The conversion of natural gas, which is mostly methane, into products that contain two

Chapter 19, Problem 19.94

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The conversion of natural gas, which is mostly methane, into products that contain two or more carbon atoms, such as ethane (C2H6), is a very important industrial chemical process. In principle, methane can be converted into ethane and hydrogen: 2 CH4{g) ---> C2H6{g) + H2{g) In practice, this reaction is carried out in the presence of oxygen: 2 CH4{g) + Oz{g) ---> C2H6{g) + H20{g) (a) Using the data in Appendix C. calculate K for these reactions at 25 c and 500 c. (b) Is the difference in flG for the two reactions due primarily to the enthalpy term {llH) or the entropy term (-T llS)? (c) Explain how the preceding reactions are an example of driving a nonspontaneous reaction, as discussed in the "Chemistry and Life" box in Section 19.7. (d) The reaction of CH4 and 02 to form CzH6 and H20 must be carried out carefully to avoid a competing reaction. What is the most likely competing reaction?