AQA GCSE FOUNDATION Chemistry: Alkanes and Saturated Hydrocarbons

AQA GCSE Foundation Chemistry: Alkanes and Saturated Hydrocarbons

What are Alkanes?

Alkanes are a type of hydrocarbon, which means they are molecules made up of only carbon (C) and hydrogen (H) atoms. They are known as saturated hydrocarbons because they have the maximum possible number of hydrogen atoms bonded to each carbon atom.

General Formula of Alkanes

The general formula for alkanes is CnH2n+2, where 'n' represents the number of carbon atoms in the molecule.

Naming Alkanes

Alkanes are named based on the number of carbon atoms they contain:

Structural Formulas of Alkanes

Alkanes can be represented using structural formulas, which show the arrangement of atoms in a molecule. For example:

Methane (CH4):

     H
     |
  H - C - H
     |
     H

Ethane (C2H6):

    H  H
    |  |
H - C - C - H
    |  |
    H  H

Propane (C3H8):

    H  H  H
    |  |  |
H - C - C - C - H
    |  |  |
    H  H  H

Properties of Alkanes

• Non-polar: Alkanes have very weak intermolecular forces due to their non-polar nature. This results in low boiling points and melting points.
• Insoluble in water: Alkanes are not soluble in water because they are non-polar, while water is a polar solvent.
• Combustible: Alkanes readily burn in air, releasing energy in the form of heat and light.
• Relatively unreactive: Alkanes are relatively unreactive due to the strong carbon-hydrogen bonds. They do not readily participate in reactions like addition or substitution reactions.

Uses of Alkanes

Alkanes have numerous uses in everyday life:

• Fuels: Methane, propane, and butane are commonly used as fuels for heating and cooking.
• Petrochemicals: Alkanes are the starting materials for the production of many important chemicals, including plastics, detergents, and fertilizers.
• Solvents: Some alkanes, like hexane and heptane, are used as solvents in industrial processes.

Summary

Alkanes are a fundamental class of organic compounds with diverse applications. Their properties, determined by their non-polar nature and strong carbon-hydrogen bonds, make them valuable fuels and starting materials for numerous industries. Understanding the structure and properties of alkanes is crucial for comprehending the behavior and uses of these important molecules.