The mass fraction of carbon in the hydrocarbon is 83.33%. The density of this substance for hydrogen is 36.

The mass fraction of carbon in the hydrocarbon is 83.33%. The density of this substance for hydrogen is 36. Determine the formula of the hydrocarbon. Write down its isomers.

1. Let the mass of hydrocarbon CxHy:

m (CxHy) = 100 g;

2.Let’s find the masses of hydrogen and carbon in the substance:

m (C) = w (C) * m (CxHy) = 0.8333 * 100 = 83.33 g;

m (C) = m (CxHy) – m (H) = 100 – 83.33 = 16.67 g;

3.Calculate the chemical quantities of C and H:

n (C) = m (C): M (C) = 83.33: 12 = 6.9442 mol;

n (H) = m (H): M (H) = 16.67: 1 = 16.67 mol;

4. Establish the ratio of the number of elements in CхНу:

n (C): n (H) = 6.9442: 16.67;

n (C): n (H) = 1: 2.4;

n (C): n (H) = 5: 12;

5.The simplest formula for HC C5H12, we calculate the relative molecular weight of the hydrocarbon:

Mr (HC) = DH2 (HC) * Mr (H2) = 36 * 2 = 72;

6. find the relative molecular weight of the simplest formula:

Mr (C5H12) = 12 * 5 + 12 = 72;

7. the molecular weight of the simplest formula coincides with the mass of hydrocarbons, that is, the molecular formula corresponds to the simplest formula C5H12.

Answer: C5H12.