Theory
Gibbs Energy and Spontaneity:
Enthalpy change and entropy change alone cannot determine the spontaneity of the process, so a new thermodynamic function called as Gibbs energy (G) is introduced.
G = H - TS
ΔG = ΔH – T ΔS
ΔG = +ve, reaction is non-spontaneous
ΔG = -ve, reaction is spontaneous
At equilibrium, ΔG = 0,
ΔH = T ΔS
Third Law of Thermodynamics:
A substance which is perfectly crystalline at absolute zero temperature has an entropy of zero.
Calculating the Standard Entropy Change (ΔSorxn) for a Reaction:
