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Homework Help: Pka and Solubility problems

  1. Oct 2, 2007 #1
    The pka of p-nitrophenol is 7.15 while 2,5 dinitrophenol pka is 5.15. Would you expected these two compounds to dissolve in sodium bicarbonate solution. pKA of carbonic acid is 6.37.

    Basically, i believe that p-nitrophenol will dissolve in the sodium bicarbonate solution because the sodium bicarbonate is a much stronger base, while the p-nitropheno is a weaker acid but 2,5 dinitrophenol will not dissolve in sodium bicarbonate solution because it is much more acidic.............I would like to know if i'm right or i'm sort of on the right track and if so, where did i go wrong
  2. jcsd
  3. Oct 3, 2007 #2


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    The stronger the acid the easier it is to deprotonate. The pK1 of carbonic acid only tells you at what pH half of the stuff is deprotonated to HCO3-. Sodium bicarbonate is completely deprotonated to HCO3- and a solution of this will have a pH somewhat higher than it's pK1.
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