J. A. CAMPBELL HaNey Mudd College
Claremont. California 91711
Questions 6303. Suhmitted by Dr. Jerry Ray Dias, University of Missouri-Kansas City. Given the recent data in the table, comment on the sources and relative amounts of the various ions itemized. In view of EPA's goal to eliminate all metal ion discharges (from industrial sources) discuss these recent results. Sources of Metals Discharged t o N e w York Bight Sewage Plant cuZt Raw Water Supply, % industry. % c i t y Runoff,% Reridential. % Totals, Ibllday
20 19 14 47 3.540
cr3+
~
i
~ zn2+ +
cd2+
0 52 9 28
0 65 10
7 20
39
25
2,060
1.545
42 5.420
12 49 240
31
0
Data from L. Klein, M. L a m . N . Narh, and 5 . Kirrchner presented at the N Y Water Pollution Control Arrociation Conference on January 21.1974. to be published by the Journal Water Pollution Control Federation.
6304. Calcium disodium edetate (EDTA) is a specific antidote for lead poisoning. T h e dissociation pK's of EDTA and Na+, Ca2+, and Ph2+ are, respectively, 1.7,10.6, and 18.2. Why not use the tetrasodium salt in treating lead poisoning? 6305. A good correlation is observed between olive oil/ water partition coefficients and ability of a non-electrolyte to penetrate biologic membranes, e.g., skin and cell walls. High penetrating ability goes with high solubility in olive oil com-
pared t o water. An approximate equation is: (permeability constant) = 10 X (partition coefficient). However, molecules smaller than about 15 A in diameter and molecules larger than 30 A in diameter often show much ereater or smaller Denetrating power, respectively. Why? [ ~ o h n d e rR., , and ~ G l u n d , H., Acta. Bot. Fenn, 11.1 (1933)l. 6306. Acute phenobarbital ( p ~ .= 7.2) poisoning may h e overcome in about 1/15 of the untreated time hv administering intravenousaqueoussodium bicarbonate which raises both hluodpH (nurmally 7.4) and urinepH (normally about 6 t o 8.0). Comment on the chemistry of barhiturateiemoval. 6307. Unlike drugs, which are found mostly hy trial and error, antidotes are often synthesized on a rational basis from the known properties of a poison. T h e first example of such a synthetic antidote was dimercaprol, CH20H CHSH CH2SH, synthesized a s a n antidote against the war gas Lewisite, C12AsCH=CHCl, whose active site was the arsenic atom. Suggest the rationale. 6308. Two of the most common forces in nature are electrical and nravitational. You mav eet some insieht into their relative c k r i b u t i o n s t o atomic structure by c a h a t i n g the ratio of the electrical revulsion force between two electrons t o the gravitational attraction between the same two electrorIS. Richard Feynman in "The Character of Physical Law" [MIT Press, 19671 gives a value of 4.16 X
Answers A303. Cu2+ is added to the water sunnlv .. . to control deal " gnwth. Cu'* from residential sources is m a t likely due toropper plumhing. If m e assumes that equal quantities of metallic Cu ( \ W = 63.51 and %n(M\V = 65.4,are used in our technology (e.g.. in brass) one would expect greater runoff and residential discharges of Znz+because of the greater reactivity of metallic Zn over the nobler Cu. Zn also is much used in galvanized products (like roofs), is more abundant on the earth's crust than Cu, Ni, and Cd, and does have the highest total discharge. Since Cd2+is the most toxic of the above ions, its use in our society, and consequently its total discharge,is least. Industry is not the principal polluter for moat of the listed metal ions; residential sources are the principal dischargers of Cu2+. Zn2+.and Cd2+.Thus if any metal ion is found to be hazardous, it should he dealt with in terms of actual sources rather than merely imposing a zero discharge level on industry. A304. The tetrasodium salt will comolex too much Ca2+and deplete the lmdy stocks. The calcium disodium salt does not complrx further Ca2- but does tw up the Ph'., releasing ('a'', as you sce from the pK values. Rememher each EDTA mdecule complexes only one M2+ ion. A305. The eo~elationof penetrating power with partition coefficient is consistent with the existence of a lipid barrier between the aqueous phases and the two sides of the skin harrier. If effective molecular mobilities are constant and the lipid-aqueous phases are near equilibrium, the observed correlationis reasonable. Large molecules, however, will have low mobilities through the semi-rigid lipid layer, whereas small molecules will be much more mobile. Thus one must add this relative mobility effect to the equilibrium distribution effect to account for the observed data. A306. At pH 8.0 phenobarbital will he primarily in its anionic form and relatively more soluble in water (blood and urine) than in lipids (fats and similar body tissues). Thus the blood of pH 8.0
will extract the barbiturate from the bod" tissues and the kidnev will transfer it to the urine for excretion. Note that .~ . the ionic to .. neutral form roncentrativn rati
