Answer:
B. 2 Na(s) + O₂(g) → Na₂O₂(s); ΔG∘f=−451.0 kJ/mol
D. 2 SO(g) + O₂(g) → 2 SO₂(g); ΔG°f=−600.4 kJ/mol
Explanation:
The spontaneity of a reaction is given by the value of the standard Gibbs free energy of the reaction (ΔG°rxn). The more negative is the ΔG°rxn, the more spontaneous is a reaction.
The ΔG°rxn can be calculated using the following expression:
ΔG°rxn = ∑np × ΔG°f(products) − ∑nr × ΔG°f(reactants)
By definition, the standard Gibbs free energy of formation of simple substances in their most stable state is zero. That is why, in the reaction of formation of a compound ΔG°rxn = ΔG°f(product).
<em>Based on the standard free energies of formation, which of the following reactions represent a feasible way to synthesize the product?
</em>
<em> A. N₂(g) + H₂(g) → N₂H₄(g); ΔG°f=159.3 kJ/mol. </em>
<em> </em>Not feasible. ΔG°rxn = ΔG°f(product) > 0.
<em>B. 2 Na(s) + O₂(g) → Na₂O₂(s); ΔG°f=−451.0 kJ/mol</em>
Feasible. ΔG°rxn = ΔG°f(product) < 0.
<em>C. 2 C(s) + 2 H₂(g) → C₂H₄(g); ΔG°f=68.20 kJ/mol</em>
Not feasible. ΔG°rxn = ΔG°f(product) > 0.
<em>D. 2 SO(g) + O₂(g) → 2 SO₂(g); ΔG°f=−600.4 kJ/mol</em>
Feasible. ΔG°rxn = ΔG°f(product) < 0.
