Theoretical Approach on W-Shaped Excess Heat Capacities of Some Linear and cyclic OxaalKane-AlKane Systems

The excess heat capacities, cpe, throughout the entire concentration range have been determined at 30 °c, 40 °cand 50 °c of linear and cyclic oxaalkane systems : 2,5,8,11,14-pentaoxapentadecane (tetraglyme) with dodecaneand 1,4 dioxane with dodecane .for all these mixtures cpe has a w shaped concentration dependence (two minimum speared by amaximum). by decreasing the molecular size of their component, the second minimum towards highconcentration disappear at 30 °c and 40 °c but persist at 25 °c.cpe behaviour correlates with degrees of non-randomness in the mixtures as quantified by theconcentration-concentration correlation function scc witch is calculated using quasichemical guggenheim-barker-kehiaian theory with a group-interaction model and assuming interaction between molecular surfaces[2].the selected linear and cyclic oxaalkane-alkane systems studied; accordingly, the influence oftemperature, the size and molecular structure on the excess heat capacities has been analysed.