Question

An intimate mix of ferric oxide and Al is used as solid rocket fuel. Calculate the fuel value per gm and fuel value per CC of the mix. Enthalpy of formation & densities are: 

ΔH°_f (Al₂O₃) = -399k cal/mole;

ΔH°_f (Fe₂O₃) = -399k cal/mole;

Density of Fe₂O₃ = 5.2 g/cc; density of Al = 2.7 g/cc.

Answer 1

2Al+ 3/2 O₂ → Al₂ O₃

2Fe + 3/2 O₂ → Fe₂ O₃

Fe₂O₃ + 2Al → Al₂ O₃ + 2Fe 

Mole mix mass 2 mole of Al = 54 (g)