Why do we use the enthalpy of fusion when calculating the entropy for the freezing of H2O?

[AndresElizarraras 2A]

Textbook problem 4F.13 asks

"Use data in Table 4C.1 or Appendix 2A to calculate the entropy change for (a) the freezing of
1.00 mol H2O(l) at 0.00 degrees celsius (b) the vaporization of 50.0 g of ethanol, C2H5OH, at 351.5 K."

Why do we use the enthalpy of evaporation when solving for the ice's entropy @ 0 degrees celsius.

Furthermore, in part B why do we neglect the temperature when solving for Q = NCT.

Thank you!

[Chem_Mod]

At constant pressure, heat flow is equal to the change in enthalpy. So, we can say:



In part B, the units of temperature cancel out in the calculation for Q.