Molar excess volumes of binary liquid mixtures: 2-pyrrolidinone with C6–C10n-alkanols

The excess volumes VE of the binary mixtures 2-pyrrolidinone–(C6–C10) n-alkanols have been calculated from density measurements over the whole composition range and the 298.15–318.15 K temperature range. The excess volumes were independent of temperature, but changed noticeably with the chain length of the alkanol. The VE values were only positive starting from heptanol, with the maximum value, 0.239 cm3 mol−1, for equimolar decanol. The observed changeover VE < 0 to VE > 0 suggests that the steric effect is primarily responsible for the positive contributions to VE. The thermal expansion coefficients α were evaluated from the variation of densities with temperature. Key words: excess volumes, 2-pyrrolidinone, n-alkanols, liquid mixtures, hydrogen bonding.