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Homework Help: Osmotic Pressure & Mass Percent

  1. Feb 3, 2008 #1
    [SOLVED] Osmotic Pressure & Mass Percent

    A solid mixture of KCL, KNO3, and Ba(NO3)2 is 20.92 mass percent chlorine, and a 1.000g sample of the mixture in 500.0 mL of aqueous solution at 25 C has an osmotic pressure of 744.7 mm Hg. What are the mass percents of KCl, KNO3, and Ba(NO3)2 in the mixture?

    First I started out using osmotic pressure equation after I converted 744.7 mm Hg to atm.

    .9799atm=7x(.08206 L*atm*K[tex]^{-1}[/tex]*mol[tex]^{-1}[/tex])(298K)

    x=.0057 mol of ions/liter (I chose 7x because it appears there would be 7 ions, assuming they'd all dissociate completely)

    Here however is where I'm stuck already. Any advice on where to go from here?
  2. jcsd
  3. Feb 4, 2008 #2


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    From here determine how many moles of ions are in half a liter.
  4. Feb 6, 2008 #3
    I was able to figure it out from here, though it wasn't pretty. I ended up having to make two equations with two different variables. Thanks.
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