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Calculate the change in enthalpy

  1. Nov 5, 2005 #1
    how do you solve the following problem?

    calculate the change in enthalpy and the change in entropy when 1 mole of SiC is heated from 25 degrees C to 1000 degrees C.
    Cp=50.79+1.97*(10^-3)T-4.92*(10^6)(T^-2)+8.2*(10^8)(T^-3) J/(mole*K)
     
  2. jcsd
  3. Nov 5, 2005 #2

    siddharth

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    The variation of Entropy with temperature for a system is given by
    [tex] S(T_f) = S(T_i) + \int \frac{dq_{rev}}{T} [/tex]
    When the system is under constant pressure and there is no non-expansion work,
    [tex] dq_{rev} = C_p dT [/tex]
     
  4. Nov 6, 2005 #3
    how do you know that the question is under constant pressure?
     
  5. Nov 6, 2005 #4
    because they give u Cp, which is the specific heat at constant pressure
     
  6. Nov 6, 2005 #5
    @@
    how do you know that there's no non-expansion?
     
  7. Nov 6, 2005 #6

    siddharth

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    Non expansion work is work done by the system other than in expansion.
    For example, electrical work. So unless it is specifically stated, there is usually no non-expansion work.
     
  8. Nov 6, 2005 #7
    thank you very much!!!
     
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