Question

A sample of Al2O3 decomposed to pure aluminum and oxygen. After decomposition, 29.0 moles of Al were recovered. How many moles of Al2O3 were decomposed?

Answer 1

The decomposition of Al2O3 to form pure aluminum (Al) along with the release of oxygen (O2) gas can be represented by the following chemical reaction:

2Al2O3 → 4Al + 3O2

Based on the reaction stoichiometry:

2 moles of aluminum oxide decomposes to form 4 moles of pure aluminum

Therefore, if 29.0 moles of aluminum is recovered, then the moles of aluminum oxide required will be:

= 29.0 moles Al * 2 moles Al2O3/4 moles Al

= 14.5 moles of Al2O3