Fractional Distillation of a Binary Mixture

Purpose To demonstrate the technique for the separation of two volatile organic liquids. 

Cyclohexane and toluene are highly flammable, so be sure that burners are not being used in the laboratory. Use flameless heating (Sec. 2.9). 

Examine your glassware for cracks and other weaknesses before assembling the distillation apparatus. Look with particular care for star cracks in round-bottom flasks, because these can cause a flask to break upon heating. 

Proper assembly of glassware is important in order to avoid possible breakage and spillage and to avoid the release of distillate vapors into the room. Be certain that all connections in the apparatus are tight before beginning the distillation. Have your instructor examine your set-up after it is assembled. 

The apparatus used in these experiments must be open to the atmosphere at the receiving end of the condenser. Never heat a closed system, because the pressure buildup may cause the apparatus to explode  

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Steam distillation is for the separation of mixtures of tars and oils, and they must not dissolve much in water. If you think about it a bit, this could be considered a fractional distillation of a binary mixture with an extreme deviation from Raoult s Law. The water and the organic oils want nothing to do with each other. So much so, that you can consider them unmixed, in separate compartments of the distilling flask. As such, they act completely indepen-... 

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