Alcohols are colourless liquids that are soluble in water and form neutral solutions. As the number of carbon atoms in the alcohol increases, their solubility in water decreases. The first four alcohols are often used as fuels, whereas ethanol and ethanol are widely used as solvents.
Alcohols undergo complete combustion in the presence of oxygen to form carbon dioxide and water. This means that we can use them as a source of energy. For example, the combustion of ethanol:
Ethanol + Oxygen → Carbon dioxide + Water
C2H5OH + 3O2 → 2CO2 + 3H2O
When combusted, alcohols release energy.
Alcohols react with sodium to form hydrogen gas and a metal salt. For example, when ethanol reacts with sodium, bubbles of hydrogen gas are produced, and sodium ethoxide is formed.
Ethanol + Sodium → Sodium ethoxide + Hydrogen
2Na + 2C2H5OH → 2C2H5ONa + H2
Alcohols can be chemically oxidised without combustion to produce carboxylic acids, an organic acid. For example, ethanol can be oxidised to ethanoic acid, using an oxidising agent.
Ethanol + Oxidising Agent → Ethanoic acid + Water