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CHEMISTRY: KEYES AND WINNINGHOFF
CHANGE OF THE IONIZATION OF SALTS IN ALCOHOLIC SOLVENTS WITH THE CONCENTRATION By Frederick G. Keyes and W. J. Winninghoff RESEARCH LABORATORY OF PHYSICAL CHEMISTRY. MASSACHUSETTS INSTITUTE OF TECHNOLOGY Received by the Academy, May 8, 1916
The deviation of
largely ionized substances, even in fairly dilute so-
lution, from the mass-action law, and in general from the behavior of
perfect solutes, has been the subject of extended discussion among physico-chemical investigators. Evidence is accumulating that at sufficiently small ion-concentrations these substances become normal in their behavior. Thus Kraus and Bray1 showed that uniunivalent salts dissolved in liquid ammonia and in certain organic solvents conform to
the mass-action law when the concentration of the ions in the solution lies below about 0.0001 normal in ammonia, 0.0005 normal in organic solvents; and Arrhenius2 has made recalculations with the data of Kohlrausch and Maltby on the conductance of aqueous solutions of sodium chloride and nitrate which indicate that these salts behave as perfect solutes in water at concentrations between 0.00002 and 0.0002 normal. A great variety of expressions have been proposed to account for the deviations at higher concentrations. Of these the one which is most generally applicable is that proposed by Kraus and discussed fully by Kraus and Bray.3 Kraus and Bray have shown that the conductance of almost any uniunivalent solute in any solvent from the concentration zero up to a fairly high concentration (one where the change in the viscosity of the solution becomes an important factor) can be expressed by an equation of the form:
(C-Y)2 K+D(cD)m. In this equation K, D, and m are empirical constants which vary with the nature of the solute and of the solvent and with the temperature, and y repre