Hydrocarbon contains 75% carbon, the vapor density of this substance for oxygen is equal to 0.5

Hydrocarbon contains 75% carbon, the vapor density of this substance for oxygen is equal to 0.5 determine the formula of the substance

Let’s write down the solution:
1. Let’s designate hydrocarbon: CxNu.
2. Let’s calculate its molar mass by the formula:
M (CxHy) = M (O2) * D (O2) = 32 * 0.5 = 16 g / mol.
3. Determine the amount of carbon, hydrogen:
Y (C) = m / M = 75/12 = 6.25 mol;
m (H) = 100 – 75 = 25 g;
Y (H) = m / M = 25/1 = 25 mol.
4. The ratio: X: Y = C: H = 6.25: 25 = 1: 4, thus, the simplest formula – CH4 belongs to the hydrocarbon methane. M (CH4) = 16 g / mol.
5. Verification: CnH2n + 2 = 16;
12n + 2 + 2 = 16;
12n = 12;
n = 1 hence, the molecular formula is CH4.
Answer: CH4 is methane.