History of acid-base concepts

It also has been known since antiquity that aqueous extracts of the ash 

Salt formation as a criterion for an acid-base interaction has a long history (Walden, 1929). Rudolph Glauber in 1648 stated that acids and alkalis were opposed to each other and that salts were composed of these two components. Otto Tachenius in 1666 considered that all salts could be broken into an acid and an alkali. Boyle (1661) and the founder of the phlogistic theory, Stahl, observed that when an acid reacts with an alkali the properties of both disappear and a new substance, a salt, is produced with a new set of properties. Rouelle in 1744 and 1754 and William Lewis in 1746 clearly defined a salt as a substance that is formed by the union of an acid and a base. 

It can be seen that these definitions are derived from experimental observation and are no more than classifications based on a set of properties shared by a group of substances. They are scientifically inadequate for the interpretation of results, which requires a definition based on concepts. Historically, the attempt to provide a model rather than a classification comes in the form of a search for imderlying universal principles. It seems that the alchemists recognized vague principles of acidity and alkalinity, and in the 17th century the iatrochemists made these the basis of chemical medicine. Disease was attributed to a predominance of one or other of these principles (Pattison Muir, 1883). 

Boyle (1661) attempted to provide a more definite concept and attributed the sour taste of acids to sharp-edged acid particles. Lemery, another supporter of the corpuscular theory of chemistry, had similar views and considered that acid-base reactions were the result of the penetration of sharp acid particles into porous bases (Walden, 1929 Finston Rychtman, 1982). However, the first widely accepted theory was that of Lavoisier who in 1 111 pronounced that oxygen was the universal acidifying principle (Crosland, 1973 Walden, 1929 Day Selbin, 1969 Finston Rychtman, 1982). An acid was defined as a compound of oxygen with a non-metal. 

The first substantial constitutive concept of acid and bases came only in 1887 when Arrhenius applied the theory of electrolytic dissociation to acids and bases. An acid was defined as a substance that dissociated to hydrogen ions and anions in water (Day Selbin, 1969). For the first time, a base was defined in terms other than that of an antiacid and was regarded as a substance that dissociated in water into hydroxyl ions and cations. The reaction between an acid and a base was simply the combination of hydrogen and hydroxyl ions to form water. 

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