Find the molecular formula of the hydrocarbon, the carbon content of which is 89.7%

Find the molecular formula of the hydrocarbon, the carbon content of which is 89.7% and hydrogen 16.3% relative density by hydrogen 43

For the solution, let’s write down the data:

CxNu – hydrocarbon;
W (C) = 89.7%

W (H) = 16.3%

D (H2) = 43;

Determine the formula: CxNy -?

Calculations:
M (CxHy) = D (H2) * M (H2) = 43 * 2 = 86 g / mol.

Let’s determine the amount of carbon, hydrogen:
Y (C) = 89.7 / 12 = 7.4 mol;

Y (H) = 16.3 / 1 = 16.3 mol.

Ratio: C: H = X: Y = 7.4: 16.3 = 1: 2;

The simplest formula CH2 indicates that it belongs to alkanes.

Let’s set the formula:
CnH2n + 2 is the general formula of saturated hydrocarbons.

CnH2n + 2 = 86 g / mol;

12n + 2n = 86 – 2;

14n = 84;

n = 6

C6H14 – hexane

Checking: M (C6H14) = 12 * 6 +14 = 86 g / mol.

Answer: the alkane formula is C6H14 (hexane).