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Postby Palmquist_Sierra_2N » Sat Feb 11, 2017 9:05 pm

Suppose that 50 g of H2O(l) at 20 degrees C is mixed with 65 g of H2O(l) at 50 degrees C at a constant pressure in a thermally insulated vessel. Calculate delta S and delta S total for the process.
Please help explain the set up and solving of this problem. Thanks!

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Re: 9.43

Postby Chem_Mod » Sun Feb 12, 2017 6:05 am

Since you have the initial temperatures and the initial moles (grams *molecular weight of water) of the two bodies, and you know that the vessel is thermally isolated, we know that delta q is equal to 0. Therefore,

and you can plug in the respective values for and using , always using the temperature given as the initial temperature and then solving for the final temperature. Then you're going to want to find an equation that relates temperatures to change in entropy. See if you can solve from there.

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