How do I calculate the Gibbs free energy change for a reaction when given the entropy change, enthalpy change and the reaction conditions>
deltaG= Gibbs free energy
deltaG=deltaH - TdeltaS
If deltaH= 150 kJ/mol and deltaS=2.1 J/mol we must first convert the deltaS into kJ/mol, this is done by multiplying by 10-3 .
So deltaS= 2.1 x 10-3 kJ/mol. If the reaction is done at 25 degrees celcius, we must convert it to Kelvin, by adding 273. This gives 298 K.
So the value of deltaG can be worked out:
deltaG= (150 kJ/mol) - (298) x( 2.1x 10-3)
deltaG= 149. 4 kJ/mol
AM
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