The moment we say alcohol, the first thing that comes to our mind is drink... However, alcohol has better uses and is more than just a drink. Let us find out more about this important thing...
How is alcohol made?
Whether it is made as wine or beer, the method of production is essentially the same. A carbohydrate, such as starch or sugar, is broken down into glucose form and is then mixed with yeast and allowed to ferment for weeks or even months. Catalysts within the yeast then convert the glucose into alcohol and carbon dioxide thereby releasing the energy that the yeast needs in order to survive and grow.
Yeast can normally tolerate a concentration of up to about 12 per cent of what is, in effect, a waste product of its energy generation. This puts an upper limit on the alcohol content of wine or beer. To increase this, the fermented liquor needs to be distilled. As the boiling point of alcohol is 78 degrees Celsius as compared with 100 degrees Celsius for water, the liquid that distils contains a higher proportion of alcohol than the original wine or beer. This is how spirits such as whiskey, brandy, vodka etc. are made.
Uses of Some Alcohols
Alcohols are not just drinks but are widely used as solvents. This is because of its ability to dissolve many substances that cannot be dissolved in water. Ethanediol (ethylene glycol), an alcohol, is used as anti-freeze, to prevent water from freezing in car radiators. The sweet tasting glycerol (glycerine) is an alcohol which is made as a by-product of the manufacture of soap from fats or oils. Ethanol has a boiling point which is similar to that of petrol. It burns very well with a clean flame, and can therefore be used as a fuel.
Oxidation of Alcohols
If the stopper is left off a bottle of wine or spirits, for a few days, the drink turns sour. This is caused by oxygen in the air, which oxidises the ethanol to ethanoic, or acetic acid, more commonly known as vinegar.
Oxidation of alcohols to organic acids like vinegar is a two-stage process, the intermediate compound being an aldehyde. Methanol, for example, is oxidised to methanal (formaldehyde), and is used to preserve dead biological specimens and organs for use in scientific research. The oxidation of methanal produces methanoic (formic) acid, which is responsible for the stings of ants and nettles.
Alcohols react with organic acids to form substances called as esters, which are found in all living organisms. Animal fats and vegetable oils are examples of such esters. Many esters are sweet-smelling chemicals which are widely distributed among fruits. It is these that give a fruit its characteristic smell and flavour. Many esters are manufactured for use as food flavourings, while others are used as solvents. Ethyl ethanoate (acetate) for example is made from ethanol and ethanoic acid and is a common solvent for paints, glues and nail varnish.
In the many different wines, while the main constituent remains the ethanol, it is the mixture of aldehydes and esters, carried through from the original fruits, that give each individual wine, even the most exotic, its own unique taste and aroma.
Thus, alcohol is not just a drink and does not only mark a celebration. It has various other uses too.