1. The presence of liquid flowing back through the fractionating column indicates that the components are effectively separating. The liquid droplets that descend back down the column are composed of the compound with the higher boiling point, which doesn’t reach the required energy to vaporize until its specific boiling point is reached. It is important to make sure that the fractioning isn’t too hot, because in that case the liquid will not be able to flow down the column, due to the motion of the upward moving vapor that will greatly oppose it.
2. It is important to maintain a uniform temperature gradient in a fractioning column to allow more distillations to occur. For example, if the temperature in the column significantly dropped the vapors would condense back down the mixture. A constant temperature also ensures that the lower boiling point compound evaporates without the higher boiling point compound. If temperature was too high all of the components in the mixture would vaporize and no liquid will flow back.
3. Boiling point is related to atmospheric pressure, assuming that this is the atmospheric temperature the vapor would be equal to the atmospheric pressure resulting in 1 atm or 760 mmHg.
4. Boiling point is established when vapor pressure within the liquid is equal to the pressure around the liquid. Therefore, increasing atmospheric pressure would in turn increase the boiling point of a liquid. The liquid would exert a higher vapor pressure, which would counteract the greater atmospheric pressure pushing down on the liquid.
5. It is important to have the cooling water enter the bottom of the condenser and not the top because it is required to immediately cool the vapor that comes from the distillation flask, into a liquid, that is collected in the receiving flask. In the scenario that water was to flow from the top of the condenser it would flow straight out of the bottom and in turn would not have a cooling effect on the inner tube of the condenser. Also, since the water comes from the bottom, it runs through the condenser slower than it would if it were to enter from the top. The act of forcing water up the condenser as opposed to down, allows the water to fill the space evenly.