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[14] [15] Lewis's proposal explains the Brønsted–Lowry classification using electronic structure. + + + In this representation both the base, B, and the conjugate base, A −, are shown carrying a lone pair of electrons and the proton, which is a Lewis acid, is transferred between them.
Johannes Nicolaus Brønsted and Martin Lowry introduced the Brønsted–Lowry theory, which said that any compound that can give a proton to another compound is an acid, and the compound that receives the proton is a base. A proton is a subatomic particle in the nucleus with a unit positive electrical charge.
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.
Bases are defined by the Brønsted–Lowry theory as chemical substances that can accept a proton, i.e., a hydrogen ion. In water this is equivalent to a hydronium ion). The Lewis theory instead defines a Base as an electron-pair donor. The Lewis definition is broader — all Brønsted–Lowry bases are also Lewis bases.
In acid catalysis and base catalysis, a chemical reaction is catalyzed by an acid or a base. By Brønsted–Lowry acid–base theory, the acid is the proton (hydrogen ion, H +) donor and the base is the proton acceptor. Typical reactions catalyzed by proton transfer are esterifications and aldol reactions.
In the above example, acetate is the base of the reverse reaction and hydronium ion is the acid. One hallmark of the Brønsted–Lowry theory in contrast to Arrhenius theory is that it does not require an acid to dissociate. The essence of Brønsted–Lowry theory is that an acid only exists as such in relation to a base, and vice versa.
A Lewis base is also a Brønsted–Lowry base, but a Lewis acid does not need to be a Brønsted–Lowry acid. The classification into hard and soft acids and bases ( HSAB theory ) followed in 1963. The strength of Lewis acid-base interactions, as measured by the standard enthalpy of formation of an adduct can be predicted by the Drago–Wayland ...
According to the Brønsted-Lowry theory of acids and bases, acids are proton donors and bases are proton acceptors. [4] An amphiprotic molecule (or ion) can either donate or accept a proton , thus acting either as an acid or a base .