An acid is a chemical, which when dissolved in water, gives a solution containing hydrogen ions. Acids turn blue litmus red, they react with certain metals to release hydrogen, they react with bases to form salts and they promote certain chemical reactions.
All acids taste sour. Fruits such as lemons taste sour because they contain citric acid. Vinegar is sour because it contains acetic acid.
There are two main chemical groups of acids. They are organic and inorganic acids. Organic acids contain carbon while inorganic acids don’t. Some examples of inorganic acids are hydrochloric acid, nitric acid and sulphuric acid. They are also called mineral acids and they are very strong. Formic acid, acetic acid, etc are organic acids. They are weaker acids.
Most of the organic acids are harmless. But inorganic acids can be dangerous as they can burn the skin. How do acids burn the body?
Inorganic acids have a strong tendency to absorb water and release a lot of heat in the process. Since most of the living cells contain water, strong acids like hydrochloric, sulphuric and nitric acid react with them and kill the cells, causing severe burns.
Acids are also essential for the body. Our stomachs contain hydrochloric acid to digest food. The stomach lining protects us from the acid, if the lining breaks; the acid can burn and cause an ulcer. Amino acids are essential for all kinds of life. Eight special amino acids are needed to stay alive.
Acids also have tremendous industrial importance. Millions of tons of sulphuric acid is made every year and used for many industrial purposes. It dissolves rust and scale deposited on iron. Acids are also used in making fertilizers, pigments, dyes, plastics and synthetics. Aquaregia, which is a mixture of nitric and hydrochloric acid, is used to dissolve gold and platinum.
Certain precautions are taken by people handling acids. They wear special clothes to protect their bodies’ from burns. Acids must always be poured slowly into water and never the other way round. If you are burnt by an acid, you should wash your skin with a lot of water, followed by a weak ammonia solution. If your eyes are affected, wash them immediately with water and then with sodium bicarbonate solution, which neutralizes any acid left.