In addition it is not difficult to output numerical results in such a way that they can he compared directly with analytical solutions. Programs employing this numerical-graphical approach to quantum theory have been written for several one-dimensional examples that have recently appeared in THIS JOIIRNAL: the particle in the chemical box (KEMBOX) ( 4 ) ; the particle in the one-dimensional champagne bottle (BOTTLE) ( 5 ) : the perturhed-particle-in-a-box model for the a-electrons of octatetraene (PIELEC) (fi);the one-dimensional hydrogen atom (HATOM) ( 7 ) ;and an SCF treatment of a one-dimensional model of the helium atom (HESCF) (7). Far example, Sims and Ewing (fi), using a 10-term linear variation function. ohtained an enerav .. of 31.573 cm-I for the first a-electnm transitinin octatetraene assuming a "perturhed particle in the box" model for the a-electrons. Using ..
.
cm-' was obtained. All five programs were written in LEVEL I1 BASIC for the TKS-80 Microcomputer. HESCF is by far the largest program. It consists of 70 multistatement lines of BASIC code with 22 remarks and occupies 3.8 Kbytes of memory. PIELEC is representative of the other programs. It consists of 40 multistatement lines of code. contains 18 remarks and reauires 1.8 Khytes of memory. ~ i s t i n g sof the programs plus associated documentatim mav be ohtained. fiee of charge. from the author a t the address given ahave.
the search program ran he used by the student. This program asks the user for the numher of spertral peaks observed. Following input ofthis informat,ion,the user is asked to estimate the wavelength at each peak location. After t,he student has entered the last of this data, the program prints out a list of t,he nrmpoonds in its tahles that match the first wavelength, then a list for the second wavelength entered, and so on. If the tahles do not contain any compounds that match the input wavelength, a message to this effect is printed. Finally, the program prints a list of all compounds in its tables that match all the input wavelengths. If there are none, then a message stating this is printed. ~ h package d of five programs is interactive ANSI-standard BASIC, with a total of 262 statements and 116 comments. Students run m l y the search program (78 statements, 37 comments), and this is done on a terminal. Execution of the search program requires 2K 16-bit words on a DEC PDP 1110'3. The oackaee reauires 38 blocks on DEC RX02 flovuv disk, and tables &r 106 compounds require 16 blocks. tahles are not included with the nackaee.) 1)ocumentation includes listing and separate instructions for using the package. Users of each procram are riven instructions and DromDts
he
..
dames C. Howald, Department of Chemistrv, Huntington College, Huntington, Indiana 46750.
Computer Drill in Thermodynamics John M. Chamberlin Western Kentucky University Bowling Green. KY 42101
Interpretation of an Infrared Spectrum on a Minicomputer James C. Howald and Francls L. Jones Departments of Chemistry and Mathematics Huntington College Huntington. IN 46750 A tvoical course in organic chemistrv usuallv includes an .. interpretation of an infrared spectrum. This can he quite time consuming because the student is required to search lengthy correlation tahles tcr identify the structural component resnonsible for a given wavelength. Although it is beneficial for the student to'hecome famifiar with co;relation tahles and other literature, it would he advantageous if the search process could be done more efficiently. A literature survey reveals that several computer search programs have been written that would aid the student in this and other types of exercises in organic chemistry (8-11). A program would also have the virtue of giving the student an introduction to the concept of using a computer in chemistry. The direction taken a t Huntington College was t~ have the student use both a computer search to make preliminary identification and then to use a more traditional literature search to refine the soectral interpretation. To this end. a oackaee of BASIC oroerams and data files were developed f i r a D I k PDP 1 1 / 0 i c o & 1 t e r .The package consists of a searching program and four service programs that create and edit the twu tahles. The tables are stored as virtual arrays on floppy disks, which permits the use of much larger tahles than could be accommodated hy the main storage of the l l / O R . The first table contains rows of three numbers: a peak's lower houndary, its upper boundary, and a code integer that is used to link the uair of boundarv numhers with the name of the compound. The latter is stored in the second table in a row whose position numher equals the code integer. The instructor initially opens and fills each tahle using the respective service programs. After the tables have heen created and (if need be) edited, ~
554
Journal of Chemical Education
~
Because of the very broad utility of thermodynamics in chemistry and in other sciences and because of the profundity of the discipline, it is important that students in physical chemistry hecume well grounded in the fundamental concepts and calculations of thermodvnamics. One of the crucial initial steps is the calculation of virions thermodynamic quantities for ideal gases under systematically varied conditions. In order to facilitate this goal, seven different computer programs, THERMI through THERMI, have been devised that present students with a set of initial and final conditions for a particular ideal gas and then ask them to calculate the heat and work and the changes in internal energy, enthalpy, entropy of the system, entropy of the universe, Helmholtz free energy, and Gihhs free energy for the process. In addition to such standard processes as reversible isothermal expansion/compression and reversible adiabatic expansion/compression, the seven programs include various irreversible processes. The calculation of free energy changes for non-isothermal processes, which invdves absolute entropies and which is avoided hv most texts. becomes a routine procedure for students through these drills. Also, the fundamental significance of the total entropy change of system and surroundings is emphasized by the student's having to calculate it for each process and bv the proeram's making a statement as to its ;elation to the;eversibilky and the spintaneity of the aiven process. Since the First Law is always
or else all eight. Data for each trial, such as the temperature, pressure, volume, and mass of the gas, are all generated randomly. One of ten common gases is also randomly selected. Average heat capacities and absolute entropies, required fur some calculations, are provided by the program. A f2% error in the student's response is accepted hy the computer. Although a
