Question

1) A student develops their TLC plate and places it under a UV light, but nothing appears. What mistake might the student have made?

a) Spotted the compound below the level of eluent

b) Spotted the compound above the level of eluent

c) Used a sample that was too concentrated

d) Used too much sample

2)Thin layer chromatography, TLC, is commonly used to monitor reactions to completion. Using this technique, what would indicate to a student that the reaction is complete?

a) One or more of the starting materials is no longer present on the TLC plate.

b) A spot for the product will appear on the TLC plate.

c) The amount of time the procedure called for has passed.

d) The reaction mixture has changed color.

3)In thin-layer chromatography, TLC, analyses, a piece of filter paper is often placed in the developing chamber. Select the function of the filter paper.

a) The filter paper prevents developing solvent evaporation by shading the TLC plate and solvent.

b) The filter paper slowly filters the developing solvent.

c) The filter paper saturates the atmosphere of the chamber with solvent vapors.

d) The filter paper absorbs protons from the developing solvent.

Answer 1

1. correct answer is (a). It is because, he puts the compound below the eluent level; as a result a result the compound gets dissolved in the eluent and not moving in the TLC plate.

2. Actually both options (a) and (b) are correct. As the reaction proceeds, one or more reactants will no longer be present and new spot corresponding to product will form. correct option will be (b) if you have to choose anone.

3. correct answer will be (c). Since the filter paper draws the solvent upward.