A hydrocarbon, the mass fraction of carbon in which is 85.7% and having a hydrogen vapor density of 28, is …

Given:
CxHy
ω (C in CxHy) = 85.7%
D H2 (CxHy) = 28

Find:
CxHy -?

Solution:
1) M (CxHy) = D H2 (CxHy) * M (H2) = 28 * 2 = 56 g / mol;
2) Mr (CxHy) = M (CxHy) = 56;
3) N (C in CxHy) = (ω (C in CxHy) * Mr (CxHy)) / (Ar (C) * 100%) = (85.7% * 56) / (12 * 100%) = 4 ;
4) ω (H in CxHy) = 100% – ω (C in CxHy) = 100% – 85.7% = 14.3%;
5) N (H in CxHy) = (ω (H in CxHy) * Mr (CxHy)) / (Ar (H) * 100%) = (14.3% * 56) / (1 * 100%) = 8 ;
6) Unknown substance – C4H8 – butene.

Answer: Unknown substance – C4H8 – butene