Use standard free energies of formation to calculate ΔG∘ at 25∘C for each of the following reactions.

N2O4(g)→2NO2(g)

ΔG∘rxn = 2.8 kJ
NH4Cl(s)→HCl(g)+NH3(g)

ΔG∘rxn = 91.2 kJ
3H2(g)+Fe2O3(s)→2Fe(s)+3H2O(g)

ΔG∘rxn = 56.4 kJ
N2(g)+3H2(g)→2NH3(g)

ΔG∘rxn = -32.8 kJ

How do the values of ΔG∘ calculated this way compare to those calculated from ΔH∘ and ΔS∘? Which of the two methods could be used to determine how ΔG∘ changes with temperature? Essay answers are limited to about 500 words (3800 characters maximum, including spaces).