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WorksheetsPhyChem1Ex7
Total questions: 8
Worksheet time: 4mins
The Rf is
the retention factor
a derived number between 0.0 and 1.0
a measurement of the chromatographic behavior of a substance
all of the above
A substance with a low affinity for the stationary phase will have a relatively
low Rf
high Rf
cannot be determined
A substance with a high affinity for the mobile phase will tend to be
high Rf
low Rf
similar in polarity to the stationary phase
Which functional group was formed as the condensation product of the air pollutants and 2,4-DNPH?
hydramine
hydroxone
hydrazine
hydrazone
A substance which traveled half as far from the origin as the solvent front on a TLC plate has an Rf of what?
1.0
0.5
0.0
cannot be determined
In a chromatographic separation, substances should have
similar distributions between the mobile and stationary phases
high affinity for both phases
low affinity for both phases
dissimilar distributions between both phases
The denominator in the Rf calculation is the
distance solvent level moved from origin to end point
solvent front
eluent front
all of the above
If you ran a TLC plate in 20% ethyl acetate in hexanes and measured an Rf of 0.1 for your substance, how would you change the mobile phase to increase the Rf?
Add more of the 20% solvent
Add more ethyl acetate
Add more hexanes
Add more substance
