Answer to Question #205195 in Molecular Physics | Thermodynamics for Ankush

Question

When iron rusts in air, the following reaction occurs. What is the heat of formation of Iron(III) oxide?

4Fe(s)+3O2(g)=2Fe2O3(s) Delta H= -1643 KJ

Answer 1

The reaction of formation of 1 mole of Fe₂O₃ is following:

2Fe(s) + 1.5O₂(g) --> Fe₂O₃(s)

If $\Delta{H}$ of formation of 2 moles of Fe₂O₃ is -1643 kJ, for 1 mole it will be equal to$\frac{-1643kJ}{2}=-821.5kJ$

Answer: -821.5 kJ/mol