alcano

An alcano, in chemistry commonly called an alkane, is a saturated acyclic hydrocarbon that contains only single bonds between carbon atoms. The general formula is CnH2n+2, where n is the number of carbon atoms. Alkanes form a homologous series, beginning with methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10), with each successive member adding a CH2 unit. This regular progression leads to gradual changes in physical properties and increasing molecular complexity.

Alkanes are nonpolar and exhibit relatively low reactivity. They are insoluble in water but soluble in nonpolar solvents. Short-chain alkanes at room temperature are gases; medium chains are liquids; long chains become waxy solids. Their chemistry is dominated by combustion, where complete burning yields carbon dioxide and water. In substitution reactions, especially under ultraviolet light, alkanes can react with halogens to form haloalkanes and hydrogen halides, though such reactions require energy input and are less common for larger alkanes.

Occurrence and production: alkanes occur naturally in fossil fuels, notably natural gas and crude oil, and are extracted and refined for use as fuels and feedstocks. Uses: they serve as fuels for heating, electricity generation, and transportation, as well as starting materials in the chemical industry and as lubricants in some forms.

Environmental considerations include their role as greenhouse gases, particularly methane when released unburned, and their contribution to atmospheric warming if flared or leaked.