Establish the molecular formula of the hydrocarbon if it is known that the total content of 80 percent C

Establish the molecular formula of the hydrocarbon if it is known that the total content of 80 percent C, 20 percent H, the relative density of vapor in air is 1.034.

Given:
HC
ω (C in HC) = 80%
ω (H in HC) = 20%
D air. (HC) = 1.034

Find:
UV -?

Solution:
1) Calculate the molar mass of HC:
M (HC) = D air. (HC) * M (air) = 1.034 * 29 = 30 g / mol;
2) Determine the relative molecular weight of hydrocarbons:
Mr (HC) = M (HC) = 30;
3) Calculate the index of C atoms in the SW:
N (C in HC) = (ω (C in HC) * Mr (HC)) / (Ar (C) * 100%) = (80% * 30) / (12 * 100%) = 2;
4) Calculate the index of H atoms in the SW:
N (H in HC) = (ω (H HC) * Mr (HC)) / (Ar (H) * 100%) = (20% * 30) / (1 * 100%) = 6;
Unknown substance – C2H6.

Answer: Unknown substance – C2H6.