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WALTER A. WOLF Colgate Unlvsrslty Hamilton, New York
A Convenient Notation for Powers of Ten and Logarithms H. Oesterreicher University of California, San Diego La Jolla, California 92093 In the following, a convenient notation for numerical presentation and the concept of the power of ten is proposed which is used by the author in science classes. Accordingly, 10' is written 5, read x bar. By extension, we can write log a = b as a = 6. As an example, 1000 or 103 is written 3 (three bar). The familiar log 2 = 0.3 (which stands for 2 = 100.3) becomes The lattice parameter of Cu is written 3.6147 2 0 m, 2 = g. 103.6147. The decimal point can be or more didactically, . momitted by agreement. A welcome convenience of the "bar notation" is the possibility for omission of the customary prefixes such as kilo or terra. A terrameter (1012m) becomes a 12 bar meter, written 12 m. (Alternatively, this may be called a 12 p meter where p is a shorthand for power in several lan~uanes.)Ranee of disrances from the di-eter of the hydn&n nn"cleus(m.--5 1.3) to the extent of the universe (m 26 l.fi1 are expremed in a most compact fashion. Scientific calculations in the classroom and texts avoid cluttered expositions when performed in bar notation. An added advantage is the fact that no signs for multiplication are needed as the "bar"seoarates the numbers. As an examnle. the energy, k T (in ~oules);corres~ondin~ to 100Kis kT = 1.38 2 = J 1.38.
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A Demonstration in Solid State Chemistry: The Nonstoichiometry of Nickel Oxide, NiO Charles T. Perrino and Robert Johnson California State University, Hayward Hayward, 94542 It might surprise general chemistry students to know that nickel oxidecnn he prepared in nonstoichiometric proportions. While green nickelbxihe has the familiar formula-N~O,a grey material obtained from Baker Chemical Company has a ratio closer to Nio.980. A color transformation from grey to green can be observed and the extent of nonstoichiometry determined by a very simple experiment. If heat is applied to grey NiO a reaction oecurs which causes oxygen to he expelled from the compound. When the oxygen leaves the solid, some Ni3+ is converted to Ni2+ as the Law of Definite Proportions is approached as a limit. The dual oxidation state of nickel thus provides a means for the existence of the nonstoichiometrv. A 20-ml porcelain crucible and cover should be heated to a constant weiaht to f0.0005 a. Previouslv 2-3 e of mev NiO are dried in anoven a t 110°C f i r 1hr, as ~ 1 ; a0b s ~ r b s & i i t u r e from the air. When theNiO is cool, thesample is placed in the
crucible and weighed. With the cover off, the crucible is heated with a Fisher burner for 3-4 min (but not longer, to avoid sintering) or with a Bunsen burner for 1 5 2 0 min. This permits the color change to be readily observed by the students and instructor. When the heating is completed the crucible should he cooled with the cover on in a desiccator and weiehed. In the event that some sample still has the grey color the procedure should he repeated. Dependinn on the sample size approximately 0.01-0.02 g of oxygen will be driven bff and the nonstoicbiometry may be calculated.
A Simplification for Obtaining Russell-Saunders Term Symbols E. A. Castro Institute de Inuestigaciones Fisicoqubmicas Tedricas y Aplicadas, Sucursal4-Casilla de Correo 16 lgOOLa Plata-Argentina The method for obtaining Russell-Saunders term symbols described by K. E.Hyde [J. CHEM. EDUC.,52,87 (1975)l may be simplified without introducing any substantial change. Once the major array is constructed to testing to see that every microstate is included, the procedure consists in eliminating all ML and M s values (a subarray) that belong to a particular term, thus producing a new major array. This process is repeated until the major array vanishes. But the major array is doubly symmetrical in the sense that a) for a given ML the number of microstates is equal for M s and -Ms. and b) for a given M s the number of microstates is equal for MI, and -ML. It is then enough to work with non-negative M L and MS values in order to make the successive subtractions of terms. The simplification of the process makes it a quick task to ohrnin Russell-Saunders term ssmbols from electronic configurations. Copies of the simplified procedure for different electronic configurations are available upon request to the author.
Biochemistrv Laboratorv Ex~eriments Jeffrey A. Hurlbut Metropolitan State College Denver, Colorado 80204 The introductory biochemistry laboratory is a difficult course to teach because of several factors. The students have varied hackgrounds; the equipment and chemicals are expensive; the instruments are in constant demand; the class sizes are large; and there are few biochemistry laboratory manuals. Because of these factors we devised our own biochemistry laboratory scheme. This laboratory scheme consiswd of ten exwriments from which the studentssel~ctedanv four during the quarter, developed their own performed the experiments, and reported the results. Were~
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Volume 54, Number 6, June 1977 1 367
cently changed thin laboratory hy adding new experiments, updating the old ones, and by including the detailed procedures. These experiments include the following: Blood Glucose Determination. Ion Exchange Amino Acid Senaration. Casein and ~lbumin'lsolation,~rb;teinPhysical and khemical P r o ~ e n vI)etrrmination. Protein Gel Chromatorraohv Seoaraiion; Carbohydrate '~dentification,pH-TemperatureInhibitor Enzyme Activity Effects, Km-V,.. - k,,t - ki Determination, Ground Beef Lipid Isolation and Determination, Salivary Alpha Amylase Characterization, and Electrophoretic Serum Protein Separation. We would like to make a COPY of our lahoratow manual available to those who are interested. We have hadexcellent results with this new approach to the upper division bio.. chemistry laboratory.
Compact Compacts Steven L. Murov of Sangamon State University in Springfield, Illinois points out that in many organic chemistry laboratory manuals the synthesis of triphenylmethanol is used as the example of a Grignard synthesis. In some manuals the
368 1 Journal of ChernicalEducetion
synthesis is performed via the addition of the phenyl Grignard reagent to benzophenone and in others to methylbenzoate. If students are divided into two groups, one of which uses henzophenone and the other methylbenzoate, a comparison of yields, time consumption, chemical costs, and the resulting economics of the reactions can be the goal of the experiment. The use of rhemical catalogs and the economic comparison of two possible synthetic routes should make this a unique. interesting, and educational experience for the students. Ralph E. Truitt and Jeffrey Dimmit of the University of New Hampshire state that recovery of silver from argentometric halide determinations, is worthwhile in view of the cost of silver nitrate reagent, pakicularly if these experiments are repeated regularly. As an alternative to an ion exchange method recently proposed IRenganathan, S., and Mehta, H., .I. C'HEM. HDIJC.. 53.347 (1976J1,the silver may be recovered by adding a reducing agent to thk silver halidedissolved in 3 M ammonium hydroxide. Some effective reducing agents are zinc or copper, which can he immersed in the solution until reduction is complete, or sodium horohydride. The metal formed is collected by filtration, washed with water and dissolved in 3 M HN03. Silver nitrate crystals are obtained by evaporation.
