Studies on Associated Solutions. II. Heat of Mixing of Methanol with Aliphatic Amines

The heat of mixing has been measured at 25.00°C and 45.00°C for binary mixtures of methanol with n-butylamine, diethylamine and triethylamine. A twin-type conduction calorimeter was used. All the systems exhibit large negative enthalpies of mixing, which become slightly less negative as the temperature increases. From the present results and vapor-liquid equilibrium data, the excess free energy and entropy of mixing at 25.00°C have been calculated for each system. The sign and magnitude of the excess functions were as follows: HM 0, TSE