Lab 1: OCHEM | Exam Review | Que & Answ
Chromatography *** defined as a method for the separation of a mixture into its components by distribution between a mobile phase and a stationary phase.
In TLC (thin layer chromatography), the stationary phase is generally a finely divided... *** s...
Lab 1: OCHEM | Exam Review | Que & Answ
Chromatography *** defined as a method for the separation of a mixture into its
components by distribution between a mobile phase and a stationary phase.
In TLC (thin layer chromatography), the stationary phase is generally a finely divided...
*** solid (typically silica gel or alumina)
The mobile phase is generally a... *** liquid
The mixture that scientists want to separate is first applied to the *** stationary phase
(bottom of the TLC plate), in which the mobile phase solvent is allowed to move up TLC
plate by capillarity
-this carries the components of the mixture with it
The rates at which the various components move along the path of the stationary
phase... *** vary; it depends on their solubility in the mobile phase and the strength
with which molecules of the different substances are absorbed on the surface of the
stationary phase particles.
Remember that the interactions between the mobile phase and the stationary phase are
separated by *** solubility, size, charge, etc.
How are TLC plates constructed? *** A slurry of SiO2, is mixed with a binding agent,
and then it is poured onto a uniform surface of glass, aluminum, or plastic then dried.
What is one variable that can affect the amount of crude material through the stationary
phase? *** The thickness of the stationary phase.
How do we prepare the sample? *** We prepare the sample in a convenient volatile
solvent (acetone, dichloromethane are the most common) and then transfer a few drops
of the solution to the plate using a capillary.
When pipetting the solution to the plate, it is important to let the solvent... ***
evaporate from the plate in between touches, until enough material has been deposited
for good results.
-make sure that the diameter of such touches is small
Once the sample has been introduced onto the plate the chromatogram is developed
by.. *** placing it upright in a developing chamber that contains some of the mobile
phase liquid.
The atmosphere of the developing chamber must be kept saturated with... *** the
vapor of the mobile phase in order to get reproducible results.
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