Excess enthalpies of binary mixtures of cycloheptane or cyclooctane with benzene or toluene or ethylbenzene at 298.15 K

Abstract A flow microcalorimeter of the Picker design was used to measure excess molar enthalpies H E at 298.15 K, as a function of the mole fraction x 1 , of the binary liquid mixtures cycloheptane (c-C 7 H 14 ) + benzene (c 6 h 6 ) or toluene ( C 6 H 5 CH 3 ) or ethylbenzene (C 6 H 5 C 2 H 5 ), and cyclooctane (c-C 8 H 16 ) + benzene or toluene or ethylbenzene. The calorimeter was equipped with separators and operated in the discontinuous mode. In each series, H E is largest for the mixture with benzene, and smallest for the mixture with ethylbenzene. For instance at x 1 = 0.5, H E /Jmol −1 is 821 for c-C 7 H 14 + C 6 H 6 624 for c-C 7 H 14 + C 6 ,H 5 CH 3 , and 548 for c-C 7 H 14 + C 6 H 5 C 2 H 5 . For any given aromatic component, H E of the mixture with cycloheptane is slightly larger than H E of the corresponding mixture with cyclooctane. The results are discussed in terms of the simplest version of the KGB theory.