Calculate the standard Gibbs free energy change of reaction in each of the following using the standard molar values for Gibbs free energy change given here. In each case, comment on whether the reaction is spontaneous or not, under standard conditions.

(Values for G^θin kJ mol^–1: C₃H₈(g) = –23.4,

CO₂(g) = –394.4, Fe₂O₃(s) = –742.2, H₂O(l) = –273.2,

H₂O₂(l) = –120.4, MgO(s) = –569.4, NaCl(s) = –384.2,

NH₄NO₃(s) = –184.0, N₂O(g) = +104.2)

a. 2H₂O₂(l) → 2H₂O(l) + O₂(g)

b. NH₄NO₃(s) → N₂O(g) + 2H₂O(g)

c. 2Mg(s) + O₂(g) → 2MgO(s)

d. C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)

e. 3Mg(s) + Fe₂O₃(s) → 3MgO(s) + 2Fe(s)