Molecular formula of hydrocarbon that contains 80% carbon by mass is

The molecular formula of a hydrocarbon that contains 80% carbon by mass can be determined by following these steps:

1. Assume the total mass of the hydrocarbon is 100g. This means that there are 80g of carbon and 20g of hydrogen.

2. Convert these masses into moles by dividing by the atomic mass of each element. The atomic mass of carbon (C) is approximately 12g/mol and the atomic mass of hydrogen (H) is approximately 1g/mol. Therefore, there are 80g/12g/mol = 6.67 mol of carbon and 20g/1g/mol = 20 mol of hydrogen.

3. The ratio of moles of hydrogen to moles of carbon is 20:6.67, which simplifies to approximately 3:1.

4. Therefore, the empirical formula of the hydrocarbon is CH3.

5. The molecular formula of a compound is a multiple of its empirical formula. In this case, the molecular formula is also CH3, because the ratio of carbon to hydrogen is 1:3, which matches the ratio in the empirical formula.

So, the molecular formula of the hydrocarbon that contains 80% carbon by mass is CH3.