How to detect whether a given liquid contains alcohol or not ?

Alcohols can be identified by one of the following tests:

1. Sodium Metal Test:

Alcohols can be distinguished from other organic compounds, which do not contain acidic group, by this test. A small piece of sodium metal is added to the compound. If hydrogen gas is produced with effervescence, it indicates the presence of alcohols. It may be noted that alcohols cannot be distinguished from carboxylic acids by this test.

2. Ester Test

In this test, the compound to be tested is warmed with acetic acid and a few drops of conc. H₂SO_4. Formation of sweet smelling vapours of some ester indicates the presence of alcohol.

3. Oxidation Test

In this test, the compound to be tested is warmed with acidified potassium dichromate solution. If the colour changes from orange to green, this indicates the presence of some alcohol.

Similarly, the compound may be warmed with acidified potassium permanganate test. The change of colour from pink to colourless indicates the presence of some alcohol.

Uses of Ethanol

1. Ethyl alcohol is a constituent of alcoholic beverages such as beer, wine, whisky and other liquors.

2. A mixture of alcohol and water has much lower freezing point than that of water. This mixture is known as antifreeze and is used in radiators of vehicles in cold countries.

3. It is also used as solvent for resins, fats, oils, fatty acids and hydrocarbons.

4. Ethyl alcohol is used to sterilise wounds and synergies.

5. In the manufacture of dyes, drugs and detergents.

6. As a petrol substitute. Ethanol can be mixed with petrol to the extent of 25% and used as fuel in internal combustion engines.