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Homework Help: Dilution of Hydrogen Peroxide

  1. Dec 18, 2014 #1
    < Mentor Note -- thread moved to HH from the technical forums, so no HH Template is shown >

    The experiment I'm trying to do can be found in the attachment below.

    Prepare 20 mL solutions of hydrogen peroxide in the following concentrations: 0%,0.5%, 1.0%, 1.5%,
    2.0%, 2.5%, 3.0% hydrogen peroxide.

    I'm starting with hydrogen peroxide at 3% concentration. How do I to get these concentrations? What measurement tools do you need to do this? I'm not a chemist so I have no idea. Is it dilution?

    Attached Files:

    Last edited by a moderator: Dec 19, 2014
  2. jcsd
  3. Dec 18, 2014 #2


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    These are mass percentages. Properly you add a large enough mass of water to a weighed amount of 3 % solution so that the total mass of hydrogen peroxide divided by the total mass of solution is the percentage you're interested in having.

    For practical purposes, you can consider the density of water and of starting and ending solutions to be one, and use a volumetric flask.
  4. Dec 18, 2014 #3


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    The 0% concentration seems odd. It's just 20 ml of water.
  5. Dec 18, 2014 #4


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    Odd, but not uncommon. Specifically states the obvious point that effects of a particular agent/reagent/compound are compared to situations where no effects are possible. A global specification would be that the solution be 0% {all 20-30M compounds listed in the CAS Registry}.
  6. Dec 19, 2014 #5
    Thank you for your response and willingness to assist me.

    total mass of hydrogen peroxide / total mass of solution = % concentration after dilution

    x / 1 = 0.5%
    x = 0.5%

    total solution = 20 mL

    20 mL - 0.5 = 19.5 mL

    or is it...

    20 mL - 0.005 = 19.995 mL

    How does density fit into all this?
    I know Density = Mass / Volume.
    The density of water is 999.97 kg/m3 = Mass / Volume. Is the mass 20 mL?
    Last edited: Dec 19, 2014
  7. Dec 19, 2014 #6


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    Good one.
  8. Dec 19, 2014 #7
    Thank you for your helpful guidance.
  9. Dec 20, 2014 #8
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