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Someone check my answer please.

  1. May 9, 2012 #1
    Someone check my answer please. :)

    1. The problem statement, all variables and given/known data

    The rate of decomposition of hydrogen peroxide was studied at a particular temperature. H2O2(aq) = H2O (l) + 1/2O2(g)

    The initial concentration of hydrogen
    peroxide was 0.200 mol/L. 10.0 s later,
    it was measured to be 0.196 mol/L.

    b) 0.500 L of hydrogen peroxide solution was
    used for the experiment. What mass was lost
    as O2 bubbled out of solution in this initial
    10.0 s interval?

    3. The attempt at a solution

    What I did was.

    0.500 L * 0.200 mol/L = 0.1

    0.500 L * 0.196 mol/L = 0.098

    0.1 - 0.098 = 0.002mol

    0.002 * 16 = 0.032 g

    What I'm doubting is.

    0.500 L * 0.196 mol/L = 0.098

    Won't the volume change after 10 seconds?
     
  2. jcsd
  3. May 10, 2012 #2

    Borek

    User Avatar

    Staff: Mentor

    Re: Someone check my answer please. :)

    Yes, it will change, no, you don't have to worry - change will be negligible. You are replacing hydrogen peroxide with equimolar amount of water.
     
  4. May 10, 2012 #3
  5. May 10, 2012 #4

    Borek

    User Avatar

    Staff: Mentor

    Re: Someone check my answer please. :)

    Something else makes it completely irrelevant. He started with a 0.2M solution. Using density tables (or concentration calculator) you can easily check initial density to be around 1.0012 g/mL - so even after complete decomposition density change is just around 0.1%.
     
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