Establish the simplest formula for sulfur oxide in which the mass of sulfur is equal to the mass of oxygen.

Given:
SxOy
m (S in SxOy) = m (O in SxOy)

To find:
SxOy -?

Decision:
1) Let m (SxOy) = 100 g;
2) Calculate the mass of S and O in SxOy:
m (S in SxOy) = m (O in SxOy) = m (SxOy) / 2 = 100/2 = 50 g;
3) Calculate the amount of substance S in SxOy:
n (S in SxOy) = m (S in SxOy) / M (S) = 50/32 = 1.5625 mol;
4) Calculate the amount of substance O in SxOy:
n (O in SxOy) = m (O in SxOy) / M (O) = 50/16 = 3.125 mol;
5) Derive the formula SxOy:
x: y = n (S in SxOy): n (O in SxOy) = 1.5625: 3.125 = 1: 2;
Unknown substance – SO2 – sulfur oxide (IV).

Answer: Unknown substance – SO2 – sulfur oxide (IV).