Excess molar volumes of some partially miscible liquid mixtures

Excess molar volumes VmEhave been determined for (formic acid + benzene, or toluene, or p -xylene) at T = (298.15 and 308.15) K. The aromatic hydrocarbons form two liquid phases with formic acid over different ranges of composition. The value of VmEis positive for all the mixtures and varies as benzene > toluene > p -xylene. The derivativedVmE / dT is also positive.