Consider the reaction N2(g) + 202(g) -2NO2(g) Using the standard thermodynamic data in the tables linked above, calculate AGn for this reaction at 298.15K if the pressure of each gas is 47.35 mm Hg. ANSWER: kJ/mol

For the reaction NO(g)+NO2(g)N2O3(g) , use tabulated thermodynamic data to calculate H and S. Then use those values to answer the following questions. (a) Is this reaction spontaneous at 25°C? Explain your answer. (b) If the reaction is not spontaneous at 25°C, will it become spontaneous at higher temperatures or lower temperatures? (c) To show that your prediction is accurate, choose a temperature that corresponds to your prediction in part (b) and calculate G . (Assume that both enthalpy and entropy are independent of temperature.)

Methane can be produced from CO and H2.The process might be done in two steps, as shown below, with each step carried out in a separate reaction vessel within the production plant. Reaction 1 CO(g)+2H2(g)CH3OH(l) S = -532 J/K Reaction 2 CH3OH(l)CH4(g)+12O2(g) S= +162 J/K NOTE: You should be able to work this problem without using any additional tabulated data. (a) Calculate H for reaction 1. (b) Calculate Gf for CO(g). (c) Calculate S° for O2(g). (d) At what temperatures is reaction 1 spontaneous? (e) Suggest a reason why these two steps would need to be carried out separately. Substance Hf (kJ mol-1) Gf (kJ mol-1) S (J mol-1 K-1) CO(s) -110.5 197.674 CH3OH( l ) -238.7 -166.4 126.8 CH4(g) -74.8 186.2

The reaction shown below is involved in the refining of iron. (The table that follows provides all of the thermodynamic data you should need for this problem.) 2Fe2O3(s)+3C(s,graphite)4Fe(s)+3CO2(g) (a) Find H for the reaction. (b) S for the reaction above is 557.98 J/K. Find S° for Fe2O3(s). (c) Calculate G for the reaction at the standard temperature of 298 K. (There are two ways that you could do this.) (d) At what temperatures would this reaction be spontaneous? Compound Hf (kJ mol-1) S° (kJ mol-1) Gf (J mol-1 K-1) Fe2O3(s) -824.2 ? -742.2 C(s, graphite) 0 5.740 0 Fe(s) 0 27.3 0 CO2(g) -393.5 213.6 -394.4.83