Calculate the standard enthalpy of the reaction, ΔH∘rxn, for the thermite reaction:

2Al (s) + Fe2O3 (s) →2Fe (s) + Al2O3 (s)

Elements in their standard state have an enthalpy of formation value of zero. The standard enthalpies of formation of Fe2O3 and Al2O3 are

ΔH∘f of Fe2O3 (s) = -825.5 kJ/molΔH∘f of Al2O3 (s) = -1675 kJ/mol

Express your answer to three significant figures and include the appropriate units.

Question

Chemistry

Robert Sanford

22 March, 10:13

Calculate the standard enthalpy of the reaction, ΔH∘rxn, for the thermite reaction:

2Al (s) + Fe2O3 (s) →2Fe (s) + Al2O3 (s)

Elements in their standard state have an enthalpy of formation value of zero. The standard enthalpies of formation of Fe2O3 and Al2O3 are

ΔH∘f of Fe2O3 (s) = -825.5 kJ/molΔH∘f of Al2O3 (s) = -1675 kJ/mol

Express your answer to three significant figures and include the appropriate units.

+5

Answers (1)

Know the Answer?

Beatrice Fernandez · Answer 1

The answer to your question is ΔH rxn = - 849.5 kJ/mol

Explanation:

Reaction

2Al (s) + Fe₂O₃ (s) ⇒ 2Fe (s) + Al₂O₃ (s)

Enthalpy of reaction

ΔHrxn = ∑ H products - ∑ H reactants

ΔHrxn = ∑ (H (Al₂O₃) + H (Fe) - ∑ (H Fe₂O₃ + H Al)

ΔHrxn = [-1675 + 0] - [ - 825.5 + 0]

ΔHrxn = - 1675 + 825.5

ΔHrxn = - 849.5 kJ/mol