October 29, 2012
CHEM 210 ME01
The process of separating the components of a mixture by distillation into relatively pure fractions is referred to as fractional distillation. Simple distillation, a process with similar goals, is noted for being a satisfactory attempt at separating two components in an ideal mixture, but not as accurate as fractional distillation. To explore these statements further, there needs to be an in depth look at the theory that supports them and the differences in their construction.
The distillation process is a classic technique that is commonly used in chemistry studies to identify and purify organic substances. The physical process of boiling a mixture allows vapors of individual components to be distinguished through their released vapors at their specific boiling points. In theory, when the mixture heats up, the temperature will rise until the lowest boiling point of the substance is reached and then that individual substance will become a vapor, leaving the other substance in the mixture until its boiling point is reached. The result of this process is a hot vapor that passes into a condenser where it is converted to the liquid, which is then collected in a receiver flask.
While this procedure would suffice for simple distillation methods, fractional distillation includes multiple further levels that are take to ensure that the vapor re-liquefying is homozygous in its make-up. Many fractionations are made to occur within a distilling column which provides a large surface area on which many evaporation-condensation cycles can take place. The process requires that a temperature gradient be formed in the column so that as the height up the column increases, the temperature decreases to the right degree for vaporizing condensate as it becomes continually enriched in the lower boiling component. With the addition of a fractioning column full of wire mesh, the surface area inside the column is greatly increased. In order to assure the most accurate separation, there needs to be maximum possible contact between the liquid trickling down and the hot vapor rising to ensure the cyclic process. If you didn't have the packing, the liquid would all be on the sides of the condenser, while most of the vapor would be going up the middle and minimally come into contact with it, as in the case of simple distillation. (Clark 2005)
The purpose of this lab was to test these theories and see if the addition of a long, wire packed fractioning column to a simple distillation set-up would experimentally provide a more accurate separation of the two components making up the mixture as the theories would claim. SAFETY
Mass46.07 g/mol88.15 g/mol
Boiling Point78.4oC 137.5oC
Ethanol and n-pentanol are both chemical substances that require precautions to be taken when being used in lab. Ethanol and n-pentanol are flammable and therefore there needed to be caution taken that the mixture of these substances did not come in to contact with any open flame. This lab did not utilize a Bunsen burner therefore it was easy to ensure that there were not any complications. Ethanol can cause severe irritation if it comes into contact with the eye. For this reason, eye protection was worn at all times throughout the lab. Ethanol can also be dangerous if consumed, causing damage to the liver and kidneys with repeated exposure. There was no ingestion of any of the mixture for this reason. Lastly, ethanol may cause nerve damage with repeated inhalation so there was precaution taken to keep the solution away from breathing range.
N-pentanol can cause skin dryness and scratching with repeated exposure. To avoid this from happening, long sleeves and pants were worn to minimize exposed skin area. Gloves and lab coats were worn to avoid any direct contact when dealing with the mixed solution. If ingested, it...