Acid-base reactions are important in biochemistry, technology and industry. They can be used to regenerate starting materials. They can also be used to determine the pH of a solution by titration. It is a reversible process. Normally, most acid-base reactions occur in aqueous solutions. If an acid is added to a base, the acid will react with the base to produce water and a salt.
In the early days of chemical classification, substances were classified as acids or bases based on their general properties. Acids were considered corrosive and sour while bases were characterized as neutral.
Later chemists refined their classifications. They determined that an acid is a substance that gives off hydrogen ions. A base is a substance that accepts a proton. An acid can be either strong or weak, while a base has a range of pH values. Strong acids are usually between 0 and 1, while strong bases are between 13 and 14.
The first modern definition of acids and bases was developed by Svante Arrhenius. He derived his theory on the basis of the observation that both acids and bases dissociate in water. His theory defines acids as aqueous compounds that give off hydrogen ions. Bases are also aqueous compounds that accept a proton.
The concept of acids and bases was later elaborated by the Lewis and Bronsted-Lowry models. Both theories use the same concept, but they differ in the way they describe the mechanisms involved. For instance, the Bronsted-Lowry model defines acids as proton acceptors, while the Lewis model focuses on electron lone pairs.