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Homework Help: Need help understanding this question

  1. May 13, 2012 #1
    1. The problem statement, all variables and given/known data
    Dry steam is compressed isothermally from a pressure of 1 bar to 4 bar. if the initial volume is 0.5 m^3, calculate the volume of the steam after compression

    2. Relevant equations

    Dont know

    3. The attempt at a solution
  2. jcsd
  3. May 13, 2012 #2


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    it means with the temperature staying constant :wink:

    (from the greek "iso-", meaning "same")
  4. May 13, 2012 #3
    so how do i calculate it , does anyone know the equation of how to do it?
  5. May 13, 2012 #4
    Since this is dry (completely vapor state) you could model with the ideal gas law


    since it is isothermal T is does not change, therefore: n,R, and T are all constant and the right side of the equation is the same before and after compression, so

    V2 = (P1V1)/P2 , plug and chug
  6. May 13, 2012 #5
    do i convert the 1 bar ? or do i just keep it as
    v2=(1x0.5)/4 ?
  7. May 13, 2012 #6


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    Is there anymore information, e.g., the temperature, or the amount of superheat? Using the ideal gas law, or Boyle's law would be appropriate for an approximation. If the temperature is at a saturation level between 1 bar and 4 bar, then at the intermediate pressure, there would be some condensation (vapor to liquid transformation).
  8. May 13, 2012 #7
    no that was all the information that was given
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