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Homework Help: TLC Rf order

  1. Dec 5, 2015 #1
    1. The problem statement, all variables and given/known data
    arrange the following eluents in an increasing order of Rf of aspirin

    ethyl acetate, n-hexane, n-butanol, methanol

    2. Relevant equations


    3. The attempt at a solution
    my order is n-hexane < n-butanol < ethyl acetate < methanol
    but the order is wrong.
    i am thinking: aspirin is polar, it will adhere onto the polar stationary phase.
    with the increasing polarity of eluents, the Rf will increase as aspirin will dissolve more in the mobile phase.

    So, whats wrong with my ans?
     
  2. jcsd
  3. Dec 5, 2015 #2

    Ygggdrasil

    User Avatar
    Science Advisor
    2017 Award

    You are correct that you should order the solvents with increasing polarity, but you have incorrectly ordered them by polarity (one hint would be to look up the dielectric constant of the different solvents).
     
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