Partial molal volumes of n-alkylamine hydrochlorides in methanol-water mixtures

The apparent molal volumes() of the homologous salts , where R varies from methyl-() to n-butyl-(n-) in a series of methanol-water mixtures have been determined at 30 by means of a float method to fifth decimal places down to 0.01 m. The values of extrapolated to infinite dilution give partial molal volumes which varies considerably in accordance with the solvent composition. that is, mole fraction of methanol. The experimental results are discussed in terms of the varying size and charge effect, hydrophobic nature of the solute species, and also the additivity relationship between successive homologous and the structure of the binary solvent. The results indicate that at 0.1 mole fraction methanol the enhanced structuredness of water cause a minimum in the partial molal volumes of cations , while at 0.4 mole fraction the solvent structure is such that the free volume is a minimum but the effect of electrostriction is a maximum.