FLASH POINT STUDY OF BINARY NONAQUEOUS MIXTURES OF LIQUIDS WITH POSITIVE AND OF NEGATIVE DEVIATIONS FROM THE RAOULT’S LAW

Flash points of three systems butanol-1 (BA) + dimethylsulfoxide (DMSO), 2-metilpropanol-1 (MPA) + n-pentadekan (PD) and ethylene glycol (EG) + dimethylsulfoxide are experimentally measured. The choice of mixtures is caused by the positive (BA– DMSO, MPA– PD) and negative (EG – DMSO) deviations from Raoult's law. The hypothesis according to which on the dependence of the flash point of the composition of the mixture can be observed maxima in the case of a negative deviation from Raoult's law and minima in the case of a positive deviation from Raoult's law is confirmed. Flash point of the mixtures EG + DMSO, containing 0.2–0.4 mole fraction DMSO, on 3–4 degrees above the flash point of nonvolatile component (EG). Among the investigated mixtures systems with a minimum of flash point are not detected. Flash points of mixtures studied in the approximation of the ideal solution have been calculated. Based on the data obtained, the assumption that for mixtures with a strong deviation from the ideal solution properties the sign of the difference between the calculated and experimental flash points corresponds to the sign of the deviation of vapor pressure from Raoult's law has been made.