The organic compound contains 80% carbon and 20% hydrogen. The relative density

The organic compound contains 80% carbon and 20% hydrogen. The relative density in air is 1.034. Determine the molecular formula of the substance.

By the condition of the problem, given:
W (C) = 80%
W (H) = 20%
D (air) = 1.034;
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1. Let us determine the molar mass of the hydrocarbon, if the density is known:
M (CxHy) = M (air) * D (air) = 29 * 1.034 = 29.9 = 30 g / mol.
2. Find the number of moles:
Y (C) = m / M = 80/12 = 6.6;
Y (H) = m / M = 20/12 = 1.6.
3. Ratio:
C: H = X: Y = 6.6: 1.6 = 4: 1;
The simplest formula: CH4;
Organic matter belongs to the class of alkanes.
4. Molecular formula: C2H6;
Checking: M (C2H6) = 30 g / mol.
Answer: C2H6 is ethane.