Correction of Debye Theory
The sixth-most cited paper in the Journal of the American Chemical Society, "Electric Moments of Molecules in Liquids," was submitted in 1936, paving the way to a better understanding of polar liquids.
Yale University professor Lars Onsager first sent his paper on electric moments of molecules in liquids to Physikalische Zeitschrift, a journal edited by Petrus J. W. (Peter) Debye, but Debye turned it down. John G. Kirkwood, then a research fellow with Debye in Leipzig, convinced Onsager to write an English version and submit it to the Journal of the American Chemical Society, which published it [J. Am. Chem. Soc., 58, 1486 (1936)].
The paper, which is the sixth most highly cited JACS paper, corrected Debye’s formula relating the dielectric constant of a polar substance to the molecular dipole moment. Debye’s formula includes the polarizability of the molecule, its permanent electric moment, the dielectric constant, and the energy of thermal agitation. Onsager served as a research assistant for Debye from 1926 to 1928.
“Debye’s original theory is still used today to determine dipole moments of molecules dissolved in nonpolar solvents by measuring the dielectric constant of the solution,” says John F. Kauffman, a chemistry professor at the University of Missouri, Columbia.
The problem was that Debye’s formula didn’t work for polar liquids. “At the time,” Kauffman says, “a common explanation was that ‘association effects’ due to dipole-dipole interactions could not be properly accounted for in the Debye theory. Onsager sought to correct this misconception by performing an analysis of the interaction of a dipolar solute molecule with the electric field that is produced as the result of the polarization of the surrounding solvent by the solute molecule.”
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Excerpted with permission, Chemical & Engineering News
Copyright © 2003 American Chemical Society