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Homework Help: Ideal gases. what fun. please help

  1. Feb 7, 2006 #1
    ideal gases. what fun. please help!!

    i'm having problems getting sensible answers...

    1.
    a cylinder contains 4.62g of hydrogen at 17C and 2.32 x10^6 Pa
    calculate number of moles.

    actual mass/molecular mass= 4.62/2= 2.31
    (relative molecular mass given as 2 in the question...is this right??)

    calculate density of gas.
    density=mass/volume

    volume:
    using pV=nRT
    V=nRT/p
    =2.31x8.31x(17+273) all divided by 2.32x10^6
    =0.00239951...

    density=4.62x10^3 (to make it into kg) divided by 0.00239951...

    gives 1925393.101... kgm^-3
    which seems awfully high.
    i have another question but i'll put it in another thread before my computer crashes and i lose all of this.
     
  2. jcsd
  3. Feb 7, 2006 #2

    Hootenanny

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    Gold Member

    I think you'll find the RMM of Hydrogen is 1.
     
  4. Feb 7, 2006 #3
    4.62g equals .00462kg NOT 4.62*10^3kg

    should fix your answer
     
  5. Feb 8, 2006 #4

    well then either my physics teacher is wrong, or he was thinking of it in terms of H2 molecules. i did wonder when i read it if it was right, but i ended up with the right answer.
     
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