted. Likewise the formula for acetate muor be entered as CHQCOOand not C2H302. This software was tested with a group of about 30 elementary chemistry students over a three-quarter period. This course is designed for college students who have never had high school chemistry. AU participants were students who had volunteered their time to help evaluate this software package. Generally, these students reported that they enjoyed using these programs and said that the software helped them to learn the material. Many commented that these computer programs were more interesting than their textbook! On the average, each module took about 15-20 minutes to complete. Most of these above average students drd well when evaluated over these topics. Their b~ggesrcompla~ntwas the use of the o n also cumESC kev tor c a ~ ~ t a l ~ z a t iSome mented-that they wished that the program would give acids and nonmetal-nonmetal compounds far examples. In summary, I will continue to use this package for our beginning students, because

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it helps me to teach them these important topics. However, I feel that the content of the disks could he expanded to make the package even more useful. Timothy A. Kling Lakeland Carnmunlty College Mentor, OH 44060

Prlnclples of Stolchiometry Marvin Gold. COMPress. P.O. Box 102. Wentworth, NH 03282 Hardware: Apple II famlly Components: 1 disk, Teacher's Manual Level and Subject: High school or college general chemistry Cost $40 ($100 for a LabPack of 5 copies) Summary Ratlngs:

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ca1egory Easa of Use: Sublect Matter Content: Pedagogic Value: Student Reaction:

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The program is contained an a single double-sided disk and is most appropriate for students enrolled in a second year of high school chemistry or a first-year college chemistry course. I t is primarily a tutorial supported by nonrandom generated prohlems which require user input. The program is copy protected and cannot he adapted to meet local needs. The software is accompanied by a 12-page teacher's manual that adeouatelv describes the programs and establisies tde objective for each unit of study. A student's manual is not nroviderl ~~- .. . -. -. The program is menu driven. Instructions throughout the program are unambiguous, easy to follow, and require a minimum of computer competency. Program structure is semi-rigid but does allow the user to return to the main menu at appropriate times. Withineach section a previous page of information cannot he reviewed without returning to the main menu and restarting the section. This structural arrangement presented some difficulty to the students, who frequently wanted to review a previous page of information. The program's weU-written introduction defines stoichiometry, lists the program objectives, describes how the program is designed to accomplish the author's goal, defines the protocol for user-computer interaction, outlines the program, and provides practice entering values from the keyboard. Error trapping of keyboard input is generally effective. However, the DrOEram asks the user to type in +25 and late; -25 and accepts values like +25.9 and -25.9; whereas, it rejects 25, in place of +25. Similar mishandling of user input also occurs in the last unit of study. The program is partitioned into two analogous parts, each with six study and two testingunits. Part 1, on side one of the disk, ~

