Final answer:
The change in enthalpy for the phase transition of methane (CH4) from liquid to gas at -161.48°C is –802.4 kJ mol−1. This value takes into account the standard enthalpies of formation and uses mean bond enthalpies for calculation.
Step-by-step explanation:
The question is asking for the change in enthalpy during the phase change of methane from liquid to gas at -161.48°C. The standard enthalpy change (ΔH°) for phase changes can be found by using the stoichiometric coefficients and the standard enthalpies of formation. The process for finding the enthalpy change involves multiplying the ΔHf° of each substance by its coefficient, summing for products and reactants separately, and then subtracting the sum of reactants from the sum of products.
However, the provided experimental value for the reaction CH4(l) → CH4(g) is –802.4 kJ mol−1. It's important to understand that this value may differ from calculated values due to the use of mean bond enthalpies, which are a mean value and do not account for the specific molecular environment in a particular molecule.