Distillation and the Macintosh: PT Nomograph, An "ln-Lab" Utility R. Slmon and T. Seneca13
University of Colorado Boulder, CO 80309 With the advent of such programs as Wisconsin's WIMP, ChemIntosh, and Chemdraw, access t o convenient, easy drawing of chemical structures has now become indispensable to the organic chemist. We wish to report the development of a program (desk accessory for the Macintosh) that moves the microcomputer directly into the laboratory: P T Nomograph (v.2.0). General Features of PT Nomograph (v.2.0)
Figure 5. Percent boundary surfaces for hydrogenatom i s and 2s wbite.1~.The surfaces enclose 10%. 20%. . . . .90% of the electron density. Planar cross seclions are shown. The marks the nucleus. The solid line in the upper right b n d corner gives Me scale, and represmts one Bohr radius (53 pm). 1s surfaces -, 29 surfaces 2s node..
+
--
-.
.....
1. The 90% boundary surface for the 1s orbital is contained wholly within the 10% boundary surface of the 2s orbital; the 90% boundary surface of the 2s orbital is contained within the 20% boundary surface of the 3s orbital. Thus, the three orbitals concentrate the electron in very different regions of space, as the shell model of course imnlies. 2. The distances between successive surfaces (i.e., the surface soacines) in the 2s orbital are about 3 times as laree as thosein the-1s orbital, while the spacings in the 3s orbit2 are rouehly 5 times as laree. Further, the spacines follow the s&e pattern in each orbital, first decreasingand then increasing. It is enlightening to discuss these patterns with reference to plots of the radial distribution functions. 3. The 2s node occurs within the 2s 10%boundary surface. The inner 3s node lies verv close to the 2s node and is within the1090 boundary surfaces of both the 2s and the 3s orbitals. The outer 3s node is within the 20% boundarv surface of the 3s orbital. More than 80% of the electron density in the 3s orbital is beyond the second node. I t is very hard to get a feeling for these features from plots of the radial distribution functions alone. 4. Taking the 90% boundary surface to be a measure of atomic size implies that the radius of a hydrogen atom in an excited 2s state is almost 3l/2 times as-large as that of a ground state hydrogen atom, while the radius of a hydrogen atom in an excited 3s state is more than 7 times as large. The 90% 1s boundary surface radius is 141pm, compared to the hydrogen single bond covalent radius of 37.3 pm (18), the hydrogen van der Waals radius of 120 pm (la), and the hydrogen (H-) crystal ionic radius of 154 pm (18). Comment
This assignment has been very successful in generating excitement amone the students and even effort beyond what is strictly required. I credit much of their interestto the fact that the students create the percent boundary surfaces themselves from start to finish-no theory from "outside the scope of the course", no distraction by fancy numerical methods, and no "canned" programs from out of the blue.
,
This Droeram duplicates the eeneric ~ressure-temoerature nomograph, fo&d in a variety of so&es, for the determination of the boiling point of a liauid under reduced pressure (19).No longe;is one requiredto use paper nomographs with mlers and pencils and "eyeing" it; no more "where did I put that Nomograph?" or "Dam, ripped the piece of paper its on.. .". Now this valuable tool for the brganic chemist is a fingertip's reach away. The accuracy of this version of the pressure-temperature nomograph is comparable t o that of the conventional nomograph; however, i t is easier to obtain more precise values. As before, this method should be used as a guideline for the
-0
P I homograph rnrn
Corrected to 760 rnm
Observed
mm)1 Observed Corrected
Pressure
Calculate ... About PT Nomograph ...
Figure 6. PT Nomograph using Method 1: a line is hand drawn with lhe mouse.
determination of the boiling point of a liquid under reduced pressure, not as an absolute measurement. A rough estimation of the obtained boiling point is i 5 "C. P T Nomograph can be used t o calculate either the boiling point a t atmospheric pressure for a compound, the boiling point a t reduced pressure for a compound or the reduced pressure as long as the other twovalues are known. This desk accessory may be used in two ways: Method 1:acompound which boils a t 100 OC a t 0.1 mm Hg can be calculated to boil a t 322 OC a t atmospheric pressur ?. Using this method, one clicks with the mouse on 100 ("C) on the Observed line. Holding the mouse button down, the cursor is dragged to the 0.1 mark on the Pressure line (in mm Hg). The windows a t the bottom of the screen print (Fig. 6) 410 Cody Dr..
Lakewood. CO 80226.
Volume 67
Number 6
June 1990
505
[EO
PT Nomograph
Observed
-
Corrected
to 760 m m
.C 400-
'C 700600.
300-
500. 100.
200.
