Acid-base theories development

Many chemical reactions are related to acids and bases. They are called acid/base reactions. In the course of time acids and bases have been described in different concepts. Today the Acid/Base Theory developed by Bronsted plays an essential role. 

The Arrhenius theory was the first modern acid-base theory developed. In this theory, an acid is a substance that, when dissolved in water, yields (Tiydro-gen) ions, and a base is a substance that, when dissolved in water, yields OH (hydroxide) ions. HCl(g) can be considered as a typical Arrhenius acid, because when this gas dissolves in water, it ionizes (forms ions) to give the ion. (Chapter 6 is where you need to go for the riveting details about ions.)... 

The addition of acid to the solution leads to shifts in the equilibria that favor the aqua-form of the complex. Thus, Pfeiffer, in 1906, established the reversible transformation of aqua-complexes into hydroxo-complexes. Werner later used this observation in the development of add-base concepts in coordination chemistry.32 Werner s work in this field is now largely of historical interest but two points, emphasized by Werner, remain espedally noteworthy, i.e. the importance of solvent in add-base equilibria and that bases may be considered as proton acceptors. These statements were incorporated into the acid-base theory developed by Bronsted and Lowry in 1923. 

This theory was a milestone in the development of acid-base concepts it was the first to define acids and bases in terms other than that of a reaction between them and the first to give quantitative descriptions. However, the theory of Arrhenius is far more narrow than both its predecessors and its successors and, indeed, it is the most restrictive of all acid-base theories. 

Lux (1939) developed an acid-base theory for oxide melts where the oxide ion plays an analogous but opposite role to that of the hydrogen ion in the Bronsted theory. A base is an oxide donor and an acid is an oxide acceptor (Lux, 1939 Flood Forland, 1947a,b Flood, Forland Roald, 1947) ... 

Acidity and basicity are paired concepts that are very often invoked to explain the catalytic properties of divided metal oxides and zeolites. The concept of acids and bases has been important since ancient times. It has been used to correlate large amounts of data and to predict trends. During the early development of acid-base theory, experimental observations included the sour taste of acids and the bitter taste of bases, color changes in indicators caused by acids and bases, and the reaction of acids with bases to form salts. 

In 1923, Johannes Br nsted and his English counterpart Thomas Lowry independently developed a more general acid-base theory. According to the Br nsted-Lowry model, an acid is a proton (H+) donor and a base is a proton acceptor. Each proton donor (acid) has its pair (conjugate) proton acceptor (base). In an acid-base reaction, H (proton) is transferred from an acid to a base. For example ... 

Today, when chemists use the words acid or base they refer to a model developed independently by Bronsted, Lowry, and Bjerrum. Since the most explicit statement of this theory was contained in the writings of Br /nsted, it is most commonly known as the Bronsted acid-base theory. 

Considerable progress in the development of theoretical and synthetic coordination and organometallic chemistry was made with the use of electron ideas. Lewis elaborated in 1923 the classic electron theory of acids and bases [30], and used it to explain the coordination ideas of Werner [31] (in Ref. 32, this achievement is ascribed to Sidgwick). A Lewis acid (A) is a acceptor of the electron pair and a Lewis base (B) is its donor [33], In other words, A is a species that can form a new covalent bond by accepting a pair of electrons and B is a species that can form a new covalent bond by donating a pair of electrons. The fundamental Lewis acid-base theory is described by a direct equlibrium [Scheme (1.1)], leading to the formation of the adduct (acid-base complex) ... 

Arrhenius acid-base theory - Arrhenius developed the theory of the electrolytic dissociation (1883-1887). According to him, an acid is a substance which delivers hydrogen ions to the solution. A base is a substance which delivers hydroxide ions to the solution. Accordingly, the neutralization reaction of an acid with a base is the formation of water and a salt. It is a so-called symmetrical definition because both, acids and bases must fulfill a constitutional criterion (presence of hydrogen or hydroxide) and a functional criterion (to deliver hydrogen ions or hydroxide ions). The theory could explain all of the known acids at that time and most of the bases, however, it could not explain the alkaline properties of substances like ammonia and it did not include the role of the solvent. -> Sorensen (1909) introduced the -> pH concept. 

