Explanation:
According the equation of Gibb's free energy -
∆G = ∆H -T∆S
∆G = is the change in gibb's free energy
∆H = is the change in enthalpy
T = temperature
∆S = is the change in entropy .
And , the sign of the ΔG , determines whether the reaction is Spontaneous or non Spontaneous or at equilibrium ,
i.e. ,
if
• ΔG < 0 , the reaction is Spontaneous
• ΔG > 0 , the reaction is non Spontaneous
• ΔG = 0 , the reaction is at equilibrium
a.
N₂(g) + H₂(g) → N₂H₄ (g) ; ΔG⁰f = 159.3 kJ/mol
ΔG > 0 , the reaction is non Spontaneous , the reaction is not feasible in the forward direction
b.
2Na(s) + O₂(g) → Na₂O₂ (s) ; ΔG⁰ f = − 447.7kJ/mol
ΔG < 0 , the reaction is Spontaneous , the reaction is feasible in the forward direction .
c.
C(s) + 2S(s) → CS₂ (g) ; ΔG⁰f = 67.1 kJ/mol
ΔG > 0 , the reaction is non Spontaneous , the reaction is not feasible in the forward direction
d.
Ca(s) + 12 O₂ (g) → CaO (s) ; ΔG⁰f = −604.0 kJ/mol
ΔG < 0 , the reaction is Spontaneous , the reaction is feasible in the forward direction .