300-
ZOO100-
Miscellaneous Information PT Nomograph (v.2.0) is a Lightspeed Pascal programmed desk accessory compatible with all versions of the Apple Macintosh ranging from the 128 K to the Mac 11, and with most systems. I t takes u p minimal space (15 K) and is availahle as share-ware. We do request that a disk be sent on which to conv the nroeram. An older version of P T Nomograph (versib;ll.O, kh$h only utilizes method 1, and 11K) is also available on the GEnie Mac Roundtable in library # 5 for desk accessories in file #9288 (posted by John Clark, Universitv of Colorado a t Denver and through "Info-Mac" on A R P A ~ ~ ~ ) . Literature Clted
100-
1. 0-
Observed Corrected
ChungPhillips, A,; Rosen, R. W. Computer J. 1975,18,342-343.
1. Chung-Phillips, A.; Rase", R. W. DYNAM. Project SERAPHIM, Madison, WI. 3. Amend, J. R.; Furstenau, R. P.: Tucker. K., submitted far publieatian in J. Chem.
Pressure
Calculate... 6. Brsydich, M. D. "The Periodic Table: The Adventure Beginn", USAF Academy, CO,
,an"
Fqne 7 Memod 2 for PT homograph two va uesare entered in the boxes a1 the mnom Cllcr~ngon C a m ate ' wnm the moure gwesthe mird value
7. Range. E. R. Compvlsra Chem. 1976.1.91. 8. Breneman, G. L. J. Chem. Educ. 1974.51.812. 9. AguirrcOde. F.J. Chem. Educ. 1987.M,957-958. 10. Caidinali,M.E.,Giomini.C.:Marrosu,G.,submittedforpublicationinJ.Ch~m.Educ. 11. Cromer, D. T. rl Chem. Edvc. 1968,45,626632. 12. Karplus. M.; Porter. R. N. Atoms and Mobeulas: An Introduction for Students of Phyaicoi Chemistry; BenjsminlCumminga: Reading, MA, 1970:pp 130-139. 13. Streitriesser, A , Jr.: Owens. P. H. Orbital and Eiactron Density Diogromr; Mannilla": New Yarh, 1973. 14. Gerho1d.G.A.; McMurchie, L.:Tye,T.Am. J. Phys. l972,40,986993. IL Kikuchi.O.;Suzuhi, K. J.Chem.Educ. l985.62.206209. 16. Lieh1.M. J. Cham.Educ. 1988.65.23-24 isoneaf the moat recent ofthese articles. See slro the literature cited in ref 15. 17. Oahlquisl. D.: Bjorck, A. Numancol Methods: PrenticcHsll: Englewaod Cliffs, NJ,
display the selected values. I n this case, the value for the boiling point a t 760 mm Hg pressure is read from the middle box. T h e same type of calculation can he performed using method 2: with the mouse, click in the Observed Temperature box and enter the desired temperature (100 "C; see Fig. 7). Then click in the Pressure box and enter the desired value in mm He. " In the remainine box. a value of 0.00 must be entered. By clicking on the field "calculate.. .",the third value IS automaticallv calculated and displaved. A line is also drawn on the main nomograph picture a;kmatically. There is a dialoe box that comes U D automaticallv if there is an error.
.-,-. ,a,"
18. Weest, R. C., Ed. CRC Handbook of Chemistry and Phyrira. 62nd ed.; CRC: Boea Raton, FL, 1981. 19. (a) Pavia, 0. L.: Lampman, G. M.; Kdz. G. S. Introduction t o Orgonic Lobomtory Terhnioues: A Contemporary Approorh, 2nd ed.: Saunders: New York. 1982 p 512. (b) Eaton, D. C. Loborul~rylnvestigotionr in O~gonicChemistry: McGraw-Hill: New York. 1989:p 36.1988 General Cotniogue. PCR Incorporated. Ic) Orgonir and InorganicChemicaisfor Research (1988Coiologus).Pfaitz& Bauer. Inc.Id) Gsnrra1 Cotologuo No. 9, Fairfield Chemical Company, 1988.
Chemistry in Action! "The Periodic Table Videodisc: Reactions of the Elements" "The Periodic Videodisc: Reactions of the Elements" is a 30-min videodisc containing action sequences and still shots of each element: in its most common form, reacting with air, reacting with water, reacting with acids, reacting with base, and in some common uses and applications. The videodisc has been published as Special Issue 1of Journal of Chemical Education: Softwareand may be ordered far 550 (555foreign).Purchasers will receive a singlesided, CAV-type videodisc and a Video Image Directory, which is an indexed list of codes from which to select frames, either for use with a hand-operated, remotecontrol device or for writing one's own computer control programs. Those who purchased Volume IB2 of JCE: Software; "KC? Discoverer" also received a program that allows them to control the videodisc through their MS-DOS compatible computers. Further details about the videodisc may be found on page 19 of the January 1989 issue of this Journal. To order: fill out the form below; make a check or money order payable to JCE: Software, Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706. Payment must be in US. funds drawn on a US. bank or by international money order or magnetically encoded check. -
--
Order Form Please send me lhe following:
-ThePedIMic Table VMawYdc:RWimsoftheElemenfs; $50 ($55 foreign), Includes videodisc and index of code numbers to frames on the disc.
I n f o r m a t i o n about other issues of JCE: Softwsrs.
City
506
Journal of Chemical Education
State
ZIP
