Why is it not possible to achieve a complete separation of the ethanol from the water in the clarified reaction mixture via simple distillation?
I'm not sure about this because I thought the difference between fractional (what was done) and simple distillation is that fractional distillation is performed to purify mixtures in which the components have close boiling points. However, ethanol has a boiling point of 78.4 degrees Celsius and water has a boiling point of 100 degrees Celsius, which really are not close. Please Help!
Does water vaporize at 78.4C? That is the point, I think, you are collecting vapors and condensing them in distillation. Some water vapor is present at 78C, and it is condensed with the alcohol.
You are correct that simple distillation is typically used to separate compounds with significantly different boiling points, as it relies on the vaporization and condensation of the components in a mixture. However, in the case of ethanol and water, the boiling points are indeed close but not close enough for complete separation through simple distillation alone.
The reason for this is that ethanol and water form an azeotropic mixture, which means they have a tendency to evaporate together in fixed proportions. In the case of ethanol-water mixture, the azeotropic composition is approximately 95.6% ethanol and 4.4% water. When you attempt to distill this mixture, the vapor containing ethanol and water will have a similar composition to the mixture itself, making it difficult to achieve complete separation.
To overcome this, fractional distillation is used. Fractional distillation involves the use of a fractionating column which provides additional surface area for vaporization and condensation, allowing for better separation of the components. The column has different temperature zones, with the temperature decreasing as you move up the column. This allows for repeated vaporization and condensation, enriching the vapor in ethanol as it moves up the column.
In the case of ethanol-water mixture, the mixture will enter the column, and as it vaporizes, the vapor will be richer in ethanol. As the vapor rises, it encounters the cooler section of the column and starts to condense. The condensed liquid, which is now enriched in ethanol, flows back down and is collected separately. This process of repeated vaporization and condensation allows for better separation of ethanol from water compared to simple distillation.
So, to summarize, simple distillation is not sufficient for complete separation of ethanol from water due to the formation of an azeotropic mixture. Fractional distillation, on the other hand, provides improved separation by utilizing a fractionating column that allows for repeated vaporization and condensation, leading to a higher purity separation of the two components.