7.2.2

Reactions of Alkenes

Test yourself

Examples of Alkene Addition Reactions

Alkenes are involved in addition reactions with different substances:

Illustrative background for Alkenes and oxygenIllustrative background for Alkenes and oxygen ?? "content

Alkenes and oxygen

  • Alkenes can be involved in combustion reactions with oxygen. The outcome of these reactions is similar to when other hydrocarbons react with oxygen.
    • E.g. Ethene (C2H4) + oxygen (O2) → carbon monoxide (CO) + carbon (C) + water (H2O)
  • Because their combustion is incomplete, they burn with smoky flames.
Illustrative background for Alkenes and hydrogenIllustrative background for Alkenes and hydrogen ?? "content

Alkenes and hydrogen

  • When a nickel catalyst is present, alkanes can be formed by combining hydrogen with an alkene.
  • E.g. Ethene (C2H4) + hydrogen (H2) → ethane (C2H6)
  • Adding hydrogen atoms across a carbon-carbon double bond is called hydrogenation.
Illustrative background for Alkenes and waterIllustrative background for Alkenes and water ?? "content

Alkenes and water

  • When a phosphoric acid catalyst is present, alcohols can be formed by reacting alkenes with steam.
    • E.g. Ethene (C2H4) + steam (H2O) → ethanol (C2H5OH)
Illustrative background for Alkenes and halogensIllustrative background for Alkenes and halogens ?? "content

Alkenes and halogens

  • Alkenes, unlike alkanes, will react if mixed with bromine water and shaken. This causes the solution to change colour from orange-brown to colourless.
    • E.g. Ethene (C2H4) (colourless) + bromine (Br2) (orange-brown solution) → dibromoethane (CH2BrCH2Br) (colourless)
  • This is an effective test for distinguishing between alkenes and alkanes.

Jump to other topics

1Atomic Structure

2Chemical Bonding

3Quantitative Chemistry

4Chemical Changes

5Energy Changes

6The Rate & Extent of Chemical Change

7Organic Chemistry

8Chemical Analysis

9Chemistry of the Atmosphere

10Using Resources

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