Question

question 4 of 18 < points possible: 1.00 identify the effect of each error during a thin layer chromatography experiment. the mobile phase used does not move any of the spots at all. choose... the solvent line is not marked after the tlc plate is removed from the chamber. choose... the tlc plate remains in the chamber even after the solvent has reached the top of the plate. choose... pen rather than pencil is used to draw the lines on the plate. choose... accurate rf values cannot be determined. there will be smears on the tlc plate. there can be no separation of components.

Explanation:

1. Using pen instead of pencil can contaminate the TLC plate and its components may move with the solvent, causing smears and inaccurate results. Pencil is inert and won't interfere.
2. If the TLC plate remains in the chamber after the solvent has reached the top, the spots may continue to move and diffuse, making accurate Rf value determination impossible and potentially causing smearing.
3. Not marking the solvent line makes it impossible to accurately measure the distance the solvent front has traveled, which is necessary for calculating Rf values.
4. If the mobile - phase doesn't move any of the spots, it indicates an inappropriate mobile - phase selection for the sample components, resulting in no separation.

Answer:

Using pen rather than pencil: There will be smears on the TLC plate.
The TLC plate remains in the chamber: Accurate Rf values cannot be determined.
The solvent line is not marked: Accurate Rf values cannot be determined.
The mobile phase used does not move any of the spots: There can be no separation of components.