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Homework Help: Thermodynamics processes

  1. Apr 11, 2010 #1
    1. The problem statement, all variables and given/known data

    Three moles of an ideal monoatomic gas trebles its initial volume in an isobaric expansion from state A to state B. The gas is then cooled isochorically to state C and finally compressed isothermally until it returns to state A. The molar gas constant is R = 8.314 J mol–1 K–1 and Boltzmann's constant is 1.38 × 10–23 J K–1.

    (a) If state B corresponds to a pressure P = 5 atm (1 atm = 1.013 × 10^5 Pa) and temperature T = 535 °C, determine the temperature of the gas in state A.




    2. Relevant equations
    unknown


    3. The attempt at a solution
    the answer to this solution is 269K...and i have NO idea what so ever how to do this, could you please help?
     
  2. jcsd
  3. Apr 11, 2010 #2

    Andrew Mason

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    First, determine the volume at B and then the pressure at C. (Hint: use ideal gas law. Be careful about temp. scale). With that, you can determine the temperature at C, which is the same as the temperature at A.

    AM
     
  4. Apr 12, 2010 #3
    First, determine the volume at B and then the pressure at C. (Hint: use ideal gas law. Be careful about temp. scale). With that, you can determine the temperature at C, which is the same as the temperature at A.

    AM

    hi um i tried to do it as u advised, but i was not able to get the right answer, could you please state the suggested formulas to use in order? thanks
     
  5. Apr 12, 2010 #4

    Andrew Mason

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    Find the volume at B and the temperature at A (which is the same as temperature at C).:

    PV=nRT.

    At B: P = 5 atm = 5 x 101.3 KPa = 506.5 KPa; T = 535+273 = 808K. n = 3 moles

    V = nRT/P = ________?

    This is 3 times the volume at A, so the volume at A is _______. Applying the ideal gas law, the temperature at A is: _______



    AM
     
  6. Apr 14, 2010 #5
    thx alot for ur help!! really appreciate it=]
     
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