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Homework Help: Calculate the Gibb’s energy of the vaporization of 1 kg of water at 50° C and 1 bar.

  1. Mar 14, 2010 #1
    1. The problem statement, all variables and given/known data
    Calculate the Gibb’s energy of the vaporization of 1 kg of water at 50° C and 1 bar. The enthalpy change for the vaporization of water at its normal boiling point is 2257 J/g, and the heat capacities of liquid and vapour water are 4.18 J/g·K and 2.09J/g·K respectively. What does the answer tell you?


    2. Relevant equations
    delta_G=delta_H-Tdelta_S
    delta_S=Q/T



    3. The attempt at a solution
    The answer is given as 519.2 kJ.

    I assume that the delta_H value to be used in the equation is the one given. But I don't know how to get delta_S. I thought it could be 323*(2257/373) but that yield's the wrong answer. I can't see why the heat capacities have anything to do with it as we are talking about an isothermal process.

    Thanks.
     
  2. jcsd
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