Determine the mass fraction of oxygen in the higher oxide of the element located in the fifth subgroup

Determine the mass fraction of oxygen in the higher oxide of the element located in the fifth subgroup (main subgroup) and the 5th period of the Mendeleev system of chemical elements.

Fifth group, main subgroup, 5th period – element Sb – antimony. The formula of the highest oxide Sb2O5. To determine the mass fraction of oxygen in an oxide, you need to multiply the atomic mass of oxygen by the number of oxygen atoms and divide it all by the molar mass of the oxide. M (Sb2O5) = 2 * 121.75 + 5 * 16 = 323.5. W (O) = 5 * 16 / 323.5 = 0.247 (24.7%).