employs a sandwich analogy, and part 2, on side two of the disk, uses ammonia produetion to present the principles of stochiometry. The six units of study are balanced equations, limiting reactant, value table, ork (mole) concept, arks and slices (moles and molecules), and orks and grams (moles and ersms). " ~ a ; h study unit includes a short tutorial followed by several problems. The problems are relatively easy but do require pencil and paper. Correct answers produce s variety of brief approbations whereas incorrect answers produce conteat-sensitive responses. Students operating at the main level are usually given two opportunities to answer a question correctly. The first incorrect response results in a suggestion of how-to-proceed and the second usually in remediation. Two chemistry teachers, three students who had completed one year of regent's chemistry and were currently in regent's physics, as well as two students currently in regent's chemistry reviewed the programs on the disk. The analoe" on side 1 - involves . eonstmrting a sandwich from 2slicesof bread, 3slices of ham, and 1dice of cheese. Theequatiun is 2H + 3H + C = S. The ch~mistryequivalent is the formation of ammonia from nitrogen and hydrogen according to the equation Nt +3H2=2NH3. The unit on balanced equations considers the usual quantitative relationships hetween the coefficients of a balanced equation. The user is not required to balance any equations. The tutorial section is well-written. However, in part two, the nitrogen molecule is represented as N-N rather than N=N. Student users were not aware of this misrepresentation. Remediation in this unit, as in other sections, ignores units of measurement. Equations often take the form, 96 X 113 = 32. Dimensional analysis would enhance the effectiveness of this program. The balanced equation study unit on side two was unfriendly. Two incorrect responses to the first question terminated this unit of study. The user is required to return to side one or reboot the disk. A better solution would he to hranch the user automatically to the start of the study unit or allow the user to continue. The limiting reactant study unit included a well-written rutorial, s dictionary page with the definitions of limiting end exress reactant, and a nondancing "dancing analogy." Frequent access to the dictionary page and the dancinganalogy were the highlights of this unit. Suhject matter presentation was standard. Four errors were encountered. First, the user was asked to enter B, S, or C where the author clearly meant B, H or C; second, two incorrect responses to Question Two resulted in incomplete clearing of the screen and new text overlaying old; third, at one place "n" and "h" used to represent nitrogen and hydrogen; and fourth, a misprint occurred in a remediation message. The value table unit presents a standard bookkeeping method for tracking the reactants consumed in a reaction. Terms used in the unit were defined and a protocol for entering values re-established. The tutorial section was very good. Continuity with the previous unit was established hy using values determined previously in the example ~

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value table. The presentation was clear and exact. However, two incorrect responses to a question on side two solicited the correct answer and the phrase "we're making good progress". The students found this unit satisfactory. The ark (mole) unit joins together the information from the previous study units. An ork (nonchemical mole equivalent) is 2M) slices of a reactant (bread, cheese or ham). The presentation is accurate and reflects a classroom lesson. Comments from the student users varied from "one more thing to know (ork)," to "there should he more mole problems". In the tutorial section, one mole each of nitrogen, hydrogen and ammonia is represented by three hoxes of different heights. No relationship between the relative masses of the molecules and the respective heights of the boxes can he established because mass has not yet been introduced. Such a representation may he a little premature. However, the student users did not question this representation. The students found bath the sandwich analogy and the chemistry section of this study unit equally difficult. Program structure eontrihuted to their difficulty in that sequential wrong answers resulted in termination of the study unit. Additional remediation in this unit would have been helpful. The students should have been channeled to the beginning of the study unit rather than out of it. The final two study units, ork-slice (molemolecule) and ork-gram (mole-gram), represent a classical presentation of the subject matter with problems similar to those usually discussed in a classroom. The mole-molecule unit has a very good section on scientific notation which was most useful to the students. There was some mishandling of user input as noted a t the beginning of the review. The author reintroduced bores of different heights to represent one mole each of nitrogen, hydrogen, and ammonia in the mole-gram study unit. There was no discussion of the relationship between the heights of the hoxes and the respective molecular masses. According to the estimates of this reviewer, other things heing equal, the heights ofthe hydrogen and ammonia hoxes need to be reduced approximately 30 and 9 percent, respectively, relative to that of nitrogen, for proper representation. The last two sections of this tutorial enjoyed a favorable reaction from the student users. There are four self-test units, two for each part of the disk. Each self test covers three study units and consiste of three questions for each unit. There is no remediation. A short buzzer-type saund Indicates an incorrect response and a short happy sound praises a correct response. The questions adequately reflect the suhjectmatter in both depthand difficulty. The students need to understand the subject matter of the tutorial to answer the questions correctly. The overall presentation of the information is good. Definitions and explanations are available when necessary. The progression of the presentation is logical and weUidentified. The problems are relevant at the point of instruction. Students who completed their first year of chemistry found the package relatively

esay. They would have preferred that the author spend more time on chemical storchiometry and to present a greater variety of prohlems. Students taking their first course in chemistry experienced same difficulties with the oackaee. The inahilitv to move within a &en .. siudv unit and tb look a t a previous page of information, the automatic branching out of the study unit, and the need for more remediation were their primary difficulties. Discussions with the above student users seem to indicate that the package is most suitable for students enrolled in a second course in high school chemistry or those in first-year college chemistry.

