Question

1. At the normal melting point of ice ∆H_fus= 6.007 kJ mol⁻¹ and ∆S_fus= 22.00 J K⁻¹ mol⁻¹.
a) What is ∆G_fusat the normal melting point? Look at your answer. Is it correct? Why or why not?

b) Determine ∆G for freezing water at 1 atm and -10^oC assuming that ∆H_fusand ∆S_fusdo not change much over the 0 → −10^oC temperature range.

c) Determine ∆G for freezing water at 1 atm and -10^oC assuming that ∆H_fusdoes not change much over the 0 → −10^oC range.

Answer 1

a)  

Melting point of ice is T= 273.15K

So

The answer is wrong as should be zero at 273.15K as at that temperature there is an equilibrium between ice and water.

b) At T=273.15-10=263.15K ,

c) Entropy change is given by .

so if the molar specific heat at constant pressure c_p is given then we can find the and thus find as done in part b.