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Derive the density of an ideal gas as a function of temperature?

  1. Jan 6, 2013 #1
    derive the density of an ideal gas as a function of temperature??

    1. The problem statement, all variables and given/known data
    Derive the density of an ideal gas when it is allowed to expand as a function of temperature when pressure is kept constant/


    2. Relevant equations



    3. The attempt at a solution
    density= PM/(RT) , where M is the molecular weight
    or ∂ρ/∂T =M/(RT)
    or ρ(V,P),then keep P constant, ∂ρ/∂V =∂<PM/(RT)>

    actually i am not sure what the question asking about . Thank you
     
  2. jcsd
  3. Jan 7, 2013 #2

    Andrew Mason

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    Re: derive the density of an ideal gas as a function of temperature??

    Relate the mass of the gas to the volume using the ideal gas equation. Use n = m/M where m is the mass of the gas and M is the molecular weight or mass/mole of the gas.

    What is n/V? How is n/V related to density of the gas?

    AM
     
  4. Jan 8, 2013 #3
    Re: derive the density of an ideal gas as a function of temperature??

    m/V is density of gas system
    n /V is density of gas molecule?
    I don't know how to relate.
     
  5. Jan 8, 2013 #4

    Andrew Mason

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    Re: derive the density of an ideal gas as a function of temperature??

    .... and since m = nM...... the density of the gas is ... (in terms of M, P, R and T).

    AM
     
  6. Jan 8, 2013 #5
    Re: derive the density of an ideal gas as a function of temperature??

    So the question want density in terms of P M R T? Then why does the question say when it expand?
     
  7. Jan 8, 2013 #6

    Andrew Mason

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    Re: derive the density of an ideal gas as a function of temperature??

    You should ask the person who drafted the question....it was probably asked this way to just give it some context. What the question is asking is the relationship between T and m/V with constant P. Whether it is expanding or being compressed at constant P makes no difference to the relationship.

    AM
     
  8. Jan 8, 2013 #7
    Re: derive the density of an ideal gas as a function of temperature??

    Thank you.
     
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