Please show work. Thank you! 121 Experiment 12: TLC Exp 12: How can a chemist us
ID: 590067 • Letter: P
Question
Please show work. Thank you! 121 Experiment 12: TLC Exp 12: How can a chemist use Thin Layer Chromatography to determine the polarity of a molecule? Problem: A student molecules that contain different functional groups. How can the student use thin layer to aid in this task? taking Organic Chemistry lab is trying to determine the polarity of several chromatography Pre-lab Questions are in the appendix at the end of this manual Student Learning Goals I. Leam how chromatography separates molecules using a stationary phase and mobile phase. 2. Leam how to predict the polarity of a molecule based upon its functional group and hydrogen bonding capacity 3. Leam how to predict the polarity of a molecule based upon its Rf value in solvents with varying Prerequisite Knowledge Chromatography is the collective term for a set of laboratory techniques for the separation of mixtures. Several forms of chromatography exist. Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of glass, plastic, or aluminum foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminum oxide or cellulose. This layer of adsorbent is known as the stationary phase. Our TLC plate is a sheet of aluminum foil coated with silica gel (figure 1). plate after developiag wiw moble phae by eluest plate with sample spet mobile paase sew spots loc ation of 0 orignal spot Figure 1: TLC chamber and platesExplanation / Answer
1. The spot is not applied below the solvent level because it will wash off the TLC plate and there will be no development or separation of components. Applying the spot above the solvent level allows the solvent to move up the plate stationary phase by capillary action and separate the components based on development distance governed by equilibrium distribution.
2. Different components in the original spot have different polarities, will move different distances from the original spot location and show up as separate spots. Solvent should not be allowed to run all the way off the top of the plate to make the measurement of development distances between phases possible.