The thermite reaction, in which powdered aluminum reacts with iron oxide, is highly exothermic: 2al(s) + fe2o3(s)→al2o3(s) + 2fe(s) use standard enthalpies of formation to find δh∘rxn for the thermite reaction. express the heat of the reaction in kilojoules to four significant figures.

Answer is: heat of the reaction is -851,500 kJ.
Chemical reaction: 2Al + Fe₂O₃ → Al₂O₃ + 2Fe.
ΔHf(Fe₂O₃) = -824,2 kJ/mol; enthalpy of formation.
ΔHf(Al₂O₃) = -1675,7 kJ/mol.
By definition ΔH(element) = 0 kJ/mol.
ΔHrxn = ∑ΔH(products) - ∑ΔH(reactants).
ΔHrxn = 1 mol · (-1675,7 kJ/mol) - 1 mol · (-824,2 kJ/mol).
ΔHrxn = -851,500 kJ.