Establish the molecular formula of organic matter if the mass fractions of carbon

Establish the molecular formula of organic matter if the mass fractions of carbon, hydrogen and oxygen in it are, respectively, 60%, 13.33% and 26.67%. The hydrogen vapor density of the substance is 30

Given:
CxHyOz
ω (C in CxHyOz) = 60%
ω (H in CxHyOz) = 13.33%
ω (O in CxHyOz) = 26.67%
D H2 (CxHyOz) = 30

Find:
CxHyOz -?

Solution:
1) M (CxHyOz) = D H2 (CxHyOz) * M (H2) = 30 * 2 = 60 g / mol;
2) Mr (CxHyOz) = M (CxHyOz) = 60;
3) N (C in CxHyOz) = (ω (C in CxHyOz) * Mr (CxHyOz)) / (Ar (C) * 100%) = (60% * 60) / (12 * 100%) = 3;
4) N (H in CxHyOz) = (ω (H in CxHyOz) * Mr (CxHyOz)) / (Ar (H) * 100%) = (13.33% * 60) / (1 * 100%) = 8 ;
5) N (O in CxHyOz) = (ω (O in CxHyOz) * Mr (CxHyOz)) / (Ar (O) * 100%) = (26.67% * 60) / (16 * 100%) = 1 ;
Unknown substance – C3H8O.

Answer: Unknown substance – C3H8O.