Education Chemistry issues

Discussion in 'General' started by profqwerty, 19 Apr 2007.

  1. profqwerty

    profqwerty What's a Dremel?

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    Hi all,

    I'm not sure there's a section for this topic, so i guess here will do!

    I have tio plan a chemistry practical, and am wondering how the "100-volume" labellingsystem works?

    We have to figure out the concentration of 100-Volume H2O2, but no where says what 100-vol actually means...

    Any help greatly appreciated!

    Thanks,

    Profqwerty
     
    profqwerty, 19 Apr 2007
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  2. woof82

    woof82 What's a Dremel?

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    100vol means it decomposes to make 100times its own volume in gas.
     
    woof82, 19 Apr 2007
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  3. specofdust

    specofdust Banned

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    This isn't my question, but what do you mean "its own volume in gas"? Does that mean that it fills 24 litres at SLC, or that it fills 2400 litres at SLC?
     
    specofdust, 19 Apr 2007
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  4. profqwerty

    profqwerty What's a Dremel?

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    So if you have 10cm3 of this 100 vol liquid, it decomposes to form 1000cm3 of gas?
     
    profqwerty, 19 Apr 2007
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  5. hitman012

    hitman012 Minimodder

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    100vol means that for every 1cm3 that decomposes, 100cm3 of oxygen is liberated. If you're measuring reaction progress using a gas syringe, it's easier that way. To convert it to a normal concentration, remember that 2H2O2 --> 2H2O + O2, i.e. at an x mol dm-3 concentration, 0.5x moles of oxygen are liberated for every dm3 decomposed. From there, you can use the fact that a mole of gas occupies 24dm3 at room temperature and pressure to work out the concentration.

    Is this an A2 chemistry investigation?
     
    hitman012, 20 Apr 2007
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  6. woof82

    woof82 What's a Dremel?

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    There you go, hitman explained it nicely. And yes, they are talking about the A2 chemistry investigation (OCR).
     
    woof82, 20 Apr 2007
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  7. profqwerty

    profqwerty What's a Dremel?

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    woof, It's a past paper now...
    It's a practice practical planning exercise. We have to fully plan two methods of finding out the conc of H2O2. we're given 100-vol as an example.

    I've done tiration with MnO4(-) and the gas syringe one. hopefully nailed it!
     
    profqwerty, 20 Apr 2007
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  8. rigers

    rigers What's a Dremel?

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    Chemistry A2 OCR Practicle

    Can anyone possibly help me, I am trying to work out the concentration of hydrogen peroxide using a gas syringe. The hydrogen peroxide is 100-volume; how can I work out the conectration of H202. Any help would be really appreciated.

    Thank you.
     
    rigers, 2 Apr 2009
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  9. Krikkit

    Krikkit All glory to the hypnotoad! Super Moderator

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    Krikkit, 2 Apr 2009
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  10. rigers

    rigers What's a Dremel?

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    Chemistry A2 OCR Practicle

    Yes I realis that but do I need to dilute my 100-volume hydrogen peroxide with water or not and will this affet my molar calculations because I am thinking of using MnO2 as a catalyst.

    Thank you very much
     
    rigers, 2 Apr 2009
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