Vapor pressure equilibrium of stearic acid in triglyceride and in high paraffin solutions

Summary The vapor pressure equilibrium of stearic acid has been determined at 180°C. in peanut oil and highparaffin solutions. Positive deviation from Raoult's law has been observed in both of the systems; it was however essentially stronger in the nonpolar high‐paraffin. Extrapolation of the vapor pressures obtained in paraffin to infinite dilution indicated that monomer stearic acid in free state would have a vapor pressure of 3.9 mm. Hg. at 180°C. in comparison with 0.80 mm. of the pure stearic acid itself, which is a mixture of monomer and dimer molecules. Quantitative relationships could be established between degree of association and vapor pressure. For pure dimeric acid at 180°C. a vapor pressure of 0.015 mm. Hg. has been calculated.