Make up the chemical formula of the silicon compound with oxygen and determine

Make up the chemical formula of the silicon compound with oxygen and determine the mass fractions of these elements in the resulting oxedone.

Given:
SixOy

To find:
ω (Si in SixOy) -?
ω (O in SixOy) -?

Decision:
1) Since oxygen will exhibit an oxidation state (-2), then silicon, being in group IV, will exhibit an oxidation state (+4);
2) Formula of silicon oxide:
SiO2;
3) Mr (SiO2) = Ar (Si) * N (Si) + Ar (O) * N (O) = 28 * 1 + 16 * 2 = 60;
4) ω (Si in SiO2) = N (Si in SiO2) * Ar (Si) * 100% / Mr (SiO2) = 1 * 28 * 100% / 60 = 46.67%;
5) ω (O in SiO2) = 100% – ω (Si in SiO2) = 100% – 46.67% = 53.33%.

Answer: Mass fraction of Si is 46.67%; O – 53.33%.