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PH of solution (not enough infromation?)

  1. Mar 8, 2006 #1
    Both are confusing me. I dont know what information to use (K values)
    I'd really appreciate some help!

    Calculate the concentration of all species present in a 0.25M solution of ethylammonium chloride (C2H5NH3CL)
    (Not sure you if you may need this, but C2H5NH2 has a Kb value of 5.6*10^-4... it is not given in the question, it's in the appendixes of my book, which are used a lot in these problems)

    Calculate the pH of a 0.050M Al(NO3)3 solution. Ka value for Al(H2O)6 3+ is 1.4*10^-5.

    EDIT: hmmm after reading analyzing it a little bit, I think I'm supposed to find the Kb of C2H5NH2 for the first one.. in other words
    And that would lead to the answer being
    [C2H5NH3 +] = 0.25M (% dissociation is insignificant)
    [Cl -] = 0.25M
    [H +] = [C2H5NH2] = 2.1ee-6M
    Does this look right?
    Last edited: Mar 8, 2006
  2. jcsd
  3. Mar 9, 2006 #2


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    Science Advisor
    Homework Helper

    Hi, both of these questions involve setting up an equilibrium constant equation. So you can start by showing us this setup for both problems.
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