Unknown A (Module 11A)

The purpose of Module 11A was to test for the presence or absence of a particular set of functional groups through the use of wet chemical tests. In this manner, Unknown A which was a colorless solution, was first tested with 2,4-DNP which after mixing for a few seconds formed a bright yellow precipitate. Although this confirms the presence of either a ketone or aldehyde group, one simple chemical test does not completely specify the presence or absence of other functional groups. Therefore, a second test was made in order to test for the presence of alkyl halides (R-Br or R-I specifically). However, after the addition of alcoholic silver nitrate, AgNO3 (test #2) to a few drops of the unknown, the mixture remained colorless and no precipitate formed. Following this, the third test was performed in
Nevertheless, the similarity of odor to different compounds can be a source of error. For instance, the way humans detect odors is due to the presence of seven different receptors in the olfactory area. When smelling different compounds, some odor chemicals bind with olfactory receptors easily, and other odors need more time to bind with receptors. Therefore, after smelling different compounds one after the other, the receptors can be altered and associate the previous odor with the next one, mixing the smell and making difficult to distinguish correctly the respective odor. For this reason, perfume stores recommend to smell coffee beans between fragrances as a nose-clearing