Answer: 438 K
Explanation:
According to Gibbs equation:
[tex]\Delta G=\Delta H-T\Delta S[/tex]
[tex]\Delta G[/tex] = Gibb's free energy change
[tex]\Delta H[/tex] = enthalpy change = 20.1 kJ/mol = 20100 J/mol
T = temperature
[tex]\Delta S[/tex] = entropy change = 45.9 J/Kmol
A reaction is at equilibrium when [tex]\Delta G[/tex] = Gibb's free energy change is zero and becomes spontaneous when [tex]\Delta G[/tex] = Gibb's free energy change is negative.
[tex]\Delta H=T\Delta S[/tex]
[tex]20100=T\times 45.9J/Kmol[/tex]
T=437.9K
Thus the temperature at which the reaction change from nonspontaneous to spontaneous in the forward direction is 438 K