Although the actual process also requires water, a simplified equation for rusting (rust is shown as Fe2O3) is 4Fe(s) + 3O2(g) => 2Fe2O3(s) ?Hrxn = -1.65 x 103 kJ How much heat is evolved when 0.100 kg of iron rusts? a. 7.39 kJ b. 7.39 x 102 kJ c. 2.96 x 103 kJ d. 3.38 kJ e. 1.18 x 104 kJ