CHEM 6AL Q2 MATERIAL EXAM
QUESTIONS AND ANSWERS 100% PASS
2026/2027
TLC - ANS thin layer chromatography
liquid
Thin layer chromatography - ANS a separation technique that involves the separation of small
molecules as they move through a silica gel (polar)
based off polarity
mobile phase - ANS A liquid that is run through the stationary phase in chromatography
(solvent)
solid phase - ANS silica plate (polar)
stationary
polar and nonpolar molecules are bound
What molecules are more attracted to the solid phase - ANS polar molecules
2026/2027 ALLRIGHTS RESERVED
1
, as the mobile phase travels, what happens to the molecules - ANS polar molecules spend
more time interacting with the solid phase while nonpolar spend more time in the solvent
resulting in nonpolar molecules having a faster migration rate
Rf value - ANS distance travelled by solute / distance travelled by solvent
greate Rf = greater migration rate
reverse phase chromatography - ANS The opposite of traditional thin-layer chromatography,
in which the stationary phase is nonpolar (capped silica)
nonpolar migration rate decreases
polar migration rate increases
Why is filter paper included into the beaker when preparing the chamber for TLC - ANS The
purpose of the moistened folded piece of filter paper inside the chamber is so it can saturate
the atmosphere with solvent vapor, preventing the solvent on the plate from evaporating during
development. This will ensure we have accurate Rf values and a fast, consistent separation.
Visualizing TLC - ANS Fluorescent indicator on TLC plate--> visualized using UV light
compound must be "UV-active" --> conjugation is present
Effect of mobile phase polarity - ANS Will affect Rf values
Increasing solvent polarity will increase Rf values as the polar solid phase will choose to interact
with the solvent, allowing both polar and nonpolar molecules to travel further
Decreasing polarity will decrease Rf values
2026/2027 ALLRIGHTS RESERVED
2
QUESTIONS AND ANSWERS 100% PASS
2026/2027
TLC - ANS thin layer chromatography
liquid
Thin layer chromatography - ANS a separation technique that involves the separation of small
molecules as they move through a silica gel (polar)
based off polarity
mobile phase - ANS A liquid that is run through the stationary phase in chromatography
(solvent)
solid phase - ANS silica plate (polar)
stationary
polar and nonpolar molecules are bound
What molecules are more attracted to the solid phase - ANS polar molecules
2026/2027 ALLRIGHTS RESERVED
1
, as the mobile phase travels, what happens to the molecules - ANS polar molecules spend
more time interacting with the solid phase while nonpolar spend more time in the solvent
resulting in nonpolar molecules having a faster migration rate
Rf value - ANS distance travelled by solute / distance travelled by solvent
greate Rf = greater migration rate
reverse phase chromatography - ANS The opposite of traditional thin-layer chromatography,
in which the stationary phase is nonpolar (capped silica)
nonpolar migration rate decreases
polar migration rate increases
Why is filter paper included into the beaker when preparing the chamber for TLC - ANS The
purpose of the moistened folded piece of filter paper inside the chamber is so it can saturate
the atmosphere with solvent vapor, preventing the solvent on the plate from evaporating during
development. This will ensure we have accurate Rf values and a fast, consistent separation.
Visualizing TLC - ANS Fluorescent indicator on TLC plate--> visualized using UV light
compound must be "UV-active" --> conjugation is present
Effect of mobile phase polarity - ANS Will affect Rf values
Increasing solvent polarity will increase Rf values as the polar solid phase will choose to interact
with the solvent, allowing both polar and nonpolar molecules to travel further
Decreasing polarity will decrease Rf values
2026/2027 ALLRIGHTS RESERVED
2
