The mass fraction of nitrogen in one of its oxides is 30.4%, the density of this oxide

The mass fraction of nitrogen in one of its oxides is 30.4%, the density of this oxide by air is 3.17. Derive the molecular formula for this oxide.

Solution:

1. The molecular weight of air is 29 g / mol.

2. The relative atomic mass of nitrogen is 14, oxygen is 16.

3. Find the molecular weight of the unknown oxide:

29 * 3.17 = 92 g / mol;

4. Find the molecular weight of nitrogen in the compound:

92 * 0.304 = 28 g / mol;

5. Find the number of nitrogen atoms:

28/14 = 2;

6. Find the molecular weight of oxygen in the compound:

92 – 28 = 64 g / mol;

7. Let’s find the number of oxygen atoms:

64/16 = 4;

Answer: the molecular formula of the oxide is N2O4.