A piece of filter paper is placed in the TLC developing chamber to: Choose one: provide a lining for the TLC plate to rest on. help the chamber saturate with the developing solvent's vapor. make it easier to visualize the solvent front level. protect the TLC plate.

A sample is run on a TLC plate and gives a single spot as shown below on the left. However, the solvent was not allowed to run up the plate very far, and so the experiment was repeated with a much larger solvent distance as shown on the right below. What would be the approximate Rf value of the spot for the repeat experiment on the right? solvent line solvent line start line start line 01.0 0.9 © 0.5 0.1

complete the table  Procedure Preheat the hotplate stirrer with an aluminum block to 45–50 °C (do not exceed 55 °C). To a clean 5-mL conical vial equipped with a Teflon-coated magnetic stir vane, add 4- bromo-nitrobenzene (152 mg, 0.750 mmol, 1 equiv) and THF (150 μL). Cap the vial and stir the mixture at 45–50 °C for about 30 s to partially dissolve the substrate; don’t stir too fast to avoid splashing the contents on the walls of the vial. Add ammonium chloride (120 mg, 2.2 mmol, 3 equiv), carbonyl iron powder (CIP; 210 mg, 3.80 mmol, 5 equiv), the solution of TPGS-750-M (2% in water, 1.5 mL), and 1 drop of concentrated HCl. Cap the vial and place it on the hot plate stirrer, stirring at 45–50 °C. While the reaction mixture is stirring, prepare an approximate 2% solution of the reactant in DCM (1 sample per 3–4 students) by dissolving 10–15 mg of 4-bromo-nitrobenzene in 0.5 mL of methylene chloride. Prepare the solvent mixture for the mobile phase (25% ethyl…

As solvent polarity increases, the Retention Factor (Rf) of compounds on the TLC plate increases. Group of answer choices True False