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Flashcards in Post-Lab Questions Deck (11)
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1
Q

What is the order of polarity of the 3 TLC eluents? (hexane, toluene, and ethyl acetate)

A

least to most 1. hexane 2. toluene 3. ethyl acetate

2
Q

What is the difference between adding NaHCO3 and NaOH to the extraction compound mixture of acetanilide, p-t-butyl phenol, p-toluic acid?

A

NaHCO3 only deprotonates strong acid p-toluic acid so you are able to isolate it. If you used NaOH first, it would deprotonate both t-butyl phenol and p-toluic acid so you couldn’t get crystals

3
Q

What would happen if you removed the plate when the eluent traveled up only half way?

A

the compounds would not be separated properly and an inaccurate Rf value would result.

3
Q

What happens if the TLC plate develops in an unclosed chamber?

A

the compound or eluent may dissolve instead of traveling

4
Q

What was the purpose of the extraction of clove oil and aqueous NaOH?

A

remove impurities by trapping them in the extracted layer

6
Q

What would happen if TBME was used as the only eluent?

A

TBME would be strong enough (polar enough) to move ferrocene and acetylferrocene and I wouldn’t be able to separate the compounds because they would move together

7
Q

What would happen if hexane was used as the only fluent?

A

The acetylferrocene would take a lot of eluent and a long time to be collected.

8
Q

What happens if the eluent level is higher than the level of the origin?

A

the mixture spots would dissolve rather than travel up

9
Q

What is the result of an increase in eluent polarity?

A

It increases the attraction of the compounds to the eluent and therefore they move farther and lead to a larger Rf value

10
Q

What is the difference between adding NaHCO3 and NaOH to the extraction compound mixture of acetanilide, p-t-butyl phenol, p-toluic acid?

A

NaHCO3 only deprotonates strong acid p-toluic acid so you are able to isolate it. If you used NaOH first, it would deprotonate both t-butyl phenol and p-toluic acid so you couldn’t get crystals

11
Q

What was the purpose of the extraction of clove oil and aqueous NaOH?

A

remove impurities by trapping them in the extracted layer