From the data recorded in your laboratory notebook, draw what a ...

[moongchi]

From the data recorded in your laboratory notebook, draw what a TLC plate would look like if it were spotted with the three compounds shown below in different lanes and developed in 90 hexane:10 ethyl acetate. Next to this plate, draw another plate that was spotted with the same three compounds at identical starting points that was developed in 100 hexane to the same distance from the spotting line as the first plate.

Question 2

Two students analyzed the same spice by TLC. One of the students used hexane to extract the essential oil while the other student used diethyl ether. Would you expect their developed TLC plates to look the same if they used the same developing solvent? Explain your answer.

[tennis14576]

Answer to Question 1

The compounds will not move as far on the second plate as they did on the first plate. That is, the Rf's will decrease on the second plate compared with the first plate.

Answer to Question 2

You would expect the plates to look different because the solvents used to extract the compounds were different. Ether would extract out additional polar compounds that hexane would not. The argument that the plates would be different because the polarity of the two extracting solvents would affect how these compounds ran on a TLC plate is incorrect. The extraction solvents would have evaporated off the plate before it was put in the developing chamber.

[moongchi]

Both answers were spot on, thank you once again

[tennis14576]

Great! Please up vote