Properties of Alkanes
Chemistry: Cambridge International GCSE Supplement, topic 11.4.2
Properties of Alkanes
Alkanes have single covalent bonds, are saturated hydrocarbons, and they mainly react by combustion or substitution with chlorine.
What are alkanes?
- Alkanes are hydrocarbons containing only single covalent bonds.
- Alkanes are considered saturated hydrocarbons because each carbon atom forms four single bonds.
- The simplest alkane is methane.
- Alkanes follow the general formula CnH2n+2.
Bonding in alkanes
- Alkanes have single covalent bonds between carbon and hydrogen atoms.
- Each carbon atom in alkanes forms four single bonds with other atoms.
- Single covalent bonds make the alkane structure stable.
- All bonds in alkanes allow free rotation around the carbon-carbon bonds.
Reactivity of alkanes
- Alkanes are generally unreactive due to their strong single covalent bonds.
- Alkanes burn easily in oxygen; this is called combustion.
- During complete combustion, alkanes produce carbon dioxide and water.
- Alkanes react with chlorine in sunlight through substitution reactions.
Combustion of alkanes
- Combustion is an important reaction of alkanes for energy.
- Alkanes release energy when they burn in oxygen.
- Incomplete combustion produces carbon monoxide, which is dangerous.
Substitution reactions with chlorine
- Alkanes react with chlorine under UV light by substitution.
- In substitution, hydrogen atoms are replaced by chlorine atoms.
- Chlorination changes the properties of the original alkane molecule.