In a closed system, it is possible to measure the combination of enthalpy and entropy into a single value, which is called Gibbs free energy, detoned with the letter G. The formula to calcula Gibbs free energy is:
ΔG = ΔH - TΔS
Where:
ΔG = is the gibbs free energy
ΔH = is the change in enthalpy
T = temperature in Kelvin
ΔS = change in entropy
We have as values:
ΔH = 31.0 kJ/mol
T = 294K
ΔS = 93.0 J/molK, we need to convert into kJ, therefore it will be 0.093 kJ/molK
Now we add these values into our formula
ΔG = 31.0 - 294*0.093
ΔG = 3.66 kJ