Bases Bronsted theory

Backbone (protein), 1028 Backside displacement. reaction and.363-364 von Baeyer, Adolf, 113 Baeyer strain theory, 113-114 Bakelile, structure of, 1218 Banana, esters in, 808 Barton, Derek, H. R., 389 Basal metabolic rate, 1169 Basal metabolism. 1169-1170 Base, Bronsted-Lowry, 49 Lewis, 57, 59-60 organic, 56-57 strengths of, 50-52 Base pair (DNA), 1103-1105 electrostatic potential maps of. 

Barrier-layer cells 658 Baryta see Barium hydroxide Bases. Bronsted-Lowry theory of, 21 dissociation constants of, (T) 833 hard, 54 ionisation of, 21... 

A note on good practice The entities that are regarded as acids and bases are different in each theory. In the Lewis theory, the proton is an acid in the Bronsted theory, the species that supplies the proton is the acid. In both the Lewis and Bronsted theories, the species that accepts a proton is a base in the Arrhenius theory, the species that supplies the proton acceptor is the base (Fig. 10.61. 

Since Arrhenius, definitions have extended the scope of what we mean by acids and bases. These theories include the proton transfer definition of Bronsted-Lowry (Bronsted, 1923 Lowry, 1923a,b), the solvent system concept (Day Selbin, 1969), the Lux-Flood theory for oxide melts, the electron pair donor and acceptor definition of Lewis (1923, 1938) and the broad theory of Usanovich (1939). These theories are described in more detail below. 

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) ... 

Thus an acid-base reaction involves the transfer of an oxide ion (compared with the transfer of a proton in the Bronsted theory) and the theory is particularly applicable in considering acid-base relationships in oxide, silicate and aluminosilicate glasses. However, we shall find that it is subsumed within the Lewis definition. 

Any text on acids and bases would not be deemed complete if mention were not made of the extended definition of acids and bases that is embodied in the Lowry-Bronsted theory. The theory basically proposed a more general definition of acids and bases to overpower the limitations of the theory arising from the Arrhenius concept. 

The Br0nsted theory expands the definition of acids and bases to allow us to explain much more of solution chemistry. For example, the Brpnsted theory allows us to explain why a solution of ammonium chloride tests acidic and a solution of sodium acetate tests basic. Most of the substances that we consider acids in the Arrhenius theory are also acids in the Bronsted theory, and the same is true of bases. In both theories, strong acids are those that react completely with water to form ions. Weak acids ionize only slightly. We can now explain this partial ionization as an equilibrium reaction of the ions, the weak acid, and the water. A similar statement can be made about weak bases ... 

In the Bronsted theory, an acid is defined as a substance that donates a proton to another substance. In this sense, a proton is a hydrogen atom that has lost its electron it has nothing to do with the protons in the nuclei of other atoms. (The nuclei of 2H are also considered protons they are also hydrogen ions.) A base is a substance that accepts a proton from another substance. The reaction of an acid and a base produces another acid and base. The following reaction is thus an acid-base reaction according to Bronsted ... 

Identify each of the following terms (a) hydronium ion, (h) Bronsted theory, (c) proton (Bronsted sense), (d) acid (Bronsted sense), (e) base (Bronstcd sense), (/) conjugate, (g) strong, (h) acid dissociation constant, (/) ionization constant, (/) base dissociation constant, (k) autoionization, (/) pH, and f/w) K .. 

Bronsted theory a theory of acids and bases that defines acids as proton donors and bases as proton acceptors. 

The Lowry-Bronsted theory says a base is a proton remover. 

The concepts of the Lowry-Bronsted theory may explain the various reactions that take place during many non-aqueous titrations. Thus, an acid is a proton donor and a base is a proton acceptor. Therefore, when an acid HA undergoes dissociation it gives rise to a proton and the conjugate base A of the acid ... 

Brensted-Lowry theory chem A theory that all acid-base reactions consist simply of the transfer of a proton from one base to another. Also known as Bronsted theory. ( jbran steth lau re, the-3-re ... 

With reference to a solvent, this term is usually restricted to Brpnsted acids. If the solvent is water, the pH value of the solution is a good measure of the proton-donating ability of the solvent, provided that the concentration of the solute is not too high. For concentrated solutions or for mixtures of solvents, the acidity of the solvent is best indicated by use of an acidity function. See Degree of Dissociation Henderson-Hasselbalch Equation Acid-Base Equilibrium Constants Bronsted Theory Lewis Acid Acidity Function Leveling Effect... 

