Br0nsted-Lowry Concept

In any solvent, the direction of the reaction always favors the formation of weaker acids or bases than the reactants. In the two examples above, H30 is a stronger acid than HNO2 and the amide ion is a stronger base than ammonia (and ammonium ion is a stronger acid than ammonia), so the reactions favor formation of HNO2 and ammonia. 

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Oxidation/reduction reactions can be viewed in a way that is analogous to the Br0nsted-Lowry concept of acid/base reactions (see Section 9A-2). Both involve... 

Recall that in the Br0nsted/Lowry concept, an acid/base reaction, is described by the equation... 

Strong base, //jO ion acts as the acid and OH ion acts as the base. Because it ionizes completely, a given amount of strong acid (or strong base) creates an equivalent amount of H30 (or OH ) when it dissolves in water. (We discuss the Br0nsted-Lowry concept thoroughly in Chapter 18.)... 

The Br0nsted-Lowry concept of acids and bases will be discussed in detail in Chapter 14. 

The Br0nsted-Lowry concept expands the definition of a base to encompass a host of species that the Arrhenius definition excludes to accept a proton, a base needs only a lone electron pair. 

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. ... 

You can also apply the Br0nsted-Lowry concept to the reaction of HCl and NH3 dissolved in benzene, CqHq, which was mentioned in the chapter opening. In benzene, HCl and NH3 are not ionized. The equation is... 

The Br0nsted—Lowry concept defines a species as an acid or a base according to its function in the acid—base, or proton-transfer, reaction. As you saw in Example 16.1, some species can act as either an add or a base. An amphiprotic species is a species that can act as either an acid or a base (it can lose or gain a proton), depending on the other reactant. For example, HC03 acts as an acid in the presence of OH but as a base in the presence of HF. Anions with ionizable hydrogens, such as HC03, and certain solvents, such as water, are amphiprotic. 

You have now seen several ways in which the Brpnsted-Lowry concept of acids and bases has greater scope than the Arrhenius concept. In the Br0nsted—Lowry concept... 

Certain reactions have the characteristics of acid—base reactions but do not fit the Br0nsted—Lowry concept. An example is the reaction of the basic oxide Na20 with the acidic oxide SO3 to give the salt Na2S04. ... 

The Br0nsted-Lowry concept considers an acid-base reaction as a proton-transfer reaction. It is useful to consider such acid—base reactions as a competition between species for protons. From Ihis point of view, you can order acids by Iheir relative... 

The Arrhenius concept was the first successful theory of acids and bases. Then in 1923, Br0nsted and Lowry characterized acid-base reactions as proton-transfer reactions. According to the Br0nsted—Lowry concept, an acid is a proton donor and a base is a proton acceptor. The Lewis concept is even more general than the Br0nsted-Lowry concept. A Lewis acid is an electron-pair acceptor and a Lewis base is an electron-pair donor. Reactions of acidic and basic oxides and the formation of complex ions, as well as proton-transfer reactions, can be described in terms of the Lewis concept. 

Describe four ways in which the Br0nsted-Lowry concept enlarges on the Arrhenius concept. 

A salt may be regarded as an ionic compound obtained by a neutralization reaction in aqueous solution. The resulting salt solution may be neutral, but often it is acidic or basic (Figure 17.8). One of the successes of the Br0nsted-Lowry concept of acids and bases was in pointing out that some ions can act as acids or bases. The acidity or basicity of a salt solution is explained in terms of the acidity or basicity of individual ions in the solution. 

Boyle s law the volume of a sample of gas at a given temperature varies inversely with the applied pressure. (5.2) Br0nsted-Lowry concept a concept of acids and bases in which an acid is the species donating a proton in a proton-transfer reaction, whereas a base is the species accepting a proton in such a reaction. (4.4 and 16.2)... 

The classical properties of adds and bases are listed in the introduction to the chapter. As an example of how a property relates to the ion associated with it, an acid-base neutralization is H+ + OH —> HjO. 3. An Arrhenius base is a source of OH ions, whereas a Br0nsted-Lowry base is a proton remover. The two are in agreement, as the OH ion is an excellent proton remover. Other substances, howeva-, can also remove protons, so there are other bases according to the Br0nsted-Lowry concept. 5. In the reaction shown below, AICI3, a Lewis add, accepts an electron pair from Q , a Lewis base, in a Lewis add—Lewis base neutralization reaction. 

We can write the formation of a hydrochloric acid solution as a transfer of from hydrogen chloride to water. By accepting H+ in the reaction, water is acting as a base according to the Br0nsted-Lowry concept. 

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