Ethanol(C₂H₅OH) is a part of a family of organic compounds called the alcohols . Using ethanol in alcoholic drinks has a long history. It is used as a fuel for cars in countries such as Brazil, which is a more recent development.

Ethanol is readily produced in nature and has long been part of human society. Ethanol is the intoxicating element of alcoholic drinks, which is toxic in high concentrations.

Ethanol is widely used as an industrial solvent. For many years, ethanol intended for this purpose was made by fermentation, but today industrial–grade ethanol is more cheaply manufactured from petroleum by–products, such as ethene phosphoric acid used as a catalyst. The liquid produced by fermentation has an ethanol concentration not greater than about 12 percent because at this concentration the yeast begins to die. This is why most wines have an alcohol content of 11 or 12 percent–they are produced solely by fermentation. To attain the higher ethanol concentrations found in such “hard” alcoholic beverages as gin and vodka, the fermented liquid must be distilled.

Ethanol when taken internally can act as a addictive drug, which can lead to long term heavy drinking. This causes chronic liver disease and brain damage, eventually leading to death. Breath analyzer used to test drivers suspected of being drunk. The chemical basis of this device is a redox reaction.
3CH₃CH₂OH + 2K₂Cr₂O₇ + 8H₂SO₄
3CH₃COOH+2Cr₂(SO₄)₃ + 2K₂SO₄ + 11H₂O
In this reaction the ethanol is oxidized to acetic acid and the chromium(VI)in the orange–yellow dichromate ion is reduced to the green chromium(III) ion.

The use of ethanol as a fuel source for vehicles replaces highly polluting fuels derived from dwindling supplies of fossil fuels, which releases the green house gases.In countries like Brazil, crops such as sugar cane are being grown to be fermented on an industrial scale to produce ethanol not for drinking but as a renewable fuel source for vehicles. Alcohol is completely burnt when heated in presence of oxygen in the air. Alcohols undergo complete combustion to give carbon dioxide and water, making them a very clean fuel.

Physical properties of ethanol:
Ethyl alcohol is colorless liquid with a characteristic pleasant odor and burning taste. It boils at 78.1°C and has specific gravity 0.8. It is miscible with water in all proportions, and is also miscible with most organic solvents. When ethyl alcohol and water are mixed, a contraction in volume occurs. It is an excellent solvent for fats, resins and inorganic substances like caustic soda, caustic potash, sulfur, iodine and phosphorus.

The bittering agents such as denatonium benzoate and toxins such as methanol, naphtha, and pyridine.etc.,are added to ethanol to produce products for uses other than human consumption and Products of this kind are called denatured alcohols.

Absolute or anhydrous alcohol refers to ethanol with low water content. These are in various grades with maximum water contents ranging from 1% to ppm levels. These are unfit for human consumption. Absolute ethanol is used as a solvent for laboratory and industrial applications. Rectified spirit, an azeotropic composition containing 4% water, is used instead of anhydrous ethanol for various purposes. Wine spirits are about 188 proof. The impurities are different from those in 190 proof laboratory ethanol

The ethanol content of alcoholic beverages is measured as proof, which is twice the percent ethanol. An 86–proof whiskey, for example, is 43 percent ethanol by volume. The determination of the strength of alcohol is called ‘alcoholometry’.

Uses:

• As a preservative for biological specimens.
• In the preparation of essences and flavorings.
• In many medicines and drugs.
• As a disinfectant and in tinctures (eg: Tincture of iodine).

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