Derive the molecular formula of the hydrocarbon, if the mass fraction of carbon in this substance

| February 7, 2021 | education

Derive the molecular formula of the hydrocarbon, if the mass fraction of carbon in this substance is 82.75℅, the molar mass is 58 g / mol

1. Let us take the mass of hydrocarbon per 100 g.

2. Let’s find the mass of carbon in the substance.

100 g – 100%,

m (C) – 82.75%

m = (100 g × 82.75%): 100% = 82.75 g.

3. Let’s find the mass of hydrogen.

100 g – 82.75 = 17.25 g

4. Let’s find the amount of matter of atoms in the compound.

n = m: M.

n (H) = 17.25: 1 = 17.25 mol.

n (C) = 82.75: 12 = 6.9 mol.

5. Find the ratio of the amounts of substances.

n (C): n (H) = 6.9: 17.25.

We get: n (C): n (H): n (O) = 1: 2.5.

6. Taking into account that the molar mass of a substance is 58 g / mol, we establish the formula of the substance.

Formula C4H10 – butane.

Answer: С4H10 – butane.



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