The combustion of 0.5 g of a metal requires 0.231 g of oxygen under normal conditions.

The combustion of 0.5 g of a metal requires 0.231 g of oxygen under normal conditions. What kind of metal is it if its valence is 2?

Let’s find the amount of substance O2.

n = V: Vn.

n = 0.231: 22.4 L / mol = 0.0103 mol.

2Me + O2 = 2MeO.

For 1 mole of O2, there is 2 mole of Me. Substances are in quantitative ratios 1: 2. The amount of substance Me is 2 times more than O2.

n (Me) = 2n (O2) = 0.0103 × 2 = 0.0206 mol.

M (Me) = m: n.

M (Me) = 0.5 g: 0.0206 = 24.27 = 24.3 g / mol.

Metal – magnesium Mg.