Many acids and bases occur naturally in nature, such as citric acid in fruits like orange, lemon etc, tartaric acid in tamarind, malic acid in apples and lactic acid in milk and milk products, hydrochloric acid in gastric juices. Similarly, many bases are found such as lime water. We use many of these acids in our day to day life, such as vinegar or acetic acid in the kitchen, boric acid for laundry, baking soda for the purpose of cooking, washing soda for cleaning etc.
Many of the acids that we do not consume in the household are used in the laboratories and industries, which include an acid such as HCl, H2SO4 etc. and bases such as NaOH, KOH etc. When these acids and bases are mixed in the right proportions, the neutralization reaction thus results in the formation of salt and water. Some naturally occurring salts found in nature include NaCl and KCl etc in seawater and natural rock deposits. In this section, we will read more about acid, base and salt and their properties.
The term acid is derived from a Latin word ‘acidus’ or ‘acere’, which means sour. The most common characteristic is their sour taste. An acid is a substance that renders ionizable hydronium ion (H3O+) in its aqueous solution. It turns blue litmus paper red. These dissociate in their aqueous solution to form their constituent ions, as given by the following examples.
Based on their occurrence, they are divided into two types- Natural and mineral acids.
Natural Acids: These are obtained from natural sources, such as fruits and animal products. For e.g. lactic, citric, and tartaric acid etc.
Mineral Acids: Mineral acids are acids prepared from minerals. For example, Hydrochloric acid (HCl), Sulphuric Acid (H2SO4), and nitric acid (HNO3) etc.
The most common characteristic of bases is their bitter taste and soapy feel. A base is a substance that renders hydroxyl ion(OH–) in their aqueous solution. Bases turn the colour of red litmus paper to blue.
The bases dissociate in their aqueous solution to form their constituent ions, given by the following examples.
Salt is an ionic compound that results from the neutralization reaction of acids and bases. Salts are constituted of positively charged ions, known as cations and negatively charged ions, known as anions, which can either be organic or inorganic in nature. These ions are present in a relative amount, thus rendering the nature of the salt neutral.
The formation of salt can be seen from the chemical reactions shown in the equations below.