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Unformatted text preview: Thermodynamics Challenge Problem, Nov. 7-13 Part I. Free energy and the direction of change Consider the now familiar reaction of the vaporization of water. H 2 O (l) H 2 O (g) Table 1 : H f and S values for water. H 2 O (g) H 2 O (l) H f (kJ mol-1 ) -241.8 -285.8 S (J mol-1 K-1 ) 188.8 69.9 1) Calculate H rxn and S from the values in the table above. 2) Using your answers from question 1, a) Fill in the Table 2 below. b) What trends do you notice for H, S, -T S and G? Explain your values. Table 2 : Temperature dependence for the vaporization of water T T (K) H (kJ) S (J/K)-T S (J) G (kJ) 0C 25C 50C 100C 250C 500C 3) What conditions are optimal to make this reaction product favored? High T Low T never favorable always favorable 4) Make a plot of the H, T S and G vs. T using your data in Table 2. 5) At what temperature does the reaction become product favored? Mark this point on your graph and explain your choice. What is significant about this...
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