We know that chemistry is the subject that deals with various substances, atoms, molecules and compounds. The first thing that strikes our minds on hearing the word chemistry is acids. We know that the subject chemistry also deals with the various chemical reactions, chemical compounds which are either acid or bases or salts. These are the substances that we come across in our day-to-day life activities. This article showcases a few basics and an introduction of acids.
What is an acid?
In general terms, acids are defined as any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance. Acids are sour substances. Acids is a chemical substance that is characterized by a sour taste in an aqueous medium. They have the tendency to turn blue litmus red. A few examples of acids are hydrochloric acid, sulphuric acid, acetic acid, benzoic acid, nitric acid, lactic acid and so on. All the acids have their own unique properties and applications. There are two main types of acids. They are organic acids and inorganic acids. Organic acids are not as strong as inorganic acids.
Theories of Acids
Scientists worked and researched all over the world to find the properties of acids. Some researchers have given their own theories and definition of acids. The term acid has been defined in various ways, depending on the particular way of looking at the properties of acidity and basicity. Some of them are listed below:
Robert Boyle
The scientist Robert Boyle, defined acid as a substance that has a sour taste and is corrosive. It is a chemical that changes the colour of certain vegetable dyes, such as litmus.
Arrhenius Theory
Arrhenius proposed that acid is a substance that ionizes in water to give H+ ions. He says an acid generates H+ ions in a solution, whereas a base produces an OH– ion in its solution.
Bronsted-Lowry Theory
According to Bronsted-Lowry theory, acid is a substance that donates an H+ ion or a proton and forms its conjugate base. The Bronsted-Lowry acid is a substance that donates a proton or H+ ion to the other compound.
Lewis Theory
Lewis Acids are chemical substances that have empty orbitals and are able to accept electron pairs from Lewis bases. This term was used to describe chemical species with a trigonal planar structure and an empty p-orbital. The species that can accept electron pairs are acids and called Lewis acids.
Properties of Acids
Acids have some unique properties. Few properties of acid are listed below
- On a general note, acids are corrosive in nature.
- Acids are sour-tasting substances.
- Acids are good conductors of electricity.
- The pH values of acids are always less than 7.
- Acids reacting with metals produce hydrogen gas.
- Mineral acids are colourless.
- Acids are soluble in the universal solvent that is water.
- Acids turn blue litmus paper into a red colour.
Applications of Acids
We come across the application of acid in various fields. Some acids are used in our daily activities. The majority of acids are used in factories and industries in preparation for many other compounds and purification purposes. For instance the farmers use boric acid as a fungicide and also as an insecticide powder. It is used to prepare buffer solutions in industries and laboratories.
Listed below are a few applications of acids:
- Hydrochloric acid is used in the production of oil in industries. It is also used in the refining of cane sugar.
- Sulphuric acid is considered as a strong acid and is mainly used in the purification of gasoline in industries other refinery products. Sulfuric acid is used in processing metals and other metallurgical processes. It is widely used in batteries as well.
- Benzoic acid is used in many cosmetic products such as lipsticks and gloss.
- Acetic acid is majorly used in disinfecting, cleaning and in the preservation of a few food items such as pickles and jams.
- Nitric acid is used in the industrial production of explosives, dyes, paints, and fertilizers.
- Citric acid is present in citrus fruits such as lemon, oranges which are used in the preparation of food.
Likewise, there are wide applications of various other acids in manufacturers of soaps, detergents, oil refineries, preparations of salt compounds and also acts as cleansing agents. Acids are the most popular chemicals with unique characteristics and a wide range of applications in all areas.
