Establish the molecular formula for the homologue of benzene, the vapor density of which

Establish the molecular formula for the homologue of benzene, the vapor density of which with respect to nitrogen is 3.786.

Given:
Benzene homolog
D N2 (substances) = 3.786

Find:
substance -?

Solution:
1) Aromatic hydrocarbons have the general formula:
CnH2n-6;
2) Calculate the molar mass of nitrogen:
M (N2) = Mr (N2) = Ar (N) * N (N) = 14 * 2 = 28 g / mol;
3) Calculate the molar mass of the substance:
M (CnH2n-6) = D N2 (CnH2n-6) * M (N2) = 3.786 * 28 = 106 g / mol;
4) Determine the relative molecular weight of the substance:
M (CnH2n-6) = Mr (CnH2n-6) = 106;
5) Determine the molecular formula of the substance:
Mr (CnH2n-6) = Ar (C) * N (C) + Ar (H) * N (H);
106 = 12 * n + 1 * (2n-6);
n = 8;
Unknown substance – C8H10.

Answer: Unknown substance – C8H10