Feb. 19,1859, Wijk, Sweden - Oct. 2,1927, Stockholm, Sweden). Arrhenius developed the theory of dissociation of electrolytes in solutions that was first formulated in his Ph.D. thesis in 1884 Recherches sur la conductibilit galvanique des dectrolytes (Investigations on the galvanic conductivity of electrolytes). The novelty of this theory was based on the assumption that some molecules can be split into ions in aqueous solutions. The - conductivity of the electrolyte solutions was explained by their ionic composition. In an extension of his ionic theory of electrolytes, Arrhenius proposed definitions for acids and bases as compounds that generate hydrogen ions and hydroxyl ions upon dissociation, respectively (- acid-base theories). For the theory of electrolytes Arrhenius was awarded the Nobel Prize for Chemistry in 1903 [i, ii]. He has popularized the theory of electrolyte dissociation with his textbook on electrochemistry [iv]. Arrhenius worked in the laboratories of -> Boltzmann, L.E., -> Kohlrausch, F.W.G.,- Ostwald, F.W. [v]. See also -> Arrhenius equation. 

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. 

Oct. 26, 1874, Bradford, West Riding, UK - Sep. 2, 1936, Cambridge, UK) Lowry is most well-known for his - acid-base theory that he developed independent... 

Lewis s research was wide-ranging and outstanding. He published important papers on chemical bonds, acid-base theory, and thermodynamics. He also developed firm ideas about howto build a chemistry department. His philosophy of education was something less than egalitarian. Writing in the Journal of Chemical Education, the distinguished chemist Gerald Branch spelled out Lewis s ideas "[F]or a chemist to be useful to... 

A third definition is based on the valance electron structures developed by Gilbert N. Lewis and does not involve the components of water. The Lewis definition states that substances that can accept electrons in an aqueous solution are acids, and substances that can donate electrons in an aqueous solution are bases. We will revisit Lewis s acid-based theory in Lesson 15, Acid and Bases. ... 

Our UNDERSTANDING OF THE REACTIONS of popular reagents dates back to the early 1920s, when Lewis, Lowry, and Br nsted began developing their acid-base theories. Shortly thereafter, Lap worth, who had pioneered the study of carbonyl addition reaction mechanisms in the early 1900s, proposed the classification of polar reagents into the classes we know today as electrophiles and nucleophiles. 

The concepts of acid-base equilibria were developed in this chapter for aqueous solutions (in aqueous solutions, water is the solvent and is intimately involved in the equilibria). However, the Bronsted-Lowry acid-base theory can be extended easily to other solvents. One such solvent that has been investigated in depth is liquid ammonia, NH3. 

One example of the development of a sedimentary structure has been worked out in Table 1 for the commonly present subject of acids and bases (De Vos Pilot, 2001). Several contexts followed each other over the years from Lavoisier, the ionic theories, the equilibrium theory, the Brpnsted-Lowry and Lewis theory, to contexts of our every day life and biochemical contexts. All these contexts are still being present in the contemporary curriculum. This confronts us with an incoherent acid-base theory, which is very difficult to learn and to teach, and even contains apparent inconsistencies between the layers of the sediment (see third column of the table). 

Clearly, the choice of the definition to be used will be dietated by the nature of the problem being investigated. For a diseussion of the historieal development of acid-base theory, see Bell [3] and Satchell and Satchell [4]. 

In 1923 Bronsted and Lowry each developed an acid-base theory based on the central role of the proton. They defined an acid as a proton donor and a base as a proton acceptor. Thus, an acid-base reaction is one in which proton transfer occurs, i.e.. 

The two clear, colorless gases mix, and a white solid of ammonium chloride forms. I show the intermediate formation of the ions in the equation so that you can better see what s actually happening. The HCl transfers an H to the ammonia. That s basically the same thing that happens in the HCl/NaOH reaction, but the reaction involving the ammonia can t be classified as an acid-base reaction, because it doesn t occur in water, and it doesn t involve the hydroxide ion. But again, the same basic process is taking place in both cases. In order to account for these similarities, a new acid-base theory was developed, the Bronsted-Lowery theory. 

In 1386, to build on the Greeks definition of sour or slippery, a new terminology was developed to speak about things that felt slippery. From the Arabic word al-qaliy, which means the ashes the term alkali was developed. This word was then used to speak about substances that felt slippery. Acid-base theory has been developed by scientists from around the world, and its vocabulary has been influenced by their languages. 

Johannes Nicolaus Brdnsted (1879-1947). Danish chemist. In addition to his theory of acids and bases, Br0nsted worked on thermodynamics and the separation of mercury into its isotopes. In some books. Brpnsted acids and bases are called Bronsted-Lowry acids and bases. Thomas Martin Lowry (1874—1936). English chemist. Brpnsted and Lowry developed essentially the same acid-base theory independently in 1923. 

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