Alkanes

General molecular formula of alkanes is C_nH_2n+2. These are saturated hydrocarbons.  They contain C-C and C-H bonds. They are commonly known as paraffins due to their less reactivity.

Hydrocarbons with one or more carbon rings in their molecules with only C–C single bonds and sp³ hybridised carbon atoms are cycloalkanes. Cycloalkanes with only one ring have the general formula C_nH_2n.

Physical Properties of Alkanes

Alkanes are nonpolar hence only weak Vanderwaals forces of attraction exist between their molecules.

They possess very low boiling and melting points.

At 298K, first four members (C₁ - C₄) are gases, C₅ - C₁₇ are liquids and above C₁₇ are solids.

They are soluble in non-polar solvents.

Chemical Properties

Halogenation

Nitration: Ethane reacts with con. HNO₃ at 400°C to give nitro ethane.

Pyrolysis: Strong heating in the absence of air is called pyrolysis or cracking.

Isomerisation: Formation of branched chain isomers from higher alkanes on heating in the presence of anhydrous AlCl₃ and HCl gas is isomerisation.

Aromatisation or reforming

Combustion: Any hydrocarbon on combustion gives CO₂ and H₂O.