1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

A Gas Question

Discussion in 'General Chat' started by necroeire, Sep 28, 2006.

  1. necroeire

    necroeire Active Member

    Joined:
    Feb 19, 2004
    Messages:
    1,008
    Likes Received:
    0
    Will a cylinder full of Oxygen weigh the same at 20DegC than at 70DegC?
     
  2. Google AdSense Guest Advertisement



    to hide this advert.
  3. FactionOne

    FactionOne Administrator
    Staff Member Administrator

    Joined:
    May 23, 2004
    Messages:
    3,265
    Likes Received:
    171
    This is probably worth checking as my recollections are hazy; and I guess it depends on exactly what tolerances you need to be working to (as I'm sure there is a "small" effect); but AFAIK the volume of the gas may change (because the density changes with temperature), but it's mass shouldn't (apart from that hair-splitting margin)...

    Regards,

    Rob.
     
  4. TDI-line

    TDI-line Uber Post Whore

    Joined:
    Oct 14, 2004
    Messages:
    9,061
    Likes Received:
    39
    And i thought this was about central heating again.
     
  5. jojo

    jojo Looking for Boost!
    Staff Member Moderator quattro Audi S3

    Joined:
    Sep 4, 2003
    Messages:
    27,385
    Likes Received:
    2,474
    Is this one of those Aeroplane vs Conveyor belt threads?
     
  6. tonedef

    tonedef Member

    Joined:
    Mar 25, 2006
    Messages:
    151
    Likes Received:
    1
    Of course it will, it'll just be harder to carry?
     
  7. TDI-line

    TDI-line Uber Post Whore

    Joined:
    Oct 14, 2004
    Messages:
    9,061
    Likes Received:
    39
    And a little hotter.
     
  8. enda1

    enda1 Member

    Joined:
    Jan 17, 2006
    Messages:
    436
    Likes Received:
    0
    Do you mean a cylinder of compressed oxygen as in a cylinder for an oxyacetelyne torch. If so then the weight will be the same as the mass of the gas has not changed its just that the internal pressure on the cylinder wall will be higher as the the gas at 70C has more energy and as such is at a higher pressure
    This is explained by the compined gas law shown below.

    P1 V1 / T1 = P2 V2 / T2

    P= pressure , V =volume and T =temperature in kelvin
    In this case the volume is constant as the cylinder does not change.
    Solving this we get the Pressure at 70C (343Kelvin) = 1.17 x pressure at 20C(293)
     
  9. necroeire

    necroeire Active Member

    Joined:
    Feb 19, 2004
    Messages:
    1,008
    Likes Received:
    0
    That's what I thought but, I was told by an expert from the gas company I'm building a system for....if the cylinder has 20% liguid O2 and 80% compressed O2 and the temperature increases - reducing the pressure by producing more gas, then there will be less liquid oxygen and more gaseous oxygen thus having a lower weight. The total mass will remain the same but the weight will decrease. I still don't understand this explaination but I'm sure he is right.
     
  10. dummi

    dummi smoking a6

    Joined:
    Mar 25, 2004
    Messages:
    1,210
    Likes Received:
    1
    weight is a function of mass , only thing that will change weight would be a change in gravity.
     
  11. god_thats_quick

    god_thats_quick Numptie of the highest order

    Joined:
    Jun 1, 2004
    Messages:
    2,507
    Likes Received:
    1
    I think I could see his logic if the gas / liquid was changing state, but I don't see how it can between those temps as it's boiling point is -180 degrees and even then I don't think it matters. I think it's mass and therefore weight would be constant all other things staying the same except temp.
     
  12. Geordie Mike

    Geordie Mike Yeee-haw

    Joined:
    Dec 14, 2005
    Messages:
    520
    Likes Received:
    0
    No change, it's a closed system. Nothing gets in, nothing gets out. Phase changes don't alter mass.

    Mike
     

Share This Page