Derive the formula for a hydrocarbon, the carbon content of which is 85.71%, and the relative

Derive the formula for a hydrocarbon, the carbon content of which is 85.71%, and the relative density for hydrogen is 63. Name the substance.

Given:

w% (C) = 85.71%

D (H2) = 63

Find:

Formula -?

Solution:

1) Find the molecular weight of the hydrocarbon by its hydrogen density:

D (H2) = Mr (SW): Mr (H2)

Mr (HC) = D (H2) * Mr (H2) = 63 * 2 = 126

2) Knowing the mass fraction of carbon, we find its molecular weight and the number of atoms:

126 – 100%

x – 85.71%,

x = 85.71% * 126: 100% = 108.

N (C) = 128: Mr (C) = 108: 12 = 9 atoms.

3) Then the molecular weight of hydrogen accounts for 126 – 108 = 18

N (H) = 18: Mr (H) = 18: 1 = 18 atoms.

We got a substance with the formula C9H18 – nonene.

Answer: С9Н18 – nonen.