TLC Quiz

Question 1

What is the structure of acetone?

Answer 1

Oxygen double bonded to a carbon, which is single bonded to two carbons

Question 2

What is the structure of biphenyl?

Answer 2

Two benzene rings connected by a line (no extra carbon). One double bond is above the line, one is below. Left is above, if it matters.

Question 3

What is the structure of benzophenone?

Answer 3

Two benzene rings connected by an extra carbon, which is double bonded to a oxygen. One double bond is above the line, one is below. Left is above, if it matters.

Question 4

What is the structure of benxhydrol?

Answer 4

Two benzene rings connected by an extra carbon, which bonded to an OH. One double bond is above the line, one is below. Left is above, if it matters.

Question 5

What is the structure of dichloromethane?

Answer 5

CH2Cl2

Question 6

What is the structure of ethyl acetate?

Answer 6

Oxygen double bonded to a carbon, which is single bonded to a carbon and an oxygen. The single bonded oxygen is connected to a chain of two carbons.

Question 7

What is the structure of hexane?

Answer 7

Six carbons, zig-zag line

Question 8

What is the structure of methanol?

Answer 8

CH3OH

Question 9

What is the structure of toluene?

Answer 9

Benzene ring, a CH3 connected to the left of a double bond

Question 10

Describe Rf and its function

Answer 10

Distance from starting line to center of sample/Distance from starting line to final solvent front (d/D). Rf can be used to identify unknown components.

Question 11

How does compound polarity and Rf relate?

Answer 11

Lower the polarity the higher the Rf. The stronger a compound is bound to the adsorbent, the slower it moves up the TLC plate.

Question 12

How does solvent polarity and Rf relate?

Answer 12

In general, the more polar the eluent, the more rapidly a given compound moves, and the higher the Rf. Polar compounds, which are strongly attracted to the absorbent, require polar eluents to attract them away from the adsorbent. Solvent polarity should be arranged so that it spreads compounds across plate.

Question 13

Define visualization

Answer 13

the detection of the sample position on the plate used when the components are not colored

Question 14

Describe UV visualization

Answer 14

In the UV method, a fluorescent dye is present on the plate and the compound spots quench fluorescence and show up as a dark spot on a glowing plate.

Question 15

Describe I2 visualization

Answer 15

In the I2 method, the plate is placed in a container of I2 so that the vapors absorb on the spots and produce purple spots.

Question 16

What are the three major visualization techniques?

Answer 16

UV, I2, visualization reagent