Answer:
ΔG° = 108 kJ, Nonspontaneous.
ΔG° = -158 kJ, Spontaneous.
ΔG° = 105 kJ, Nonspontaneous.
Explanation:
The sponteneity of a reaction depends on the standard Gibbs free energy (ΔG°).
If ΔG° < 0, the reaction is spontaneous.
If ΔG° > 0, the reaction is nonspontaneous.
We can calculate ΔG° using the following expression.
ΔG° = ∑np . ΔG°f(p) - ∑nr . ΔG°f(r)
where,
n: moles
ΔG°f(): standard Gibbs energy of formation
p: products
r: reactants
6 Cl₂(g) + 2 Fe₂O₃(s) → 4 FeCl₃(s) + 3 O₂(g)
ΔG° = 4 mol . ΔG°f(FeCl₃(s)) + 3 mol . ΔG°f(O₂(g)) - 6 mol . ΔG°f(Cl₂(g)) - 2 mol . ΔG°f(Fe₂O₃(s))
ΔG° = 4 mol . (-344 kJ/mol) + 3 mol . 0 - 6 mol . 0 - 2 mol . (-742 kJ/mol)
ΔG° = 108 kJ
ΔG° > 0 so the reaction is nonspontaneous.
SO₂(g) + 2 H₂(g) → S(s) + 2 H₂O(g)
ΔG° = 1 mol . ΔG°f(S(s)) + 2 mol . ΔG°f(H₂O(g)) - 1 mol . ΔG°f(SO₂(g)) - 2 mol . ΔG°f(H₂(g))
ΔG° = 1 mol . 0 + 2 mol . (-229 kJ/mol) - 1 mol . (-300 kJ/mol) - 2 mol . 0
ΔG° = -158 kJ
ΔG° < 0 so the reaction is spontaneous.
NO₂(g) + N₂O(g) → 3 NO(g)
ΔG° = 3 mol . ΔG°f(NO(g)) - 1 mol . ΔG°f(NO₂(g)) - 1 mol . ΔG°f(N₂O(g))
ΔG° = 3 mol . (86.6 kJ/mol) - 1 mol . (51.3 kJ/mol) - 1 mol . (104 kJ/mol)
ΔG° = 105 kJ
ΔG° > 0 so the reaction is nonspontaneous.