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.