Abstract
Excess enthalpies, excess volumes, and excess isentropic and isothermal compressibilities, have been determined at 298.15K for binary mixtures of dimethylacetamide (DMAC)+an alkane (CnH2n+2, n=6∼9) and+cyclohexane. The phase separation was found for these mixtures, except for the cyclohexane mixture. Excess volumes are positive for these mixtures, except for the higher mole fraction of the hexane mixture. On the other hand, excess compressibilities for these mixtures are large and negative. This is unusual behavior in relation of excess volume to excess compressibilities. The results are discussed in terms of contributions from not only the dipolar-dipolar interaction in addition to the dispersional interaction but also the change of the molecular packing between the pure and the solution states.
