Concept explainers
The methane molecule, CH4, has the geometry shown in Figure 2.17. Imagine a hypothetical process in which the methane molecule is "expanded, " by simultaneously extending allfour bonds C-H bonds to infinity. We then have the process:
(a) Compare this process with the reverse of the reaction thatrepresents the standard enthalpy of formation of CH4(g).
(b) Calculate the enthalpy change in each case. Which is themore endothermic process? What accounts for the difference inΔHo values? (c) Suppose that 3.45 g CH4(g) reacts with1.22 g F2(g), forming CH4(g) and HF(g) as sole products. What is the limiting reagent in this reaction? If reaction occurs at constant pressure, What amount of heat is evolved?
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