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August 18, 2010 11:36      9in x 6in     b985-ch05     Elementary Physical Chemistry





                               42                   Elementary Physical Chemistry

                                  b) The gas expands into a vacuum from the same V i to the same V f as
                               in Part (a). Calculate w, q, ∆U, ∆H, ∆S, ∆G.
                                              w = 0 because P ext =0 and thus q =0.

                               The other functions are state functions with the same initial and final states
                               as in Part (a) and so the ∆ values must be the same as in Part (a). In other
                               words,

                                       ∆U =0, ∆H =0, ∆S =5.763 kJ and ∆G = −1.573 kJ.
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