Question

Calculate ΔG∘ for the following reactions. Indicate whether each reaction is spontaneous under standard conditions.

(A) 2SO2 (g) + O2 (g) ---> 2SO3 (g)

(B) NO2 (g) + N2O (g) ---> 3NO (g)

(C) 6Cl2 (g) + 2Fe2O3 (s) ---> 4FeCl3 (s) + 3O2 (g)

(D) SO2 (g) + 2H2(g) ---> S (s) + 2H2O (g)

Answer 1

(A) dG^o = dG^o(products) - dG^o(reactants)

= (2 x -370.4) - [(2 x -300.13) + 0]

= -140.54 kJ/mol

The reaction is spontaneous

(B) dG^o = dG^o(products) - dG^o(reactants)

= (3 x 87.6) - (51.3 + 104.18)

= 107.32 kJ/mol

The reaction is not spontaneous.

(C) dG^o = dG^o(products) - dG^o(reactants)

= (4 x -334.05 + 3 x 0) - (6 x 0 + 2 x -742.24)

= 148.28 kJ/mol

The reaction is not spontaneous

(D) dG^o = dG^o(products) - dG^o(reactants)

= (0 + 2 x -228.61) - (-300.13 + 2 x 0)

= -157.09 kJ/mol

The reaction is spontaneous