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WALTER A. WOLF Eisenhower College Seneca Falls. New York 13148
Notation for Powers of Ten Robert D. Freeman Oklahoma State University Stillwater, 74074 Oesterreicher's note (J. CHEM. EDUC., 54,367 (1977))on a convenient notation for powers of ten prompts this description of what I believe to he a simpler scheme. The proposed notation is a variant of the widely used "E" exponential notation in Fortran, in which 6.624 X is represented by 6.6243 - 27. The variation is to replace "En and the sign by an appropriate letter: "P" for positiue exponents, " N for is then written negatiue exponents. The number 6.624 X as 6.624N27, and 6.022 X loz3is written as 6.022P23. The advantaees claimed bv Osterreicher for his "bar notation" appl&qually to this notation. The PIN notation has these further advantages: i t is easier to write and to type than is the "bar" notation; the sign of the exponent is emphasized by the use of two letters; the letter is less likely to be overlooked or misread than is the "bar" notation with and - symbols; and, finally, the PIN notation is closely related to the " E notation of Fortran which many students either already know or will need to learn.
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weight. In the determination of molecular weight the term paper covered such topics as the theory and methods using colligative properties, mass spectrometry, viscosity of polymeric materials, centrifugation and sedimentation equilibrium. The third student, who had to identify functional groups, dealt with the theory and practices of infra-red spectroscopy, proton magnetic resonance, visible and ultra-violet spectroscopy. In addition potentiometric methods were used for the determination of ionization constants of weak acids or bases. The last student in each group had to put all the information together and "run" any additional experiments to determine the molecular structure. In the case of the "Sea Snake"gn)up, the student presented n paper on peptide hydrolysis and methods of amino acid sequencing.The other two groups gave discussions on mass speciroscopy and fragmentation patterns and all groups gave the molecular structure of an isolated materiallproduct similar to the compounds they were assigned. Thus, each group had given the theory and methods of characterizing a natural product and each term paper was different. During the final portion of the quarter, each student performed a laboratory experiment which was discussed in his/ her own term paper.
A Physical Chemistry Project Involving Natural Products J a c k Steele Albany State College Albany, Georgia 31707 One problem encountered in teaching upper division courses is trying to relate seemingly isolated topics in general, organic, analytical, and physical chemistry into a coherent overview of chemistrv. One oossible aooroach to remedv the students' compartrnentalizaiion of knowledge is the use df the term paper coupled with a set of laboratory experiments during the last quarter of physical chemistry. Based upon a random drawing, the students were divided into three groups of four each. The "Sea Snake" group was assigned the task of isolating and characterizing a polypeptide from snake venom. The "Pokeroot" group had to isolate and characterize a plant alkaloid, and the "Periwinkle" group had to characterize any alkaloid, hormone, or peptide for possible drug use. The first student in each erouo - . had to choose a method of extraction, isolation, and purification that was appropriate for his molecule or com~ound.Thus. the "Sea Snake" .. erouo's . expert had to discuss, give basic theory and deriw equations for ionic mohilitv and movinr boundary methods, as applied to e l e ~ t r o ~ h o r e sThe ~ s . othe;groups uied solvent extr&tion and chromatographic methods which included discussions of Henry's Law and the Nernst distribution equation. The next "expert"in each group assumed that helshe had been given pure compound and had to determine melting point, optical activity, percent composition, and molecular
Calorimetry and Solar Energy R. B. Shiflett Campbellsuille College Cambellsuille, Kentucky 42718 The intensified interest in solar energy due to the energy crisis can be used to add relevance to the calorimetry experiments in most general and physical chemistry laboratory sequences. One proposal for the storage of solar energy involves heating a hydrate such as Na2S0~10HzO.Sufficient heat results in the reaction, NazS04.10H20 Na2S04 10HzO. The reverse reaction will release the heat of hydration (stored solar energy). The experimental method for calorimetni described in most general or physical chemistry laboratory ianuals can he used to measure the heat of hydration. After determinine the heat capacity of the calorimeter, students then measure the heat of solution of NazSOalOHsO a t a dilution of 400 (1mole of hydrate per 400 moles of water). Next the heat of solution of the anhydrous salt is measured a t the same dilution. The anhydrous salt is obtained by drying a sample of the hydrate in the sunlight. If weather conditions do not permit, a heat lamp may be used. The difference in the heats of solution is the heat of hydration. Our average values for the respective heats of solution were -2.4 kJ1mol and +72.9 kJ/mol yielding a heat of hydration of -75.3 kJImol. The heat of hydration represents the "stored solar energy".
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Volume 55, Number 2 Febroaw 1978 1 103
