Can you help me with this enthalpy problem?

Question

The overall reaction in a commercial heat pack can be represented as shown below.

4 Fe(s) + 3 O₂(g)  2 Fe₂O₃(s)      ΔH = -1652 kJ

(a) How much heat is released when 3.56 mol iron is reacted with excess O₂?

(b) How much heat is released when 1.20 mol Fe₂O₃ is produced?

(c) How much heat is released when 1.38 g iron is reacted with excess O₂?

(d) How much heat is released when 13.0 g Fe and 1.57 g O₂ are reacted?

Answer 1

4 Fe(s) + 3 O₂(g) ==> 2 Fe₂O₃(s)      ΔH = -1652 kJ

(a), 3.56 mol Fe x -1652 kJ / 4 mols Fe = -1470 kJ

(b). 1.20 mol Fe2O3 x -1652 kJ / 2 mol Fe2O3 = -991 kJ

(c). 1.38 g Fe x 1 mol Fe / 55,85 g x -1652 kJ / 4 mols Fe = -10.2 kJ

(d). Find which one is limiting. You can do this by dividing moles of each by the corresponding coefficient in the balanced equation.

For Fe: 13.0 g Fe x 1 mol Fe / 55.85 g = 0.233 mols Fe (÷4->0.058)

For O₂: 1.57 g O2 x 1 mol O2 / 32 g = 0.049 mols O2 (÷3->0.016)

O₂ is limiting since 0.016 is less than 0.058.

0.049 mols O₂ x -1652 kJ / 3 mols O₂ = -27.0 kJ