# The molar mass of the nitrogen compound with hydrogen is 32 g / mol, and the mass fraction of nitrogen atoms in it is 87.5%

**The molar mass of the nitrogen compound with hydrogen is 32 g / mol, and the mass fraction of nitrogen atoms in it is 87.5%. Determine the molecular formula of a substance**

Decision:

Ar (H) = 1 g / mol;

Ar (N) = 14 g / mol.

We determine the mass of the nitrogen element in 32 g of the substance from the proportion, we get:

32: 100 = x: 87.5;

x = (32. 87.5) / 100 = 28 g.

m (N) = 28 g.

Then

m (H) = 32 – 28 = 4 g.

We denote the index of the nitrogen atom by x, and the index of hydrogen atoms by y in the substance’s molecule, we obtain the formula of the substance:

the oxide formula can be represented as follows: NxHy.

We find the indices of atoms in the NxHy molecule

You can write it like this:

x: y = m (N) / Ar (N): m (H) / Ar (H) = 28/14: 4/1 = 2: 4.

Substitute the values of the indices in the formula, we get:

NxHy = N2H4, this is hydrazine