Chemistry GCSE Edexcel - C3

• Alcohols have a functional group -OH
• Their general formula is CnH(2n+1)OH
• The first four alcohols are: methanol, ethanol, propanol and butanol

Alcohols are:

• flammable (burning to produce carbon dioxide and water)
• volatile (they evaporate easily)
• miscible with water (only the first three)
• toxic

The carbon chain allows alcohols to mix with oils and the -OH functional group allows them to mix with water. This means that they are very good solvents.

• used in the solvents for perfumes and aftershaves

• meths (ethanol, methanol and blue dye) is used to clean brushes and as a fuel

• ethanol is used in spirit burners

• 'gasohol' is used in some countries as a greener alternative to petrol - ethanol and petrol mixed together.

• Carboxylic acids (organic acids) have a functional group -COOH
• First four are methanoic acid, ethanoic acid, propanoic acid and butanoic acid

Carboxylic acids:

• are miscible with water (but the longer the chain, the less miscible it is)
• are miscible with alcohol
• react like most acids, forming salts
• are corrosive

• ethanoic acid is in vinegar

• citric acid is in lemons and oranges, used in fizzy drinks and in kitchen descaler

• aspirin

• to make esters

• to make soaps and detergents

• good solvent (but often not chosen as it makes the solution acidic)

• Esters have a functional group -COOH-
• formed from an alcohol and a carboxylic acid:
  • alcohol + carboxylic acid => ester + water

Esters:

• smell nice
• mix with alcohol but not water
• are colourless liquids with low boiling points
• are volatile
• are flammable

• perfumes

• flavourings and aromas

• ointments (e.g. Deep Heat)

• solvents in paint, ink, glue and nail varnish remover

SAFETY ISSUES

• fumes can irritate mucus membranes in the nose and mouth
• very flammable
• toxic in large doses