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Topic: Finding Free Energy in Freezing water at 8.6C  (Read 2877 times)

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Offline Strike

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Finding Free Energy in Freezing water at 8.6C
« on: February 02, 2012, 02:28:04 AM »
I'm stuck on one of my practice problems in trying to freeze 94 moles of water at 1 atm and the constant temperature of 8.6 C.

The given information:

delta Hfusion = 6025 J/mol
Cp (ice) = 37.7 J/K mol (Heat capacities at constant pressure for ice and water)
Cp (water, liquid) = 75.3 J/K mol
n = 94
T = 8.6 C or 281.75 K

I got dG = dH - TdS (d = delta) and dS = dqrev / T. My notes show these formulas:



(Apparently at constant pressure, the q is equal to dH during phase change - fusion in this case..)

But no where does the question say this is reversible. Do I still use dH(fusion) and T to find dS and simply plug into the Gibbs formula? I also still don't have dH nor did I even touch the heat capacities.


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