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Cards In This Set
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Why is TLC a very effective process for seperation and qualitative analysis of small amount of material?
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It is fast, reproducible, and uses only a small amount of sample
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What is a disadvantage with TLC?
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It cannot be used with volatile compounds
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What are volatile compounds?
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They are comounds which tend to evaporate under ordinary temperature and pressure conditions
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What is this process based upon?
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The relative degree of partition of compounds between the given moving liquid phase and a given stationary phase such as silical gel or alumina
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The degree of adsrobtion of the compound being analyzed on the the solid phase(plastic sheet) depends on?
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It depends on the structure of the compound
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When we add the developing liquid how does it move upwards along the solid phase?
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The liquid moves up the plastic plate by capillary action
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How will the compound spotted on the plate react with the moving liquid phase?
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It is attracted to the moving liquid phase and will move up with up with the liquid phase
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How will the different compounds in the substance move according to the moving liquid?
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Different compounds wull move up to diff. heights depending on their structire
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How does the polarity of substances affect how much they travel on the solid sheet?
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The least polar substances will advance furthur than polar substances
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Why do polar substances not travel as high up as non-polar substances?
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This happens because the liq. phase is less polarthan than the stationart solid phase
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What is the main purpose of TLC?
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TLC can determine the number of compounds in a mixture, indicated by the # of spots on the developed plate
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What else can TLC be used for?
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To see if two compounds are identical or not; based on Rf values(same Rf values means identical compounds)
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Why do you have to line the inside of your developing chamber with a "half moon" shaped filter paper?
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To saturate the chamber with vapours of the developing solvent thus reducing its evaporation from the TLC plate
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How much developing solution should be added to the developing chamber?
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5-8 mls
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What must be done if any of the compounds under investigation are highly polar
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You should add drops of acetic acid into the developing chamber before putting the TLC plate in
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