Ethanol – Preparation, Properties, 9 Important Uses and Tests

Ethanol also known as ethyl alcohol or grain alcohol is an important organic compound and a primary alcohol with the chemical formula CH₃CH₂OH. Ethanol is the exhilarating principle of all wines and is thus named the spirit of wines. Technically it is known as grain alcohol since it is often manufactured from starchy grains. It is used in many daily used products, pharmaceuticals, and industrial solvents.

Preparation of Ethanol

Ethyl alcohol is produced in plants and animals by the fermentation of carbohydrates. Thus it can be detected in traces in plants both in a free state and in the form of esters. In animals, it is found to be present in the tissues, blood, and urine of diabetic patients. It is also present in the human brain to the extent of 0.025 percent.

It can be prepared by any general method of preparation of alcohol. On a commercial scale, it is manufactured by fermentation of carbohydrates or by hydration of alkenes.

Properties of Ethanol

• Ethyl alcohol is a colourless mobile liquid with a characteristic pleasant odour and burning taste.
• It boils at 78.5^oC, freezes at -11^oC, and has a specific gravity of 0.789 at 20^oC.
• It mixes with water in all proportions with the evolution of heat and a contraction in volume. The maximum contraction of 3.6% takes place when 52 volumes of alcohol are mixed with 48 volumes of water.
• It is an excellent solvent for fats, resins, and many more organic substances.
• It also dissolves inorganic substances like caustic soda, caustic potash, sulphur, phosphorous, etc.
• When taken orally in small dosages, alcohol is a good stimulant. It is directly absorbed into the bloodstream and produces heat owing to oxidation hence, it is used as a medicine for contracting cold. If swallowed in large amounts, it acts as a strong poison.
• It gives all the general reactions of alcohol.
• Ethanol has a greater octane number than gasoline, it provides better mixing qualities.

Uses of Ethanol

• Ethanol is used as a fuel for lamps and stoves. For the sake of convenience in transportation, it is converted into a solid state by dispersion in saturated calcium acetate and a little steric acid.
• It is used as a substitute for petrol in internal combustion engines.
• It is used as a solvent for drugs, tinctures, oils, perfumes, inks, dyes, varnishes, etc,
• It is used as a beverage.
• It is used as an antifreeze for automobile radiators.
• It is used as a preservative for biological specimens.
• Ethyl alcohol is also used as a preservative for biological specimens.
• It is used as a low-freezing and mobile fluid in scientific apparatus such as thermometers and spirit levels.
• It can also be used as a raw material for a large number of organic compounds including ethene, ether, acetic acid, iodoform, chloroform, chloral, etc.

Lab tests of ethanol

1. Iodoform test: When ethanol is warmed with iodine and potassium or sodium hydroxide solution, yellow crystals of iodoform are formed. This test can be employed for distinguishing ethyl alcohol from methyl alcohol.
2. Esterification test: Ethanol on warming with anhydrous sodium acetate and concentrated H₂SO₄ forms ethyl acetate which is easily detected by its fruity smell.

Some other forms of ethyl alcohol

1. Industrial alcohol: The alcohol obtained from the fractional distillation of the fermented liquor contains about 95% of ethanol and is called industrial alcohol.
2. Absolute alcohol: 100% pure ethanol is absolute alcohol and it doesn’t contain more than 1% water. This is the kind of alcohol found in alcoholic drinks.
3. Denatured alcohol: Denatured alcohol is the type of alcohol that has been treated using harmful or unpleasant substances making them unsafe for human consumption.
4. Power alcohol: Alcohol combined with petrol and benzene is increasingly utilized as vehicle fuel in non-petroleum-producing states. Alcohol thus used for the generation of power is popularly known as power alcohol.
5. Alcoholic beverages: When alcohol is taken internally in small quantities, it stimulates the human system without any apparent injury effects. The alcohol is consumed in large quantities as alcoholic liquors or beverages. There are mainly two types of beverages, undistilled beverages, and Distilled beverages.

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