Alkenes

Question 1

Define alkenes

Answer 1

Alkenes, also called olefins, are

hydrocarbons which contain one or more carbon-carbon double bond(s). They are unsaturated hydocarbons

Question 2

Classification of alkenes

Answer 2

1) Monenes. They have the general
formula CnH2n.
2) Diolefins or alkadienes or dienes. They have the general formula CnH2n-2 
3) Trienes have three double bonds
4) Tetraene have four double bonds
5) Polyene is used for hydrocarbons
containing more than four double bonds

Question 3

Physical properties of alkenes

Answer 3

Properties of alkenes are similar to those of the corresponding alkanes.

1) The boiling points of a homologous
series of alkenes increase 20-30K per CH2 group except for the very
homologues.
2) Branching in an alkene also lowers the
boiling point.
3) Lower alkenes, from ethane to butane, are colourless gases, higher ones, from C5 - C15, are liquids and the rest are solids at temperature.