Conjugate Acid in the Bronsted theory, the substance formed when a base accepts a proton... 

Conjugate Acid-Base Pair in the Bronsted theory, an acid and its conjugate base or a base and its conjugate acid Conjugate Base in the Bronsted theory, the substance that remains when an acid donates a proton... 

Applying the Concept of Conjugation to the Bronsted Theory of Acid-Base... 

The Lewis theory does not differ from Bronsted theory with respect to substances classified as bases. A substance capable of donating an electron pair (i.e., any Lewis base) is capable of donating electron pair to a proton. Being proton acceptor it is also a Bronsted base. Thus both definitions label the following as... 

Acid and Base Catalysis. Opportunities are now available for checking some of the theories of acids and bases which involve both the manner of readjustment within the molecule and the function of the catalyst. An acid dissociates according to the Bronsted theory to give a proton and a base. The rate of a given change will be faster for a proton than for a deuton but there will be little differ-... 

In his later studies Hantzsch assumed, according to the Bronsted theory of acids and bases, that nitric acid acts as a base towards sulphuric acid. According to Bronsted, an acid is a compound able to give off a proton while a base is a compound able to take up a proton. 

Usanovich [20] and Lewis [20a] have generalized the Bronsted theory. The latter considered adds to be compounds which are able to employ a lone pair of electrons from another molecule bases are compounds having a lone pair of electrons which may be used by another molecule. 

According to the Bronsted theory ammonia behaves in this case like a base, capable to accept a proton from the acid (water) and to transform itself into a conjugated acid NHj. 

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. 

Bronsted-Lowry theory of acids and bases the theory defining an acid as a substance from which a hydrogen ion can be removed and a base as a substance that can remove a hydrogen ion from an acid (10.1)... 

The Bronsted theory of acids and bases defines an acid as a proton donor and a base as a proton acceptor, i.e. a pro tic acid such as hydrochloric acid is a source of protons. Although the idea of an acidic hydrogen in organic compounds may initially be understood in terms of a carboxyl hydroxyl group, a hydrogen atom may become weakly acidic in a number of other circumstances, e.g. when it is attached to a carbon atom that is adjacent to a carbonyl group. On the other hand, a base such as an amine, or a carboxylate anion, is capable of accepting a proton. 

In a wider interpretation of the nature of acids and bases (Bronsted-Lowry Theory), HA and A are said to be conjugate they form a conjugate acid-base pair. Here, HA is the conjugate acid of A , and A is the conjugate base of HA. 

According to the Lowry-Bronsted theory of acids and bases, an acid is a substance which... 

The Bronsted Theory Acid-Base Equilibrium Autoionization of Water pH... 

An important feature of the Bronsted theory is the relationship it creates between acids and bases. Every Bronsted acid has a conjugate base, and vice versa. 

Whereas the Lewis acid-base theory does not contradict Bronsted theory, as "bases" in Bronsted theory must have a pair of nonbonding electrons in order to accept a proton, it expands the family of compounds that can be called "acids" any compound that has one or more empty valence-shell orbital and provides an explanation for the instantaneous reaction of boron triflouride (BF3) with ammonia (NH3). The nonbonding electrons on the nitrogen in NH3 are donated into an empty orbital on the boron to form a new covalent bond, as shown in Eq. 13. 

The Bronsted theory designates water as an acid in its reactions with bases and as a base in its reactions with acids. Thus it should not be too surprising that water can react with itself, acting both as... 

Carbon dioxide reacts with the hydroxide ion to produce the bicarbonate anion. Write the Lewis dot structures for each reactant and product. Label each as a Bronsted acid or base. Explain the reaction using the Bronsted theory. Why would the Arrhenius theory provide an inadequate description of this reaction ... 

The Bronsted theory states that the acid/base character of a compound depends on its reaction partner and is therefore not an absolute. An indication that transition metal compounds can act as bases is provided by the long-known protonation reactions of transition metal complexes, generally of low oxidation state. An example is cobalt carbonyl hydride, the true catalyst in many carbonylation reactions ... 

The advantage of the Bronsted theory is that the formation of acids and bases occurs via protolysis reactions including the corresponding acids and bases. The dissociation degree a describes the position of the equilibrium (4.164) and therefore the acid strength. ... 

In the Lowry-Bronsted theory of acids and bases (1923), the definition was extended to one in which an acid is a proton donor, and abase is a proton acceptor. For example, in... 

The original Arrhenius definition of a base has been extended by the Lowry-Bronsted theory and by the Lewis theory. See acid. 

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