Answer Happy

Using NMR to monitor distillation efficiency The most popular method for separating miscible compounds with different boiling points is by simple distillation. The liquid mixture is placed in a round-bottom flask that has been fitted with a distillation head, which is in turn attached to a condenser. The end of the condenser is placed over a collection vessel in which the distillate is collected. As the flask is heated, each liquid will vaporize once its boiling point is reached. The vapor rises through the distillation head and passes into the condenser. The vapor then passes through a water-cooled condenser, which causes it to condense into a liquid and drip into the collection flask. Distillations can be monitored by observing the temperature at the entrance to the condenser; as the apparatus heats up, the vapor from the first component (with the lowest boiling point) will reach the thermometer and enter the condenser while the higher boiling point components condense lower in the apparatus. The temperature will remain constant until all of the first liquid has been removed at which point the temperature will increase and plateau again until the second liquid is distilled away; this pattern will repeat until all liquids have been distilled.
adapter Simple Distillation. thermometer H₂O out cold H₂O in boiling flask receiving vessel heating mantle Figure 1. A distillation apparatus for separating liquids in a mixture. condenser boiling chip
Part I: Answer the following questions related to the theory of distillation. 1. During distillation, which physical property is used to separate compounds in a mixture? This video by professor Dave may be helpful. 2. What is the purpose of the condenser? How does the cold water, around the outer jacket, help with the distillation?
3. What is the purpose of the boiling chip in the boiling flask? 4. In trying to measure the temperature of the boiling mixture, comment on how effective the apparatus will be in containing heat? In other words, do you think the temperature measurements will be higher or lower than expected temperatures, given the apparatus shown in figure 1. 5. During prohibition period, when alcohol was illegal in the US, there was an underground operation of alcohol production and distribution. During this time, in the 1920's, bootleggers would brew spirits such as whiskey and rum then distribute them to local citizens and secret social events. Homemade whiskey is prepared by fermenting a barley/rye mash then extracting the ethanol through a crude distillation apparatus. If the bootleggers weren't careful, methanol would co-extract with the ethanol. Methanol is toxic. In small doses it can cause vomiting and vision impairment, in large doses it can cause death. What would be one suggestion you might have for bootleggers trying to minimize the amount of methanol in their distillate? 6. Distillation is also used in oil refineries to separate different molecular components from the crude oil mixture. These refineries use fractional distillation, to achieve better separation of oil components. What is the purpose of the "plates" in a fractional distillation column? Which condition makes a more desirable, separation, more plates or less plates?