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### Course: MCAT>Unit 10

Lesson 7: Separations and purifications

# Simple and fractional distillations

Learn how chemicals can be separated and purified through distillation, a process which separates them based on their respective boiling points. By Angela Guerrero. . Created by Angela Guerrero.

## Want to join the conversation?

• If H2O is going in and out of the condenser, how does it not mix with the distilled substance?
• It is going into a separate part of the condenser. The condenser is a tube with two walls, so you have two chambers that are totally separate from each other. The water runs through the outside chamber, cooling the wall of the inside chamber so that your con condense your product.
• Could you help me understand the importance of the vacuum adaptor
(1 vote)
• The vacuum lowers the pressure, making it easier to reach higher boiling points. Boiling occurs when the liquid's vapor pressure is equal to the pressure of the gas above it, so lowering the gas pressure makes it possible to boil liquids at a lower temperature.
• At , how do the "stars" condense the ethanol and water (in the fractionating column)? Do the "stars" have to be cold or something?
• Most of the time the stars that are shown are cold glass beads, and retain their temprature.
• At we learn about the temperature plateau of the mixture due to the phase change of the acetone molecules as they reach their boiling point. How come the temperature of the entire mixture plateaus if the remaining molecules haven't reached their boiling point yet?
(1 vote)
• This is because the energy normally associated with raising the temperature (increasing molecular kinetic energy) goes into breaking the attractive forces between the molecules (a phase change).
This energy is called latent heat energy. For evaporation and condensation, it is the latent heat of vaporisation.
Another way to think of this is to imagine the acetone molecules in the phase change process drawing energy from the other molecules.
• Would the setup for distillation be the exact same thing shown in the video or would it be on a larger scale?
• How can we separate Naphthalene and Ammonium Chloride?
(1 vote)
• Naphthalene is highly insoluble in water while ammonium
chloride is not.
We can add distilled water to the mixture to dissolve the
ammonium chloride and then recover the ammonium
chloride by evaporation; the naphthalene will not
dissolve in water in any substantial quantity, therefore
you can separate naphthalene from ammonium chloride.
• Could someone tell me if a liebig condensor is used in either of these examples?
• It is, Liebig condenser is very similar to simple distillation though, it has a water jacket around it and a thermometer, whereas simple distillation just has a pipe and two tubes connecting it
(1 vote)
• At ,does the filling of the fractional column means that filling it with some substance in along its sides or just pouring it just like that so that it would get mixed with the components that has to be separated out?
(1 vote)
• No, it doesn't have to be along the sides. You need to fill the column with the packaging materials with some air space, of course. This is done so that the more volatile material a.k.a the substance with lower boiling point gets to go out into the flask, while the less volatile matter just remains within the column. Because think about it, if the more volatile substance will pass through the tube while the less volatile material will keep hitting the packaging material, which here is the stars and thus it'll just keep condensing again. The more volatile material will keep hitting the stars too, but they will boil very quickly as opposed to the less volatile substance. In the end, if you want to separate the less volatile substance, which here is water, just let the column cool off for a while after you have completely separated the alcohol and the water will eventually drip down the column into the distilling flask.