Tlc Sheet Discussion Lab Report

There can be both advantages and disadvantages in using a TLC sheet of a different length. For example, it becomes a disadvantage if the TLC sheet in this lab was 5 cm shorter. If this were the case, then (Sample A) would not have shown up or the second spot of unknown substance #3. Moreover, the unknown substance, which consists of (Sample A, would be incorrectly identified as a pure substance and/or as consisting of only (Sample D). Contrary to using a shorter TLC sheet, a longer TLC sheet might allow more substances of each of the compounds to show up, if they exist. Namely, more information on each compound could be discovered on whether it is a pure compound or if it consists of different substances of greater retention factors that the original length of the TLC sheet did not allow us to see.
Hence, from least to greatest relative polarity, the order of the compounds are as such: ibuprofen, aspirin, acetaminophen, caffeine. According to their molecular structures, caffeine is the most polar because of the unpaired electrons on the nitrogens and the unpaired electrons on the oxygens. In other words, one side of the molecule has two amides and is more negatively charged due to the lone pairs of electrons on the two nitrogens and the two oxygen (6 pairs of lone electrons), while the other side has 1 amine and is less negatively charged. On the other hand, aspirin is only slightly polar in comparison to the other compounds. This is because it has an ester group and carboxylic acid group; however, only the oxygen in the carboxylic acid has lone pairs of electrons that can form bonds. Overall, the differences in their polarities all of these pure compounds is the lone pairs of electrons that have the ability to interact more with other polar