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Homework Help: HELP concentrations of ions

  1. Mar 29, 2010 #1
    HELP!!! concentrations of ions

    1. The problem statement, all variables and given/known data
    Determine the concentration for the following ions:
    H2PO4-
    HPO4^2-
    PO4^3- in the dissociated of 7.0M H3PO4 solution


    2. Relevant equations
    I know that the number given is a phosphoric acid and is a triprotic acid.
    Concentration of atoms example are Na2CO3 (s) → 2 Na+(aq)+ CO32-(aq)
    [Na+] = 2 × [Na2CO3] = 2 × 0.20 M = 0.40 M
    [CO32-] = 1 × [Na2CO3] = 1 × 0.20 M = 0.20 M


    3. The attempt at a solution
    so is it H2PO4-(aq) + H2O(l) = H30(aq) + H2PO4^2-(aq)
    [H2PO4-]= 1 x [H2PO4-] = 1 x 7.0 = 7M then do the same thing for the two instead of 1 do 2 and 3 respectively next.
     
  2. jcsd
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