2. Hydrocarbons consist of carbon and hydrogen. 5.7 g of a hydrocarbon contains 4.8 g of carbon. If the relative molecular mass of the hydrocarbon is 114, determine its molecular formula.​

The molecular formula of the hydrocarbon compound is C₈H₁₈

Explanation:

The type of chemical substance in the question = Hydrocarbon

The mass of the hydrocarbon = 5.7 g

The mass of carbon in the given hydrocarbon (sample) = 4.8 g

The relative molecular mas of the hydrocarbon = 114 g

Therefore, the mass of hydrogen in the sample, H = 5.7 g - 4.8 g = 0.9 g

The ratio of the mass of carbon in the sample = 4.8/5.7

The ratio of the mass of hydrogen in the sample = 0.9/5.7

By the law of constant composition, we have;

The mass of carbon in a mole of the hydrocarbon = (4.8/5.7) × 114 g = 96 g

The molar mass of carbon, C = 12 g/mol

The number of moles of carbon in a mole of the hydrocarbon, 'n₁', is given as follows;

n₁ = 96 g/12 g = 8 moles

The mass of hydrogen in a mole of the hydrocarbon = (0.9/5.7) × 114 g = 18 g

The molar mass of hydrogen, H ≈ 1 g/mol

The number of moles of hydrogen in a mole of the hydrocarbon, 'n₂', is given as follows;

n₂ = 48 g/1 g = 18 moles

Therefore, in each each molecule of the compound, we have have 8 atoms of carbon, 'C', and 18 atoms of hydrogen, 'H'

Therefore, we get;

The molecular formula of the hydrocarbon compound is C₈H₁₈ which is the chemical formula for the hydrocarbon also known as octane

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: