Isomer effects in mixtures of hydrocarbons: some experimental excess volumes and enthalpies

Abstract

Excess volumes have been measured at 293.2 K for n- hexadecane+cyclopentane, +methylcyclopentane, +cyclohexane, +methylcyclohexane, +trans-1,4-dimethylcyclohexane, and +2-methyl- butane, and at 298.2 K for n-hexadecane+2,2,4-trimethylpentane. The corresponding excess enthalpies have been measured at 298.2 and 308.2 K for n-hexadecane+cyclopentane, +methylcyclopentane, +cyclohexane, +methylcyclohexane, and + 1,4-dimethylcyclohexane. Excess volumes have been measured at 298.2 K for all ten binary mixtures of cyclohexane, methylcyclopentane, n-hexane, 3-methylpentane, and 2-methylpentane; the systems cyclohexane+methylcyclopentane and n-hexane +methylcyclopentane show double minima in the curve of V^E against x and have been measured at two lower temperatures as well. The excess volumes show a consistent trend towards more negative values as the number of methyl groups increases; the excess enthalpies are more difficult to interpret.