Brpnsted, Johannes

Bromonium ion. See Halonium ion (R)- and (5)-2-Bromooctane, stereochemistry of hydrolysis of, 307—308, 319 A-Bromosuccinimide, reagent for allylic bromination, 371, 391 benzylic bromination, 415—416, 435 Brpnsted, Johannes, 134 Brpnsted acid. See Acidity Brpnsted base. See Basicity Brown, Herbert C., 228 Buckminsterfullerene, 410—411 1,3-Butadiene... 

A more general theory of acids and bases was devised independently by Johannes Br0n sted (Denmark) and Thomas M Lowry (England) m 1923 In the Brpnsted-Lowry approach an acid is a proton donor, and a base is a proton acceptor The reaction that occurs between an acid and a base is proton transfer... 

An important experimental rule for protolytic reactions was estabhshed by Johannes Nicolaus Brpnsted in 1918 (it was later extended to other reactions). He showed that for a series of reactions of the same type, the rate constants and the equilibrium constants are related simply as... 

The Danish chemist Johannes Brpnsted and the English chemist Thomas Lowry defined an acid as a proton (H ) donor, and a base as a proton (H ) acceptor. 

In 1923, two chemists working independently of each other, proposed a new theory of acids and bases. (See Figure 10.4.) Johannes Bronsted in Copenhagen, Denmark, and Thomas Lowry in London, England, proposed what is called the Brpnsted-Lowry theory of acids and bases. This theory overcame the problems related to the Arrhenius theory. 

In 1923, Johannes N. Brpnsted (1879-1947) and Thomas M. Lowry (1874-1936) independently defined acids and bases in a different way from the Arrhenins definitions. The resulting theory is sometimes called the Brpnsted-Lowry theory, bnt more often is referred to as just the Brpnsted theory. The Brpnsted theory extends the definitions of acid and base in a way that explains more than the Arrhenins definitions can explain. According to this theory, a Brpnsted acid is a proton donor, and a Brpnsted base is a proton acceptor. 

In 1923, the Danish chemist Johannes Brpnsted proposed a broader definition of acid. Surprisingly, the same year, the British scientist Thomas Lowry happened to make exactly the same proposal independently. Their idea was to apply the name acid to any species that can donate a proton. Recall that a proton is a hydrogen atom that has lost its electron it is a hydrogen ion and can be represented as Ht Such molecules or ions are now called Brunsted-Lowry acids. A reaction showing hydrochloric acid, a representative Brpnsted-Lowry acid, is depicted in Figure 7. 

The next theory of acids and bases is called the Brpnsted-Lowry Theory, proposed by Danish chemist Johannes Brpnsted and the English chemist Thomas Lowry, independently, in 1923. The definition of an acid, in this theory, sounds essentially the same as the Arrhenius acid. ABr0nsted-Lowry acid is defined as a substance that donates a proton to another species. Now, you might say, A proton is a hydrogen ion (H+), so what is the difference between the two definitions for acids Most notably, this definition doesn t require that the acid be in an aqueous solution. So a substance that donates protons, even when in a solid or vapor phase, is still acting as a Brpnsted-Lowry acid. 

Arrhenius s definitions of acids and bases are limited in that they apply only to aqueous solutions. Broader definitions were proposed by the Danish chemist Johannes Brpnsted in 1932 a Br0nsted acid is a proton donor, and a Br0nsted base is a proton acceptor. Note that Brpnsted s definitions do not require acids and bases to be in aqueous solution. 

In the early 20 century, the chemists Johannes Brpnsted and Thomas Lowry realized the proton-transfer nature of acid-base reactions. They defined an acid as a molecule (or ion) that donates a proton, and a base as a molecule (or ion) that accepts a proton. Therefore, in the aqueous reaction between strong acid and... 

Johannes Nicolaus Brpnsted (1879-1947). Danish chemist. In addition to his theory of acids and bases, Brbnsted worked on thermodynamics and the separation of mercury isotopes. In some texts, Brpnsted adds and bases are called Brpnsted-Lowry adds and bases. Thomas Martin Lowry (1874-1936). Enghsh chemist. Brpnsted and Lowry developed essentially the same add-base theory independently in 1923. 

Johannes Brpnsted and Thomas Lowry proposed a theory in which acids are defined as any hydrogen-containing substances capable of donating protons to other substances. Bases are substances that accept and form covalent bonds with protons. When a substance behaves as a Br0nsted acid by donating a proton, the substance becomes a conjugate base. 

Earlier in this chapter we considered Arrhenius s concept of acids and bases An acid is a substance that produces H+ ions when dissolved in water, and a base is a substance that produces OH ions. Although these ideas are fundamentally correct, it is convenient to have a more general definition of a base, which includes substances that do not contain OH ions. Such a definition was provided by Johannes N. Brpnsted (1879-1947) and Thomas M. Lowry (1874-1936), who defined acids and bases as follows ... 

Although the Arrhenius concept of acids and bases is useful, it is somewhat limited. For example, it tends to single out the OH ion as the source of base character, when other ions or molecules can play a similar role. In 1923, Johannes N. Brpnsted and Thomas M. Lowry independently noted that many reactions involve nothing more than the transfer of a proton (H ) between reactants, and they reaUzed that they could use this idea to expand the definitions of acids and bases to describe a large class of chemical reactions. In this view, acid—base reactions are proton-transfer reactions. 

In 1923 the Danish chemist Johannes N. Brpnsted (1879-1947) and, independently, the British chemist Thomas M. Lowry (1874-1936) pointed out that acid-base reactions can be seen as proton-transfer reactions and that acids and bases can be defined in terms of this proton (H ) transfer. According to the Br0nsted-Lowry concept, an acid is the species donating a proton in a proton-transfer reaction. A base is the species accepting the proton in a proton-transfer reaction. ... 

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