The hydrocarbon has a density by air of 1.034 mass fraction of carbon in it 80% determine the carbon formula.

Given:
CxHy
D air. (CxHy) = 1.034
ω (C in CxHy) = 80%

Find:
CxHy -?

Solution:
1) M (CxHy) = D air. (CxHy) * M (air) = 1.034 * 29 = 30 g / mol;
2) Mr (CxHy) = M (CxHy) = 30;
3) N (C in CxHy) = (ω (C in CxHy) * Mr (CxHy)) / (Ar (C) * 100%) = (80% * 30) / (12 * 100%) = 2;
4) ω (H in CxHy) = 100% – ω (C in CxHy) = 100% – 80% = 20%;
5) N (H in CxHy) = (ω (H in CxHy) * Mr (CxHy)) / (Ar (H) * 100%) = (20% * 30) / (1 * 100%) = 6;
6) Unknown substance – C2H6 – ethane.

Answer: Unknown substance – C2H6 – ethane.