alkenes

• • Alkenes are also a type of hydrocarbon like alkanes, but they contain a carbon-carbon double bond.
• • This double bond makes them unsaturated.
• • The general formula for alkenes is CnH2n, where ‘n’ represents the number of carbon atoms.
• • In alkenes, at least two carbon atoms are bonded together by a double bond, while other carbon and hydrogen atoms are bonded by single covalent bonds.
• • The presence of the carbon-carbon double bond causes alkenes to have different physical and chemical properties compared to alkanes.
• • The carbon-carbon double bond is an area of high electron density, making alkenes more reactive than alkanes.
• • Similar to alkanes, alkenes are also insoluble in water due to their non-polar nature, but they can dissolve in organic solvents.
• • Alkenes undergo addition reactions due to the carbon-carbon double bond.
  • For instance, they react with hydrogen in hydrogenation reactions to form alkanes.
  • Another significant reaction of alkenes is with halogens, called halogenation, in which the halogen adds across the double bond.
  • Alkenes also burn in air or oxygen to give carbon dioxide and water, but the combustion is often incomplete, leading to carbon monoxide and soot (carbon).
• • Alkenes are used widely in the chemical industry, especially in the production of polymers or plastics.
  • Ethene is used in the manufacturing of poly(ethene) - often known as polythene.
  • They are also used to manufacture a range of other chemicals, many of which are used to produce consumer goods, such as detergents, solvents or high-octane fuels.
• • Like alkanes, burning alkenes also produces carbon dioxide, a greenhouse gas contributing to global warming.
  • Incomplete combustion producing carbon monoxide can be particularly dangerous as it is a poisonous gas.
  • Large scale manufacture and use of alkenic polymers (plastics) pose significant environmental issues due to their non-biodegradable nature.