This action takes the user to a submenu from which the other drill mode is accessable or from which the student can access mode 11, the search mode. While in the drill mode, the program keeps track of all student responses. When the student finally leaves this mode, the program prints a summary of results. The four categories listed are: problems correct on the first try, problemicorrect on the second try, problems with no second try, and problems missed on both tries. The program also generates a coded number a t the end of the drill mode. This number, when decoded by the professor,indicates how many total problems the student has tried in a session with the program. With mode I1 the student can search to total data set for reactions involving specific reactant functional groups, product functional groups, or reagents. For example, the btudrnt can nearrh f&nlfreactionein whirh an nlrohol is the stsrtinr material or do a more limited search for reactions in which an alcohol is the reactant but only aldehydesfketones areproducts. As another example, the student can search for any reactions using dichromate as a reagent. Mode I1 is also menu controlled and needs no external prompts or directions. However, i t does require the list of reagents for a reagent search. When finished with the search mode, the student can switch back to the drill mode or quit. Some of the advantages of Organic Reaction Chemistry over previous programs are that all the organic reactions are on one disk, the student can work on supplying both product structure and reagents, the program is graphically oriented, the search mode allows linking reactions across chapter boundaries, the summary a t the end of the drill provides quantitative feedback, and, finally, with mode I-B the student must actually construct the product molecule and just look a t a flash card and mentally say, "Yes, I know the structure of that product." Organic Reaction Chemistry is written in Applesoft Basic and occupies 18K of memory. An additional 1K of memory is occupied by the binary tables of reactants and reagents. The program runs on an Apple IIe or 11+ with lower-case chip. There are 150+ reactions in the data set. The program is currently available by sending a blank disk in a prepaid envelope and $4.00 to the author. The program has been submitted to Project SERAPHIM and may be available through them in the future. Acknowledgment . I would like to thank the National Science Foundation (the RISE program, grant SED 8020159) for the funds that were used to pirchas; the Apple computer system on which the program was written and studept-testad.
Comput Program tor Allocation ofirganic &litatin Analysis Unknowns
the students may use IR and NMR and have access to spectral libraries, they are required to perform chemical classification tests and nreDare two derivatives to confirm each idcntification. ~ h ; unknowns . are l i m i t d to those found in the tablesofthe CRCHondbookforIdrntificotionof. Ormnic Compounds, 3rd edition. The selection of appropriate unknowns for relatively laree numbers of s t u d e n & ~ t y ~ i c a l50-70 ly per semester) had hecome a somewhat tedious task, particularly in terms of making certain the class received a-random group of unknowns rather than the same combinations of compounds year after year. To this end we have developed a computer program written in IBM BASICA to generate a random group of four unknowns for each student. This program has been successfully used for the last four semesters a t Illinois State University. The program consists of a file of possible compounds belonging to the six classes mentioned previouslv. in . Tvpicallv .. less-than one-half hour the programkill generate a group of four compounds (two singles and a mixture) for each student. These must fulfill the following specifications: (1) no student will receive two compounds having the same functional group (aldehydes and ketones are considered to have the same functional group); (2) each student will receive a t least one solid and one liquid; and (3) the mixture will be separable by acid-base extraction techniques. The total nrozram consists of five individual seements . that are automatically loaded into the computer and selected from a simple menu (INTRO). The SETUP selection creates the file of unknown compounds, and allows for changes in this file. ALLOCAT chooses two single "unknow&" and an "unknown mixture" containing t a o compounds per student. The PRINTOUT selection is also menu-driven and produces a variety of printouts. The complete compound file and a listing of the compounds by a selected functional group can he &wed on the monitor with the selection SCREEN. The fifth program. DOCV,contains general information about the entif.e program and alisting of the variables used in the other four programs. The "unknowns" are randomlv selected from a source file that currently contains approximately 200 compounds classified bv the six functional zrouns " . mentioned nreviouslv. Since many compounds have more than one functional group, compounds containing halo, alkoxy, cyano, nitro, and vinyl substituents are also in the file. Aromatic, aliphatic, cvclic. and heterocvclic structures appear as well. The first sk~ectionof the SETUP program asksthe user ten questions about each compound being placed in the "unknown" file. The second selection allowsadditions, corrections and deletions; consequently the compound file can readily be changed to reflect the availability and needs of a particular school. Error checks are present t o catch many predictable entry errurs.After new compounds have beenadded,a printout of the new material ran be obtained. Figure 5 shows the information entered for a typical compound.
