A 25.0 g sample of a pure solid begins to melt at 78 °C while being heated by an electric element that supplies energy at a constant rate of 120 W. The plateau on the heating curve corresponding to melting lasts exactly 85 s. Calculate the molar enthalpy of fusion, ΔHfus, of the substance in kJ mol⁻¹. (Molar mass = 62.0 g mol⁻¹)