CHM 2211L Lecture Notes - Lecture 99: Steam Distillation, Fractional Distillation, Silica Gel
30 Jun 2017
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Simple distillation: used for 90% or purer cmpds. or non-volatile ones. *distillation at lower pressures can be done for both steam and simple used if a cmpd. is too large or would deteriorate under too high temperatures. Steam distillation: co-distilling an organic cmpd. along with h2o. *advantages: desired material will distill below 100 c even if had bp above that. In an immiscible mix, each component exerts its own full pvap independently of other components present or molar fraction. The mix will boil at lower temperature than that of any of its components. B/c water will have the lowest bp, its pvap at a given temperature will be large (say 733mmhg) thus the other component only requires pvap of 27mmhg for mix to reach 760mmhg and evaporate completely. Subsequent separation of mix is facilitated by insolubilities. H2o (total pvap = vapor pressures of each component as if they were by themselves.
