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Homework Help: Amphoteric Compounds

  1. Nov 16, 2011 #1
    1. The problem statement, all variables and given/known data

    The Ka of H2PO4 is 6.3 * 10^-8. The Ka of HS is 1.3 * 10^-13. Write a formula for the reaction of these substances and explain your results. Both are amphoteric.

    3. The attempt at a solution

    The formula is:

    H2PO4 + HS <--> HPO4 + H2S

    I figured that the H2PO4 will act more like the acid in this particular situation because it has a higher value of Ka. So, H2PO4 will donate a proton while HS will recieve a proton.

    Is this the correct train of thought?

  2. jcsd
  3. Nov 17, 2011 #2


    User Avatar

    Staff: Mentor

    Yes. Just don't ignore charges - use [noparse]-[/noparse] to get -.
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