Frank Montagnino Cardinal Spellman High S c b l 1991 Needham Avenue Bronx. NY 10466

use, similar to those found in most romplete laboratory manuals, would be a useful addition to the package. The program is divided into fourmodules. A well done graphic illustration of an experimental set up illustrates the "experiment" being done. The illustrations are especially nice with a color monitor, but monochrome is certainly acceptable. In the three modules on the solubility behavior of solids in liquids the illustrstion is of a beaker containing solvent to which small portions of solid are added. When the saturation limit is reached solid material appears on the bottom of the container, and the data display tells the amount of solid which has dissolved, and the total amount which has been added. The space bar "pushes" portions of solid from a ledge above the container into the container and the mixing of the solid with the solution is accompanied hy s short saund. The fourth module, illustrating the mixing of two liquids, is illustrated by two spigots aver aeontainer. When the "experiment" is started the spigots turn and liquids flow into the container. The spigots turn off and time is allowed to oass to determine if the liauids mix or not. Buth illustratima are good, and students responded positively to them. What they are depicting is cleat, with m e exception noted below. In the first module portions of a known solid are added to 100 g of water after a temperature has been chosen (in 10 degree intervals from 10 "C to 70 'C). I kept expecting the up and down arrow keys to adjust the temperature, but the left and right arrow keys are the correct ones. After four points have been recorded, the program plots the data on the screen and displays the known soluhility curve on the same plot. A short quiz follows to test student understanding of what has just been done. One question asks the student to decide if the solubility decreases, remains the same, increases slightly, or increases substantially as temperature increases. There are no criteria given to decide the difference between in-. creases slightly and increases substantially. I t is frustrating to know that the soluhility increases with an increase in temperature and also to he told that your answer is incorrect because the program has a slightly different definition from that which you have learned. A potentially confusing question on the quiz asks for the solubility of the compound at a particular temperature. The student is shown the data that has been recorded, even if it is incorrect, hut the only answer that is accepted as correct is the one that the student should have recorded. The program includes an option to print the data and olot. which is useful for notebook records. Yhe'printed plot shows the recorded data and nut the known solubility rurve, whirh can be misleading if mistakes have b e ~ n made in recording the data. In the second module, a computer chosen unknown is the suhject of a soluhility determination as in the first module. After the data are collected and the plot is drawn, the student is asked to ideutifv the unknown hv comparing its data with that in the distributed solubility table or its solubility curve uith the distributed solubility curves. The

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Solublllty Richard Halloren. Educational Materials 8 Equipment 60..old Mill Plain Road. P.O. Box 2805, Danbury. CT 06813

Hardware: Apple II famlly Components 1 dlsk and 1 backup, Study Guide Level and Sublect: High school and introductory c o l l e g e chemistry

cost: $44 Summary RatlwS:

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c*esory Ease01 Uw: SubjeclMatta content: Pedagogic

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Student Reactlon

Revlew Solubility is intended to supplement Ishoratory experience in solubility determination. I t would he useful in high school and introductory college chemistry courses. I t will he most useful if students have had direct laboratory experience, hut it could also he used followine ..demonstrations hv the instrurtor if time or farrlitiesare limited. The provam rs an a single ropy.pnmcted dirk with s harkup. A Study Guide cuntaining a brief overview, hackpouud information, description of the procedure for each of the simulated experiments, and a set of worksheets to he copied and distributed to students accompanies the disk. Permissioh is given to copy only the worksheets and the soluhility tables and curves. Teachers will find that they either must he readily available for instruction or that they must write out their own description of experimental procedure. A more detailed statement of theory and procedure intended for student ~~

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Volume 66

(Continued on page A44)

Number 1 January 1969

A43