Question

Calculate the energy if 48.7 g of Al reacts in the following reaction. (Al = 26.98 g/mol)

Fe2O3(s) + 2 Al(s) →Al2O3(s) + 2Fe (s) ∆Hrxn = -852 kJ.

Answer 1

769 kJ

Explanation:

We know that we will need the balanced equation with masses, molar masses, and enthalpies, so let’s gather all the information in one place.

A_r: 26.98

Fe₂O₃ + 2Al ⟶ Al₂O₃ + 2Fe; ΔH_rxn = -852 kJ

Mass/g: 48.7

1. Calculate the moles of Al

Moles of Al = 48.7 × 1/26.98

Moles of Al = 1.805 mol Al

2. Calculate the energy released

The conversion factor is 852 kJ/2 mol Al

Heat = 1.805 × 852/2

Heat = 769 kJ