To calculate the standard enthalpy change for the fusion of solid sodium chloride at 25C and 1 atm, we need to consider the enthalpy changes for each step of the reaction. However, the given reaction is not a fusion reaction, but rather a decomposition reaction. Fusion refers to the process of a solid turning into a liquid, while the given reaction involves the decomposition of solid sodium chloride into liquid sodium and gaseous chlorine.If you are looking for the standard enthalpy change for the fusion of solid sodium chloride, it is not possible to provide a value as sodium chloride does not undergo fusion at 25C and 1 atm. Sodium chloride has a melting point of 801C, and it would require heating the substance to that temperature for it to undergo fusion.If you are looking for the standard enthalpy change for the given decomposition reaction, we would need additional information such as the standard enthalpies of formation for the reactants and products, as well as any relevant phase change enthalpies.