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    Hi,
    Can anyone clear this up, in chromatography when are compounds separated by adsorption and when are they separated by relative solubility? I keep getting them mixed up.
    Many Thanks
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    (Original post by JxxxjoexxxJ)
    Hi,
    Can anyone clear this up, in chromatography when are compounds separated by adsorption and when are they separated by relative solubility? I keep getting them mixed up.
    Many Thanks
    If this is in response to the Chemistry OCR B exam question, I don't think you need to go into that much detail. I just wrote that chromatography is used to separate/ isolate compounds so that the desired one can be tested

    Then for the results, I just said that one is faster than the other on the chromatography paper showing that the sample was impure
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    So the components are separated via adsorption when the stationary phase is solid, and by relative solubility when the stationary phase is liquid. In both cases, the stationary phase is bound to a solid support (i.e. the TLC plate in TLC or the capillary surface tubing in GC). In TLC the stationary phase is always solid (i.e. silica gel coated on sheet of glass/plastic), so the mechanism behind separation is always adsorption. In GC, however, the stationary phase can be either liquid or solid, and depending on the state component molecules will be either separated by adsorption or relative solubility.

    Hope this makes sense... this is the amount of knowledge needed for the OCR spec; don't know if you are doing the same one.
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    (Original post by lolo11)
    So the components are separated via adsorption when the stationary phase is solid, and by relative solubility when the stationary phase is liquid. In both cases, the stationary phase is bound to a solid support (i.e. the TLC plate in TLC or the capillary surface tubing in GC). In TLC the stationary phase is always solid (i.e. silica gel coated on sheet of glass/plastic), so the mechanism behind separation is always adsorption. In GC, however, the stationary phase can be either liquid or solid, and depending on the state component molecules will be either separated by adsorption or relative solubility.

    Hope this makes sense... this is the amount of knowledge needed for the OCR spec; don't know if you are doing the same one.
    THis makes a lot of sense and is exactly what i was after thank you!
 
 
 
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