Alcohol

Alcohol is a word generally used to describe Ethylene Alcohol or Ethanol, which is the product found in alcoholic drinks, in certain food recipes, and in laboratories. The word Alcohol is also used to designate all alcoholic drinks, such as wine, beer and champagne. We sometimes say, for example, that whisky, is a very strong alcohol, to signify that it's a strongly alcoholic drink; the official term is spirits.

In chemistry, the term alcohol designates an entire family of molecules, including those of a specific group: the Hydroxyl group (OH).

Chemical properties

Ethanol is a solvent with the chemical formula C₂H₆O, which permits the dissolution or dilution of numerous fatty and aromatic chemical substances. It can be mixed in all proportions with water. In its normal condition, it's a completely colourless liquid, which possesses a characteristic odour, and it's highly flammable. It evaporates very easily: if you get it on your skin, you can feel that it's cold. It is thanks to this property that we can distill alcohol. If you heat a mixture of ethanol and water, the ethanol evaporates much quicker than the water. If you pass the ethanol vapours through a cold tube, it permits the evaporated alcohol to become liquid again (condensation). The molecules of the alcohol family are characterised by a hydroxyl function, a group formed of one atom of Oxygen and one atom of Hydrogen (-OH).

Domestic uses

Modified camphorated ethanol - over the counter in pharmacies - is a good disinfectant. It destroys bacteria and many other microbes in an instant. But on damaged, cut, or scratched skin, ethanol stings a lot! On healthy skin, you feel a cold sensation (the cold is caused by the heat that ethanol absorbs to evaporate). It is this ethanol that the nurse uses on your skin before giving you an injection.

Ethanol can also be used as a household solvent, to remove traces of glue, such as under a plaster for example. However, care must be taken to ventilate the room well: ethanol evaporates easily and the vapours from it can make you drunk.

Ethanol is sometimes used as a fire starter for a barbecue. It is highly flammable and very dangerous!

Use as fuel

For some years now there have been cars and trucks in some countries around the world, such as Brazil, that can use an ethanol / gasoline blend to operate. This ethanol is produced from cultivated plants such as sugar cane or rapeseed. It is a way of limiting the consumption of oil which is a non-renewable energetic resource.

Biological properties

Origin and biological fate

Ethanol is produced from the fermentation of sugars by a yeast. Most living organisms are able to convert ethanol to acetic acid. In humans, this mainly occurs in the liver.

To produce an alcoholic beverage, you need a juice containing sugar (such as sucrose, which is powdered sugar) or starch, which is contained for example, in potatoes. A microbe is added to the juice which is capable of making alcoholic fermentation. The most common is brewer's yeast. Then, you have to wait varying lengths of time, depending on the sugar concentration and the strength of alcohol you want.

In industry, it is possible to produce large quantities of ethanol from the cellulose contained in wood and plants. The process is complex but very efficient.

Direct toxic effect

Ethanol is a poison for all forms of life, which is why it is used as a disinfectant or local antiseptic in the form of modified camphorated alcohol. Ethanol destroys the membranes of cells, which kills them.

Indirect toxic effect

If you ingest ethanol, the body tries to fight off the poison by turning it into Acetaldehyde and then Acetic acid (found in vinegar). Ethanol itself and Acetaldehyde are both poisons for cells, and more particularly for nerve cells: even at low concentration they disturb the functioning of nerves, which causes "intoxication" or "drunkenness". Drunkenness is a phenomenon where all normal reactions are slowed down, with or without changes in behaviour or disturbances of consciousness. The slowing of reactions can range from a simple lengthening of the reflexes to coma, then to death. It is the role of the liver to eliminate alcohol. The lungs are also involved in removing alcohol from the blood.

A person who has drunk alcohol breathes some of it out. The amount he exhales is proportionate to the amount he has in the blood. We can therefore blow someone into a balloon and measure the level of alcohol ingested. This is useful for detecting people who have been drinking alcohol and driving a car, putting their lives and those of others at risk.

Mammals can survive varying doses of ethanol. For example, a thimble of ethanol (a few millilitres) can kill a rabbit. If ethanol is introduced regularly and in small doses, the organism becomes able to survive in increasing doses. But the drunkenness remains, which endangers the drunken person and anyone with them because of their reduced reflexes (road accidents) and the modification of their behaviour (violent or aggressiveness).

Regular consumption of ethanol causes changes in the body, which adapts to fight the poison. The main organ in this fight is the liver, which becomes exhausted and becomes ill (a condition called Cirrhosis). There may even be cancer of the liver. But other organs are affected: the heart, blood vessels, stomach, pancreas and the whole digestive tract, as well as the brain, which can suffer irreversible damage.

Alcohol consumption during pregnancy is very dangerous for a growing baby (foetus) which is unable to resist the toxic effects of alcohol. Babies which grow when a mother is drinking alcohol, are often born with learning or physical disabilities, such as deafness or blindness. This is an illness called Foetal Alcohol Syndrome.

Alcohol is also used as a treatment for methanol poisoning.

Alcoholic drinks

Ethanol is present in all alcoholic beverages, at a higher or lower concentration, such as cider, wine, etc. It comes from the fermentation of a juice, often from a plant rich in sugar, (apple juice, grape juice , but also potato) juice and sometimes even milk: the more sugar the juice contains, the more alcohol the drink obtained may contain.

The ethanol concentration must appear on the bottle: it is measured in percent or in alcoholic degrees (proof).

The various alcoholic drinks are traditionally served in specific glasses. Per type of drink the standard glass contains approximately 10 grams of alcohol. Thus, a cup or flute of champagne moderately filled (that is to say about 100 millilitres of liquid) contains as much alcohol as a glass of wine at 12% (that is to say, how much alcohol the drink contains).

A glass of 5% beer on tap, or a bottle, or about 250 millilitres of liquid, also contains 10 grams of alcohol. A shot of whisky at 40% (or 30 millilitres of liquid) or a dose of pastis at 45% (or approximately 30 millilitres of liquid), also contain 10 grams of alcohol. Adding water or ice cubes to these last two drinks does not affect the amount of alcohol they contain.

Drug addiction

Regular consumption of ethanol is a disease called alcoholism or alcoholic illness. Alcohol is a drug, that is to say it modifies the perception that we have of the world by acting on the brain. Ethanol has been consumed for thousands of years (back to about 7000 BCE) for its actions on the soul. The modification of behaviour, consciousness and mood, as well as the relaxation perceived by the drunken person is sometimes experienced as pleasant (sometimes also unpleasant) but is addictive: after a short time, one cannot do without 'alcohol. This addiction is impossible to avoid, and very hard to lose. This is why it is very important to control how much alcohol you drink.