Hydrocarbons

Hydrocarbons Overview

  • Hydrocarbons are organic compounds made entirely of hydrogen and carbon atoms.
  • They are the primary components of fossil fuels like coal, natural gas, and petroleum.
  • Hydrocarbons are sorted into two main groups: saturated and unsaturated hydrocarbons.

Saturated Hydrocarbons

  • Saturated hydrocarbons, also known as alkanes, contain only single bonds between atoms.
  • Alkanes are considered “saturated” as they are holding the maximum number of Hydrogen atoms possible.
  • The general formula for an alkane is CₙH₂ₙ₊₂. E.g., methane (CH₄), ethane (C₂H₆).

Unsaturated Hydrocarbons

  • Unsaturated hydrocarbons have double or triple bonds between Carbon atoms.
  • They are divided into alkenes (contain a carbon-carbon double bond) and alkynes (contain a carbon-carbon triple bond).
  • General formula for alkenes is CₙH₂ₙ (e.g., ethene C₂H₄), and for alkynes is CₙH₂ₙ₋₂ (e.g., ethyne C₂H₂).

Properties of Hydrocarbons

  • Physical properties of hydrocarbons are largely determined by the type and strength of the intermolecular forces.
  • Alkanes are non-polar, hence, generally insoluble in water but soluble in organic solvents.
  • Alkenes and alkynes are more reactive than alkanes due to the presence of double and triple bonds respectively.

Reactions of Hydrocarbons

  • Common reactions of hydrocarbons include combustion, substitution and addition reactions.
  • In combustion, hydrocarbons react with oxygen to produce carbon dioxide and water, along with energy.
  • In substitution reactions of alkanes, a hydrogen atom is replaced by a different atom or group of atoms.
  • Addition reactions primarily occur with unsaturated hydrocarbons. The double or triple bond opens up to form single bonds and new atoms are added.

Uses of Hydrocarbons

  • Hydrocarbons have a wide range of uses including as fuels (methane, petrol), in polymers (ethylene in polyethylene), and as solvents (hexane).
  • Many hydrocarbons are key starting materials for the synthesis of a wide variety of chemicals in the chemical industry.
  • The chains and structures of hydrocarbons can be modified in the laboratory to create artificial compounds with specific desirable properties.