Fundamental Organic Chemistry
Fundamental Organic Chemistry
Fundamental Organic Chemistry
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The above process is to be repeated many times before the vapor consists<br />
only pure ethanol. During the process the escaping vapor is measured by a<br />
thermometer of the fractionating column. The temperature will remain steady for<br />
some time and will then rise quickly and become pure ethanol.<br />
When the ethanol has boiled off completely, the escaping vapor will consist of<br />
pure water only.<br />
Generally, for fractional distillation to work best, the difference in boiling points<br />
of liquids in the mixture should be greater than 10C. The separation will not be<br />
complete if it is not.<br />
Fractional distillation is used in industry to separate oxygen and nitrogen from<br />
liquid air. In whisky production it is used to increase ethanol.<br />
2-Vacuum distillation<br />
Vacuum distillation is a method of distillation whereby the pressure<br />
above the liquid mixture to be distilled is reduced to less than its vapor pressure<br />
(usually less than atmospheric pressure) causing evaporation of the most volatile<br />
liquid(s) (those with the lowest boiling points). This distillation method works on<br />
the principle that boiling occurs when the vapor pressure of a liquid exceeds the<br />
ambient pressure. Vacuum distillation is used with or without heating the solution<br />
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