THERMODYNAMICS OF TERNARY MIXTURES EXHIBITING TUNNEL PHASE-BEHAVIOR .2. N-HEXANE-N-DECANE-PROPANENITRILE

The shape of the two-liquid-phase coexistence region in the phase pris m of the ternary mixture n-hexane-n-decane-propanenitrile has been det ermined by measurements of phase-separation temperatures for mixtures in three quasibinary slices each with constant n-decane:n-hexane volum e ratio. These results were used along with the coexistence curve resu lts of Arriaga-Colina, McLure, Clements and Hill for the binary mixtur es n-hexane-propanenitrile and n-decane-propanenitrile to characterise the topology of the composition-temperature ternary phase diagram. A crude method for the estimation of the tielines for the n-decane: n-he xane volume ratio = 3:1 quasibinary slice has revealed that they do no t lie in the plane of the quasibinary slice. Furthermore, the position s of the tielines change with temperature, tending at higher temperatu res to become more parallel to the nearer binary face of the phase dia gram.