Crib cards for tests

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teraction between science and technology, and a consensus has emerged that technological innovation most often evolves from prior technology, and that when pure science does play a role, its relation to the technological develo~mentsare seldom those of cause and effect. In a-careful study, for example, British technolo~icalinnovations of 196fiIfi7. of 84 s~~ccessful F. R. Jevons found the role of science to he a supporting, rather than an initiating, one and that in no single case was an innovation induced by a scientific discovery.' If we choose, as many of us do, to justify the pursuit of knowledge primarily by consequent tectkolo&al innovations, then the importanceof pure research will he diminished if,as seems likelv. .. the "iustifi(:ation is rendered iwalid. It is importaut for modern scientists, of whom chemists form a large percentage, to seek societal support for the pursuit of new knowledge as an integral part of the cultural attainments of mankind, a part moreover which encourages us to appreciate, utilize, and live in harmony with, the world around us. Melvyn C. Usselman Univelrsity of Western Ontario London, Ontario CanadaN6A587 Jevons, F. R., Technology 8 Culhxe, 17,729 (1976). Liability Insurance To the Editor: A contribution to the Safety Column last November by N. T. and Marilyn C. Kurnathl has pointed out the increasing numbers of law suits charging negligence on the part of laboratory teachers. This has raised questions about liability insurance for the financial protection of teachers and prompts us to call special attention to the ACS Professional Liability Insurance Plan, just in case our readers failed to note the paid advertisement on page A344 of that same issue. Reductions in rates have made this coverage a genuine hareain in the o ~ i n i o nof vour Column Editor. For Deace of minh and the protection-of your solvency we recommend writinz for full information. Address inauiries to the American Profesiionnl Agency, Inc., 95 Broadway, Amitpille, NY 11701. Whe plan also ~ncludrsroveraee for industrial chemists. and an alternative plan is available for consultants.) Malcolm M. Renfew University of Idaho

Soiled Chemistry To the Editor: There are significant agronomic errors in the experiment entitled, "Soil Analysis for High School Chemistry Students," by Mary A. Eisenmanu, published in J. CHEM. EDUC.,57,897 (1980). The Discussion section has several significant errors: 1) The fertilizer analysis 15-5-10 means 15%N, 5% P2Ob and 10% K20, not 5% P and 10% K as stated in the article. The state fertilizer registration laws are 20-30 years behind the times. 2) In soil that is too alkaline (basic) (pH 2 8), the micronutrients zinc. comer. iron. and manganese are tied uo as insoluble phosphates'and the'phospha& ions (~1'0,2-)'are unavailable because of the formation of insoluble calcium and magnesium phosphates. 3) In acidic soils (pH 5 5) the micronutrients (trace elements) maneanese and iron become too available and may reach toxic levels. Aluminum becomes a significant ~ r o b l e malso. The ideal soil DH is 6.5. the DH of maximum major and secondary nutrient availabilit; and proper micronutrient availability. A professional soil testing laboratory tests for the primary and secondary plant nutrients-N as Nos- by specific ion electrode, P calorimetrically as the blue phosphomolyhdate complex, and K, Ca, and Mg hy atomic absorption-emission spectroscopy. The micronutrients are also determined by AA. A soil lah does not test for HC03-. pH is measured with a pH meter. Na-Churs Plant Food Company analyzes approximately 130,000 soil sample a year for its fertilizer customers. I will he happy to answer any questions about soil testing, agronomic recommendations, fertilizer manufacture, etc. Walter C. Crouse Direclw, Roduct Research NaChurs Plant Food Company 421 Leader St. Marion, OH 43302

An Alternative Proof To The Editor: Carl W. David's article, "Why is an LCAO-MO Not Necessarily an Eigenfunction," which appeared in the April 1982 JOURNAL provided one demonstration that &id = Is. 1 s b is not an eigenfunction of the one-electron Hamiltonian H. I would like to suggest a much simpler and perhaps more interesting proof. Consider

+

MOSCOW. ID 83843

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Kurnath, N. T. and Kurnath, Marilyn C., J. CHEM.EDUC., 58, A329 (1981).

But Is, is an eigenfunction of the first two t e r n in H, and isb is an eigenfunction of the first plus the last term in H. In each case, the eigenvalue is simply the hydrogen-like atom ground state energy EHL= -(13.6 eV)Z2.Therefore Hls.

Crlb Cards for Tests To the Editor:

- Ze21rb)t.

= (EHL

Hlsb = (EHL- Ze2/?'a)lsb and

I would like to note that Whitmer's suggested use of a 3 X 5 "crib card" on tests [J.CHEM.EDUC.,60,85 (1983)l is not limited to physical chemistry. I have successfully used the same idea for several years in my sophomore organic chemistry course and I concur with Whitmer's comment that preparing the card is an excellent focus for study. I have had students complain that by the time they have figured out what they are going - - t o ~ uont the card thev no loneer need the card. I recommend-iw use by instructok intere&d in testing the use of facts without te~tingthe memorization of those facts.

It is impossible to factor the last two terms to yield simply +*id multiplied by a constant. Therefore, is not an eigenfunction of H. This proof exploits essential properties of the Hamiltonian H as well as of the AO's Is, and lsb, and offsets any need to consider specific functional details.

John Henderson Jackson Community College Jackson. MI 49201

Frank 0. Ellison University of Pithburgh Pinsburgh. PA 15260

266

Journal of Chemical Education

H&i* = E H L ( ~+s1sb) ~ - (Ze2/rd1s, - (Ze2/r.)lsb