# In one of the sulfur oxides, the mass fraction of oxygen is 50%. Determine which oxide it is.

Short solution.

1. If the mass fraction of oxygen in sulfur oxide is 50%, then the mass fraction of sulfur will also

50 %.

100% – 50% = 50%.

2. Find the ratio of the elements in the oxide formula.

We divide the mass fraction of each element by its atomic mass, then we find the ratio of numbers.

S: O = (50: 32): (50: 16) = 3: 1.

The formula for sulfur oxide (VI) is SO3.

Complete solution.

Let’s take the mass of the compound as 100 g.

Let’s find the mass of oxygen.

100 g – 100%,

m- 50%.

m = (100 g x 50 g): 100%,

m = 50 g.

The mass of oxygen is 50 g.

100 g – 50 g = 50 g.

Let’s find the number of substances of oxygen and sulfur atoms.

n = m: M.

n (O) = 50 g: 16 g / mol = 3 mol.

n (S) = 50 g: 32 g / mol = 1 mol.

We find the ratio of the amounts of the substance.

n (S): n (O) = 1: 3.

SO3 oxide formula.