triple bond are called alkynes. They are also unsaturated as they contain triple bond between carbon atoms. They have the general formula C n H 2n – . Acetylene (C H ) is the simplest alkyne, which contains two carbon atoms.
Table . lists the first five hydrocarbons of each class: Table . Hydrocarbons containing 1to carbon atoms No. of carbon atoms Alkane (C n H 2n + ) Alkene (C n H 2n ) Alkyne (C n H 2n - ) Methane (CH ) Ethane (C H ) Ethene (C H ) Ethyne (C H ) Propane (C H ) Propene (C H ) Propyne (C H ) Butane (C H ) Butene (C H ) Butyne (C H ) Pentane (C H ) Pentene (C H ) Pentyne (C H ) Organic compounds Acyclic or Open chain compounds Cyclic or Closed chain compounds Heterocyclic Compounds (Ring containing carbon and other element) E.g Pyridine, Furan Carbocyclic Compounds (Only cabon ring) Unsaturated (double or triple bond) Ethene CH2 = CH2 Ethyne CH CH Saturated (Compounds containing C-C single bond) E.g.Ethane C2H6 Alicyclic Compounds E.g Cyclobutane Aromatic Compounds E.g Benzene Figure .
Classification of organic compounds . . Characteristics of hydrocarbons: Lower hydrocarbons are gases at room temperature E.g. methane, ethane are gases.
They are colourless and odourless. The boiling point of hydrocarbons increases with an increase in the number of carbon atoms. They undergo combustion reaction with oxygen to form CO and water. Alkanes are least reactive when compared to other classes of hydrocarbons.
Alkynes are the most reactive due to the presence of the triple bond. Alkanes are saturated whereas alkenes and alkynes are unsaturated. They are insoluble in water. Test to identify saturated and unsaturated compounds: Take the given sample solution in a test tube.
Add a few drops of bromine water and observe any characteristic change