Abstract
Some of the roost important reactions of chemistry involve substances, not in the pure state, but in solution. Consequently, generalizations, whereby the behavior of substances in solution may be predicted, are of the utmost necessity for the advancement of chemistry. Until recently, in the formulation of the laws of solutions, it was the custom to consider only the physical end chemical properties of the solute and neglect the properties of the solvent. This custom was without doubt, due to the fact that the study of most chemical reactions involved substances dissolved in the same medium, namely water. Since the advent of the Bronsted concept of acids and bases and the Debye-Huckel theory of electrolytes, the study of chemical reactions in solution has been extended to reactions that take place in non-aqueous solvents. |In predicting the behavior of substances dissolved in a certain solvent it is necessary that something be known of the nature of the solvent. In the ease of salts, probably one of the most important factors to be considered is the dielectric constant of the medium. However, in the case of acids, it would seem from the viewpoint of the Bronsted concept that the basicity of the solvent is of primary importance and the dielectric constant secondary. This prediction is shown to be a fact from a consideration of a few examples. Water and nitrobenzene are two liquids having high dielectric constants. later is a strongly basic solvent and nitrobenzene weakly basic. Hydrogen chloride is very soluble in water and forms an ionized complex with the solvent. However, in nitrobenzene the solubility is low and an unionized complex is formed between acid and solvent. On the other hand dioxane and acetic acid are two liquids having low dielectric constants. Dioxane is a much stronger base than acetic acid. In dioxane the solubility of hydrogen chloride is high while in acetic acid the solubility is only moderate and an unionized complex is formed.