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In chemistry, an acid–base reaction is a chemical reaction that occurs between an acid and a base.It can be used to determine pH via titration.Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their application in solving related problems; these are called the acid–base theories, for example, Brønsted–Lowry acid–base theory.
Amphoteric is derived from the Greek word amphoteroi (ἀμφότεροι) meaning "both".Related words in acid-base chemistry are amphichromatic and amphichroic, both describing substances such as acid-base indicators which give one colour on reaction with an acid and another colour on reaction with a base.
[15] In Lewis theory an acid, A, and a base, B, form an adduct, AB, where the electron pair forms a dative covalent bond between A and B. This is shown when the adduct H 3 N−BF 3 forms from ammonia and boron trifluoride , a reaction that cannot occur in water because boron trifluoride hydrolizes in water.
Three different points in an acid-base titration using phenolphthalein as the indicator. Phenolphthalein is widely recognized as one of the most commonly used acid-base indicators in chemistry. [12] Its popularity is because of its effectiveness in a broad pH range and its distinct colour transitions. [12]
According to the original formulation of Lewis, when a neutral base forms a bond with a neutral acid, a condition of electric stress occurs. [7] The acid and the base share the electron pair that formerly belonged to the base. [7] As a result, a high dipole moment is created, which can only be decreased to zero by rearranging the molecules. [7]
The E and C parameters refer, respectively, to the electrostatic and covalent contributions to the strength of the bonds that the acid and base will form. The equation is -ΔH = E A E B + C A C B + W. The W term represents a constant energy contribution for acid–base reaction such as the cleavage of a dimeric acid or base. The equation ...
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For example, if the concentration of the conjugate base is 10 times greater than the concentration of the acid, their ratio is 10:1, and consequently the pH is pK a + 1 or pK b + 1. Conversely, if a 10-fold excess of the acid occurs with respect to the base, the ratio is 1:10 and the pH is pK a − 1 or pK b − 1.