The mass fraction of hydrogen in a hydrocarbon molecule is 14.29%, the density of the substance

The mass fraction of hydrogen in a hydrocarbon molecule is 14.29%, the density of the substance in air is 1.93. Determine the molecular formula of the compound

Given:
CxHy – unknown hydrocarbon
ω (H in CxHy) = 14.29%
D air. (CxHy) = 1.93

To find:
CxHy -?

1) M (CxHy) = D air. (CxHy) * M (air) = 1.93 * 29 = 56 g / mol;
2) Mr (CxHy) = M (CxHy) = 56;
3) ω (C in CxHy) = 100% – ω (H in CxHy) = 100% – 14.29% = 85.71%;
4) x = (ω (C in CxHy) * Mr (CxHy)) / (Ar (C) * 100%) = (85.71% * 56) / (12 * 100%) = 4;
5) y = (ω (H in CxHy) * Mr (CxHy)) / (Ar (H) * 100%) = (14.29% * 56) / (1 * 100%) = 8;
6) Unknown hydrocarbon – C4H8.

Answer: Unknown hydrocarbon – C4H8.