ing new
Edited by: JOSEPH S.
SCHMUCKLER
Chairman of Science Education Temple University 345 Riner Hall Philadelphia.PA 19122
The procedure is clearly stated and expected results are given. "Tackling t h e S i x t h State," H e n r y T e a c h e r , 73, (February 1975). properties of liquids (I), the transport oE matte;, energy: and momentum in liquids (II),and the electronic properties of liquids (1111." Rice presents a . . nonchemical survey of the molecular interpretations of a variety of properties of the liquid state." Though far from a complete theoretical presentation, Rice creates. . ."simple pictures which enable all phenomena to be interpreted in terms of molecular and electronic motions."
".
Solutions "Minerals i n Water," H e r b e r t A. Swenson, T h e Science T e a c h e r , 32,17-21, ( J a n u a r y 1965).
H. Kolm, T h e Physics
Matter was traditionally considered to exist in three states of aggregation: solid, liquid, and gas. Two additional states have graduallv achieved recognition: the fourth. the vlasma state exists wher. ever the mean free path in a gas is long enough to permit an electron to acouire ionizing" enerev in the orevailine electric field before it collides with a molecule (notably in the ionosphere, in neon tubes, and in arc lamps); the fifth, the superfluid state, exists where thermal energy is sufficiently scarce to permit molecules to condense in momentum space (in liquid helium below 22°K); the sixth, the colloidal state, has still been largely ignored except by a handful of experts. I t exists when a solid (or liquid) is so finely divided that electrostatic forces overwhelm both eravitational and surface forces and com~letelv
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"A drop ofwster varies in size, dependingupon such properties as specific gravity, viscosity, and the conditions under which the drop was formed." Swenson discusses taste thresholds of dissolved materials by human beings. "Natural water is a dilute electmlytie solution of elements dissolved from the earth's crust or washed from the atmosphere." A table shows the range of dissolved solids in representative natural waters. Another table shows the chemical composition of rainwater from several localities of the U.S. For the teacher interested in the current problem of "acid rain," here is an excellent base line data source that is almost 20 years old.
somewhat loosely to very finely divided matter in general
"Probing Concentration Zero," Howard A. S t o r m s a n d William Tichy, C H E M I S T R Y 46,6-10, ( M a r c h 1973).
The construction of a very useful teaching aid is pictured in the article. For my own teaching, I have constructed a similar model on a larger scale. Instead of steel ball bearines. mv modeluses elass heads.
Kolm goes on to discuss several colloidal effects of importance including newer river delta formation and the irreversible solidification of latex mint The article is short. hut it contains useful ideas that impinge on current chemical pollution problems. "Hollow L a n t e r n Slides Illustrating Crystal Structure," Malcolm E. K e n n e y a n d Selby M. Skinner, J. CHEM. EDUC., 3 6 , 4 9 5 (October 1959).
In October of 1971, the world's most sensitive chemical analysis was done. Twentv million atoms of Plutonium-244 were detected. a conthe construction of asecond model that includes "impurities" in the crystal lattice. Both models are not difficult to construct. tering spectrometer which measured the energy change of the impinging ions when they collide with surface atoms. The authors describe in good understandable language the techniques used and the results obtained.
" 'Some'
R e a l Life "Applications of Solubility,' " R o b e r t C. B r a s t e d , J. CHEM.EDUC., 47,634-635 (September 1970).
"Iron. Iron Evervwhere hut Not a Dmo to Drink." Pineaooles.
discussed with respect to iron. HaZ+is not healthful, but you can "qua? a BaSOa cocktail for an X-ray study of your internal plumbing. Why? This article includes several other examples of the various applications of solubility. " T h e Solubility Curve of Boxax: A S t u d e n t Laboratory E x 35,364-365 periment."Robert D. E d d y , J. CHEM. EDUC., (July 1958). In lieu of the usual first lab experiment in titration, Eddy has developed a volumetric procedure that allows quick and easy development of a solubilitv curve. Readilv available, inexpensive chemicals are used. If one chooses. the ~ m c e d u r ecan amvide "an excellent oovortunitv .. for a discussion on the choice of indicator, and on the mdieatar problem in general."
64
Journal of Chemical Education
"Leisgang Rings," H u b e r t Alyea, T O P S , J. CHEM EDUC., 46, A843 (November 1969). The formation of Liesgang rings provides a demonstration which, although I have done i t many times, still continues to fascinate me. Petri dishes can be substituted in lieu of the suggested equipment. Dr. Alyea suggests placing one drop of the AgNOdaq) in the center of the system. I would also suggest trying off-center innoeulations. In addition, try using a vertical system, such as a test tube. The results are intriguing. Those of you who are familiar with the alternating dark and light green bands seen in Malachite, might consider if these hands are Leisgang rings?
"A Device for Demonstrating Conductivity of Solutions," Fred B. Eiseman, J. CHEM. EUUC., 33,445, (September 1956). Eisernan's desien of a eonductivitv anoaratus ". . .makes it oossible the solutions and is ready lor instant use ..r,xon n r .ne; mlrwa' .,I., . f . ~ ~ t ~ c . , f ~ o r n01s p ~ c5 .5 . e ~ o l i r e 0 . R ~ A a- m omer sc I:, :c ' L C ! , nc o ~ n ,i Top cs 6 .Y presrrue" n m e SF.(: J V .r I J . I,. . m ~;wF . m e ton : s .: ..yn: I ',p cc !I gn school curriculum. TIIS
