5.4 g of aluminum reacts with oxygen. Find the mass of aluminum of the formed aluminum oxide?

Given:
m (Al) = 5.4 g

To find:
m (Al2O3) -?

1) Write the reaction equation:
4Al + 3O2 => 2Al2O3;
2) Calculate the molar mass of Al:
M (Al) = Ar (Al) = 27 g / mol;
3) Calculate the amount of substance Al:
n (Al) = m (Al) / M (Al) = 5.4 / 27 = 0.2 mol;
4) Determine the amount of substance Al2O3:
n (Al2O3) = n (Al) * 2/4 = 0.2 * 2/4 = 0.1 mol;
5) Calculate the molar mass of Al2O3:
M (Al2O3) = Mr (Al2O3) = Ar (Al) * N (Al) + Ar (O) * N (O) = 27 * 2 + 16 * 3 = 102 g / mol;
6) Calculate the mass of Al2O3:
m (Al2O3) = n (Al2O3) * M (Al2O3) = 0.1 * 102 = 10.2 g.

Answer: The mass of Al2O3 is 10.2 g.