Bases, chemical Lowry-Bronsted theory

The limitations of the Arrhenius theory of acids and bases are overcome by a more general theory, called the Bronsted-Lowry theory. This theory was proposed independently, in 1923, by Johannes Br0nsted, a Danish chemist, and Thomas Lowry, an English chemist. It recognizes an acid-base reaction as a chemical equilibrium, having both a forward reaction and a reverse reaction that involve the transfer of a proton. The Bronsted-Lowry theory defines acids and bases as follows ... 

The Lewis theory of acids and bases is more general than Bronsted-Lowry theory, but Bronsted-Lowry s definition is used more frequently. The terms "acid" and "base" most often refer to Bronsted acids and bases, and the term "Lewis acid" is usually reserved for chemicals like BF3 that are not Bronsted acids. 

Feb. 22,1879, Varde, Denmark - Dec. 17,1947, Copenhagen, Denmark) Ph.D. Copenhagen 1908, since 1908 Professor of Chemistry (the 3rd chair, i.e., the chair of Physical Chemistry at the Univ. of Copenhagen). 1926/27 visiting Professor at Yale Univ., New Haven, Connecticut, USA. Famous for his work on chemical reaction kinetics, chemical affinity, indicators, and thermodynamics of solutions. He could explain the effect of activity coefficients on reaction rates in solutions. In 1923 he developed independently of - Lowry, and - Bjerrum a new -> acid-base theory, the so-called Bronsted acid-base theory. 

Many organic and biological reactions are acid-base reactions that do not lit within the Arrhenius or Bronsted-Lowry theories. Experienced chemists find the Lewis theory to be very usefol because so many other chemical reactions are covered by it. The less experienced sometimes find the theory less useful, but as their knowledge expands so does its utility. 

Perhaps you will not be surprised, then, you to learn that an even more general model of acids and bases was proposed by American chemist G. N. Lewis (1875-1946). Recall that Lewis developed the electron-pair theory of chemical bonding and introduced Lewis structures to keep track of the electrons in atoms and molecules. He applied his electron-pair theory of chemical bonding to acid-base reactions. Lewis proposed that an acid is an ion or molecule with a vacant atomic orbital that can accept (share) an electron pair. A base is an ion or molecule with a lone electron pair that it can donate (share). According to the Lewis model, a Lewis acid is an electron-pair acceptor and a Lewis base is an electron-pair donor. Note that the Lewis model includes all the substances classified as Bronsted-Lowry acids and bases and many more. 

The ability of certain chemical compounds to lose or gain protons has been an active area of research since the formulation the concept of pH in 1909 [1] and the appearance of the Bronsted-Lowry acid-base theory in 1923. According to Bron-sted and Lowry an acid is a compound that can donate a proton, whereas a base is a compound that can accept a proton. The dissociation of a proton from an acid in solution can be modeled by a simple equilibrium constant... 

There are various definitions of acids and bases. The one used here is attributed to a theory developed in 1923 independently by Johannes Bronsted (1879-1947), a Danish chemist, and Thomas Lowry (1874-1936), a British chemist. Recall that an atom of ordinary hydrogen has only a proton and an electron, and no neutrons. Therefore, a cation of ordinary hydrogen (H+) is just a proton. In the Bronsted-Lowry definition of acids and bases, an acid is a proton donor, that is, it can react with other compounds or ions by transferring one or more ions to the other compounds or ions. A base is a proton acceptor It can react with the H+ ions of compounds or ions that are acids. Some chemical species, such as H O, are said to be amphiprotic, that is, they are both donors and acceptors of protons they are both an acid and a base. These definitions are illustrated in the following examples ( aq means the reaction is taking place in aqueous solution) ... 

The acid-base concept, either in the limited interpretation of the Bronsted-Lowry theory or in the more general sense of the Lewis theory, is one of the most useful classification schemes in chemistry and a tool for systematizing the relationship between structure and reactivity. In this section we examine how this general concept can be applied to solid surfaces [29], From the most general (Lewis) point of view, a surface is classified as acidic (electron acceptor) or basic (electron donor) according to the direction of net electron transfer that results in the formation of new chemical bonds with an adsorbed molecule. 

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