Effect of Alkyl-Chain Branching on the Partial Molal Volumes of Organic Salts in Aqueous Solutions

Abstract

The densities of dilute aqueous solutions of 1, 1, 3, 3-tetramethylbutylammonium chloride and sodium 3, 5, 5-trimethylhexanoate have been determined at 5, 25, and 45° using a buoyancy technique. The apparent and limiting partial molal volumes of the salts have been derived. The partial molal volume of branched-chain isomer is smaller than that of corresponding straight-chain isomer as well as the calculated value. The results have been compared with those for the isomeric butylammonium and butanecarboxylate salts. The effects of hydrophobic and ionic groups on the structure of water have been discussed.