Question

What is the molecular formula for a monocyclic hydrocarbon with 10 carbons and 2 triple bonds?

Answer 1

The molecular formula of the hydrocarbon is C₁₀H₁₂.

Explaination: The general molecular formula of monocyclic hydrocarbon with only single bonds between the carbon atoms is C_nH_2n where n is the number of carbon atoms. So, when there is only single bonds between the carbon atoms, the molecular formula of a monocyclic hydrocarbon with 10 carbon atoms will be C₁₀H_2x10 = C₁₀H₂₀.

A tripple bond between any two carbon atoms will displace four hydrogen atoms. So, when there are two tripple bonds in the hydrocarbon, the number of hydrogen atoms reduced will be 2x4 = 8. Therefore, the molecular formula of the hydrocarbon will be C₁₀H_20-8 i.e C₁₀H₁₂.