To calculate the standard enthalpy change H for the phase transition of solid copper to liquid copper, we can use the given molar heat of fusion Hfus and the number of moles of copper involved in the process. Since we are not given a specific amount of copper, we can calculate the enthalpy change per mole of copper.The molar heat of fusion Hfus is the amount of energy required to convert 1 mole of a substance from its solid phase to its liquid phase at its melting point. In this case, the molar heat of fusion of copper is given as 13.1 kJ/mol.Since we are calculating the standard enthalpy change for the phase transition of solid copper to liquid copper, we can simply use the given molar heat of fusion value:H = HfusH = 13.1 kJ/molThe standard enthalpy change for the phase transition of solid copper to liquid copper is 13.1 kJ/mol.