Determination of the dipole moments of some polar liquids dissolved in polar solvents

• Published in: Canadian journal of chemistry 1969-10, Vol.47 (20), p.3767-3771
• Main Authors: Rizk, H. A, Youssef, N, Grace, H
• Format: Article
• Language: English
• ISSN: 0008-4042; 1480-3291
• DOI: 10.1139/v69-628

The application of a modified form of the Onsager equation at the condition of infinite dilution of a polar solute in a polar solvent leads to reasonable dipole moments for water, pyridine, acetone, tert-butyl alcohol, n-butyl alcohol, and β-octyl alcohol, except in the case of water in tert-butyl alcohol at 30 and 40 °C and the case of acetone in n-butyl alcohol at 30 to 50 °C. The initial decrease of the dielectric constant of solvent by addition of solute in each of these two cases is associated with a reduction in the Kirkwood g-factor of solute. In all 12 systems investigated, strong hydrogen bonding occurs between solute and solvent molecules and often between solvent molecules themselves. It is thought that this equation must fail when short-range interactions assume predominant importance, but why it works so well for those cases which are also strongly interacting systems is not clear.