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Ann L. Pontius and Michael E. Kurr Illinois State University Normal. IL 61761
At Illinois State University organic chemistry students perform specific experiments stressing a variety of important synthetic reactions and techniques for the first half of the semester, and then devote the last half (which entails about 14 3-hour lab periods) to organic qualitative analysis. During this time each student is given two single "unknowns" and a mixture of two components to characterize and identify. We have chosen to limit the unknowns to six classes of com~ounds(aldehvdes. , ketones. alcohols..nhenols. carboxylic acids, and m i n e s ) , which are quite readily characterized by both chemical and spectral methods. Though
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Figure 6. Instructor listing of mixture compound data. Volume 64 Number 3 March 1987
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The ALLOCAT program selects two unknowns per student utilizing the entire master file. Each compound has a chance of being allocated only once. Anumbered and labeled list of the selected com~oundsis printed for use by the storeroom personnel. A; additional numbered listing of compound information is printed for the lab instructor. This includes the melting or boiling point, formula, functional group present, type of compound, and any nomenclature synonyms. Figure 6 shows an example. The number of compounds chosen hy type and functional group is also printed. The selection process creates a sequential access file "Second.has" that is needed in the mixture allocation process. The ALLOCAT program selects compounds for "unknown mixtures" taking into account the two previously allocated unknowns. Because separation is accomplished by aqueous extraction, only those compounds that are water insoluble and ether soluble are eligible for the mixtures. Approximately 60% of the compounds in the file met this criteria. Each of the eligible compounds may he used twice during the mixture selection. Another parameter for mixture distribution allows only the combinations of strong acids, weak acids, bases with neutral compounds, and bases with weak acids. Because of incomoatihilitv nrohlems amines and aldehydes are not combinedin an '&known mixture". A counter included in this section allows the program 750 tries to find a suitable mixture match. If no match is possible, this information is recorded for that mixture numher. This menu selection also produces a storeroom listing and an information listing for the instructor. At the berinning of this selection, the requests a name for the file that will store the names of the four compounds given to student #1, #2, etc. Additional copies of all listings can he obtained through the PRINTOUT program. The sequential access file created by allocation of the mixtures is called 'Mixlist.has". One complete cycle of the program with approximately 200 compounds in the "Unknown" file produces four compounds each for approximately 75 students. Requesting more matches than this creates problems in finding suitable compounds to make the "unknown mixtures". The program can he run several times to produce alarge numher of comhinations. Options from PRINTOUT include hard copies of the entire"unknown7' file with all information, a &ing of only one functional group, a copy of the entire file by functional group or type, and a listing of the compounds availahle for the mixture allocation. Additional copies of storeroom listings and instructor information plus compound listing of any previous sessions run are also availahle through PRINTOUT. A printed copy of the compound file, "Unknown", is necessary to make corrections t o any of the previously entered data. The total numher of compounds by type and functional group is included in the master listing, along with any dropped and unusable compounds. The program was designed to run on IBM-PC's or compatibles usiue PC or MS-DOS. one disk drive. and a orinter. The SETUP, ALLOCAT and PRINTOUT piogramdoccupy 22.000 to 26.000 hvtes of disk space: DOCU 14.000 hvtes: SCREEN 5,800 bytes, and the ~ N T R Omenu 1;200 bytes: The numher of bvtes used hv the secluential access files created during program execu$on depends on the numher of student compounds requested. One file (First.has) created as the program runs is eventually erased, and files "Second.has" and "Mixlist.has" remain on the disk until that particular selection is run again. The length of the "Unknown" file containing the compound information depends on the number of compounds entered. For approximately 200 compounds the file occupies approximately 26,000 bytes. The authors wish to thank Stephen Gates, Department of Chemistry, Illinois State University, for his programming assistance.
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Journal of Chemical Education
Color Images of Molecules John J. Farrell Franklin and Marshall College Lancaster, PA 17604
After reading Viewing Molecules with the Macintosh by Earl J. Kirkland (11). I was inspired to write a similar program for the IBM PC in color. COLOR3D.BAS is a BASICA -aroeram for anv IBM PC with a color monitor. The orwram draws three-dimensional images of complex molecules. The user must s u o ~ l va file that contains the followine information for each atom: anumher corresponding to t h e h o r to be used, the x,v,z coordinates (in anastroms), and the radius (in angstromsj. The molecule is displayed with hidden surfaces hidden. Each type of atom is dis~lavedin its designated color or color $&tern (carbon in bluk, hydrogen inwhite, boron in magenta-and-white check, and so on). The molecule can be rotated about two axes (the azimuthal and polar axes on the screen). The user can supply a viewing distance (from the molecule). I t takes the computer 20-40 seconds to draw a molecule. The program can he used in chemistry courses to depict conformation of molecules, effective and ineffective collisions, elements of group theory, and unit cells of crystals. A more detailed description of the program and some color pictures of the images generated can he found elsewhere (12). A 5Y-in. floppy disk that contains COLOR3D.BAS, seven files for various molecules, a listing of the promam, and a complete description of the program and howto use it, is availahle from the author. Send a check for $20, payable to the author, to cover the cost of materials, postage (domestic), and handling. Also, COLOR3D.BAS is availahle for downloading from BYTEnet listings a t (617) 861-9764. You will need an IBM PC or PC compatible with BASICA and an RGB monitor to run the program.
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A Cammodare ~icrocomputer/~ettler 440
galanee Interface &in
Harvey F. Blanck Peay State University Clarksville, TN 37044
While some digital laboratory devices are specifically designed to interface easily to computers by providing digital information a t a socket or edge connector, many do not. However, the information sent to the LED display unit may in some cases he easily intercepted and sent to a microcomputer. As an example, I will describe an interface used to obtain data from a Mettler 440 electronic toploading halance. The digits are displayed sequentially and repetitively a t a high enough rate that they appear t o he on continuously. This refresh cycle is controlled by a microprocessor output with one dieit select line for each of the six ~ossibledigits and one line for each of the seven segments forming t h e digits. In the interface to he described the microcomputer sorts out the data after acquisition. This method avoids latches and results in a dramatic reduction in the amount of hardware and time needed to construct the interface. In this example i t is possible to reduce the information necessary per reading to eight lines. The data from the sixdigit select lines may be reduced to three lines using a 74C10 chin. .. which is a tri-three inout NAND eate (Fie. . - 7). . Although digits may require up to seven segments for visual disolav. . " . onlv five a m r o ~ r i a t e l vselected segments need he monitored to distinguish between each of
