Theory Bronsted

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. 

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 Lowry-Bronsted theory suffers from the following drawbacks (i) it explains the acidic or the basic nature of a substance only if a solvent such as water is present. In other words, molecules such as HC1, H2S04, etc. are not acids in the absence of water (ii) this concept fails to explain how acidic oxides (such as C02, S02, etc.) are neutralized by basic oxides (such as CaO, BaO) since there is no involvement of protons in these reactions, e.g. ... 

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 an acid is a proton donor. 

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 ... 

Bronsted theory See Bronsted-Lowry theory. bron-steth, the-3-re brown lead oxide See lead dioxide. braun led ak.sTd ... 

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... 

Nature often exploits large pJQ shifts in enzymes to effect chemical catalysis similarly, we hoped to apply the large shifts in the effective basicities of encapsulated guests to reaction chemistry. Initial studies focused on the hydrolysis of orthoformates, a class of molecules responsible for much ofthe formulation ofthe Bronsted theory of acids almost a century ago [98]. While orthoformates are readily hydrolyzed in acidic solution, they are exceedingly stable in neutral or basic solution [99]. However, in the presence of a catalytic amount of 1 in basic solution, small orthoformates are quickly hydrolyzed to the corresponding formate ester [38]. Addition of NEt4 to the reaction inhibited the catalysis but did not affect the hydrolysis rate measured in the absence of 1. With a limited volume in the cavity of 1, substantial size selectivity was observed in the orthoformate hydrolysis. Orthoformates smaller than tripentyl... 

For ionic solutions, ionic strength is an important parameter, affecting the quenching constant. The rate constant for bimolecular quenching collisions should be corrected to the limiting value k°q according to Bronsted theory... 

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. 

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. 

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

In 1923, J. N. Bronsted (1879-1947) and T. M. Lowry (1874-1936) independently The Bronsted-Lowry theory is presented logical extensions of the Arrhenius theory. Bronsted s contribution was more especially useful fur reactions in thorough than Lowry s, and the result is known as the Bronsted theory or the Bron- aqueous solutions. It is widely used in sted-Lowry theory. medicine and in the biological... 

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

---