How can you distinguish between alkanes, alkenes and alkynes?

1 Answer

Alkanes have single bonds between carbons in a hydrocarbon. Alkenes have double bonds between carbons.
Alkynes have triple bonds between carbons.

Explanation:

Alkanes have single bonds between carbons in a hydrocarbon. A quick way to recognize an alkane is the general formula: #"C"_ n"H"_(2n+2)#.

Examples:

  • methane, #"CH"_4#
  • ethane, #"C"_2"H"_6#
  • propane, #"C"_3"H"_8#
  • butane, #"C"_4"H"_10#

Alkenes have double bonds between carbons. A quick way to recognize an alkene is its general formula: #"C"_ n"H"_(2n)# .

Examples:

  • ethene, #"C"_2"H"_4#
  • propene, #"C"_3"H"_6#
  • butene, #"C"_4"H"_8#

And alkynes have triple bonds between carbons. A quick way to recognize an alkynes is its general formula: #"C"_ n"H"_(2n-2)#.

Examples:

  • ethyne, #"C"_2"H"_2#
  • propyne, #"C"_3"H"_4#
  • butyne, #"C"_4"H"_6#