Calculate the mass of aluminum oxide, which is formed by complete combustion in a stream of oxygen

Calculate the mass of aluminum oxide, which is formed by complete combustion in a stream of oxygen of pure aluminum weighing 4.05 g.

1. Let us compose the reaction equation reflecting the combustion of aluminum in oxygen:
4Al + 3O2 = 2Al2O3.
2. Let’s calculate the chemical amount of aluminum:
n (Al) = m (Al): M (Al) = 4.05: 27 = 0.15 mol.
3. Determine the amount of the obtained oxide:
n (Al2O3) = n (Al): 2 = 0.15: 2 = 0.075 mol.
4. Let’s calculate the mass of aluminum oxide:
m (Al2O3) = n (Al2O3) * M (Al2O3);
M (Al2O3) = 2 * 27 + 3 * 16 = 102 g / mol;
m (Al2O3) = 0.075 * 102 = 7.65 g.
Answer: 7.65 g.