quiz 2: thin layer chromatography

Question 1

what are the 2 basic things that TLC can tell u

Answer 1

useful for qualitative analysis of organic mixture

1) the number of components in the mixture
2) the identity of some or all of those components provided with the unknown standards

Question 2

in what situations would TLC be useful?

Answer 2

1) when you need to follow the progress of a reaction

2) when you need to check the purity of a sample
-if a sample is not pure, impurities should show up

3)when you are going to do a preparative separation by column chromatography and need to find suitable solvent sys

Question 3

stationary phase

Answer 3

thin layer of silicia (200-250 microns thick)
-polar

Question 4

set up of TLC

Answer 4

solvent at the bottom of tank
piece of paper with dots will be place in
the mobile phase will move up the plate by capillary action

Question 5

general behavior

Answer 5

phase affinity
-sample polarity vs polarity of moving and stationary phase

*more polar will migrate slower than a less polar compound

*least polar will travel faster (further)

Question 6

how to calculate Rf

Answer 6

distance traveled by solvent

small rf=more polar
big rf= less polar