Chapter 5, Problem 118IE

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:

${\text{CH}}_{\text{4}}\left(\text{g}\right)\to \text{C}\left(\text{g}\right)+\text{ 4H}\left(\text{g}\right)$

(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 inΔH^o 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?