The vapour pressures of water + 2-aminoethanol, + N-methyl-2-aminoethanol, and + N,N-dimethyl-2-aminoethanol at 298.15 and 308.15 K were measured over the whole composition range by a static method. The excess enthalpies and densities of the same mixtures at 298.15 K were also measured with an isothermal displacement calorimeter and a pyknometer. The thermodynamic excess functions: GE, HE, TSE, and VE were calculated. Except for aminoethanol-rich region in (water + N,N-dimethyl-2-aminoethanol), where GE is slightly positive, the signs and relative magnitudes of molar excess functions were 0 > GE>TSE>HE, VE < 0. These are in accordance with general characteristics of (water + a highly hydrophilic compound). However, hydrophobicity is clearly seen for dilute aqueous solutions where the partial molar volume of aminoethanol exhibits a minimum and the partial molar enthalpy decreases rapidly to a limiting value at infinite dilution. This tendency increases with the introduction of methyl groups into 2-aminoethanol.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Physical and Theoretical Chemistry