What is the general formula of alkynes?

Alkynes are unsaturated hydrocarbons that contain at least one carbon–carbon triple bond (–C≡C–) in their structure. The presence of this triple bond gives alkynes unique chemical and physical properties compared to alkanes and alkenes. The general formula of alkynes is CₙH₂ₙ₋₂. This means that for every “n” carbon atoms, there are “2n−2” hydrogen atoms.

This formula reflects the degree of unsaturation in alkynes. Each triple bond reduces the hydrogen count by four compared to alkanes, which follow the formula CₙH₂ₙ₊₂. For example, ethyne (acetylene), the simplest alkyne, has two carbon atoms and two hydrogen atoms (C₂H₂), which fits the general formula CₙH₂ₙ₋₂ when n = 2.

The triple bond in alkynes consists of one sigma (σ) bond and two pi (π) bonds formed by the overlap of sp-hybridized orbitals. This bond arrangement makes alkynes linear in shape and gives them a bond angle of about 180°. Because of the strong π bonds, alkynes show characteristic reactions such as addition, oxidation, and combustion.

Alkynes are important in both laboratory and industrial chemistry. They serve as building blocks in the synthesis of many organic compounds, including alcohols, aldehydes, and polymers. Common examples include ethyne (C₂H₂), propyne (C₃H₄), and butyne (C₄H₆).