In which compounds is the mass fraction of oxygen higher: Al2O3 or CaO?

In this task, it is necessary to determine in which of the following substances the mass fraction of oxygen is greater. We write down the solution.

Determine the mass content of oxygen in aluminum oxide.

First, you need to determine the molar mass of aluminum oxide and oxygen in the compound.

M (Al2O3) = 2 * 27 + 3 * 16 = 101.96 g / mol.

M (O2) = 16 * 3 = 48 g / mol.

W = 48 / 101.96 = 0.47; 47%.

Next, we determine the mass fraction of oxygen in calcium oxide.

M (CaO) = 56 g / mol.

M (O2) = 16 * 1 = 16 g / mol.

W = 16/56 = 0.29; 29%.

Answer: The percentage of oxygen in aluminum oxide is higher.