Ionization of Strong Electrolytes. III. Proton Magnetic Resonance in Nitric, Perchloric, and Hydrochloric Acids

Since the proton magnetic resonance shift in an acid is a colligative property, the derivation of degrees of dissociation requires assumptions which cannot be tested directly. Results derived from measurements of this resonance shift in nitric acid and in perchloric acids are in sufficient agreement with earlier results obtained from a specific property (intensity of Raman lines) to confirm the interpretation of the shift. The value 22 has been found for the thermodynamic dissociation constant of nitric acid, the value 38 for perchloric acid. The association of nitric acid in aqueous solutions containing more than 50 mole percent of acid is reflected in the shift. Differences in the limiting slopes of the resonance shift of the proton in various acids at high dilution are interpreted as due to different influences of the anions on the association of water.