Question

Calculate the enthalpy change for the thermite reaction: 2al(s)+fe2o3(s)→2fe(s)+al2o3(s), δh∘rxn=−850 kj when 4.00 mol of al undergoes the reaction with a stoichiometrically equivalent amount of fe2o3.

Answer 1

Given:

Enthalpy change ΔH for the thermite reaction = -850 kJ

Moles of Al involved = 4

To determine:

Reaction enthalpy when 4 moles of Al reacts

Explanation:

The thermite reaction is-

2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s)

When 2 moles of Al react the enthalpy change is -850 kJ

therefore, when 4 moles of Al reacts, the change in enthalpy is-

= 4 moles * (-850) kJ/2 moles = -1700 kJ

Ans: Enthalpy change is -1700 kJ