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Homework Help: Entropy change for isobaric heating

  1. Mar 7, 2010 #1
    Hi guys, is this right?

    1. The problem statement, all variables and given/known data
    A mole of nitrogen is heated at constant external pressure of 1 atm from 25° C to 100° C. The heat capacity of nitrogen is 29.1 J/mol·K.

    Calculate ΔSsurr

    2. The attempt at a solution
    delta_S=Q/T = -1*29.1*75/373=-5.85 J/K

    (heat transferred to the system divided by T_surr which we assume to be equal to T_final)

    The solution in my lecture notes says -22 J/K, I can't see where that came from.
  2. jcsd
  3. Mar 7, 2010 #2


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    Homework Helper

    even if they heat it "infinitely slow", it only goes up to about 6½ J/K ,
    no-where near 22 J/K .
    { they must've divided by 100 degrees C by mistake , rather than 373 K }
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