Set the molecular formula of diene relative vapor density in air 1.862

Given:
Dien
D air. (substances) = 1.862

Find:
substance -?

Solution:
1) Alkadienes have the general formula:
CnH2n-2;
2) Calculate the molar mass of the substance:
M (СnH2n-2) = D air. (СnH2n-2) * M (air) = 1.862 * 29 = 54 g / mol;
3) Determine the relative molecular weight of the substance:
M (CnH2n-2) = Mr (CnH2n-2) = 54;
4) Determine the molecular formula of the substance:
Mr (CnH2n-2) = Ar (C) * N (C) + Ar (H) * N (H);
54 = 12 * n + 1 * (2n-2);
n = 4;
Unknown substance – C4H6.

Answer: Unknown substance – C4H6.