The change in enthalpy for the phase transition of N2O4 from liquid to solid cannot be calculated without specific data for N2O4 at -9.4°C, though it is known to be 50.6 kJ/mol at 25°C.
Step-by-step explanation:
The question pertains to the change in enthalpy (ΔH, in kJ mol⁻¹) of the phase transition of dinitrogen tetroxide from liquid to solid form at a non-standard temperature of -9.4°C. Without the specific enthalpy of fusion for N₂O₄(l) -> N₂O₄(s) at -9.4°C being provided, we cannot calculate the exact value. However, at 25°C, the standard enthalpy change is given as 50.6 kJ/mol. To find the enthalpy change at -9.4°C, one would typically use calorimetry data or apply corrections based on heat capacities, provided such data are available.