Acids Bronsted-Lowry concept

On the above basis it is, in principle, unnecessary to treat the strength of bases separately from acids, since any protolytic reaction involving an acid must also involve its conjugate base. The basic properties of ammonia and various amines in water are readily understood on the Bronsted-Lowry concept. 

The Bronsted-Lowry concept of acids and bases4 makes it unnecessary to distinguish between acid and base indicators emphasis is placed upon the charge types of the acid and alkaline forms of the indicator. The equilibrium between the acidic form InA and the basic form InB may be expressed as ... 

The base in the Bronsted-Lowry concept is any substance that can accept the proton it can even be the solvent. A Bronsted-Lowry base has an electron pair (a lone pair) that will accept the proton. The point that needs to be stressed here is that the proton is involved in both the definition of an acid (donates a proton) and a base (1accepts a proton). 

The Bronsted-Lowry concept looks at the equilibrium reaction and ties the acid on the left to a base on the right, called a conjugate acid-base pair or, more simply, a conjugate pair. Suppose we were to consider an acid reacting with a compound in equilibrium with the acid s anion and the products, as... 

Note that HA and B are not necessarily neutral. They could be ions that are capable of acting as an acid or a base. This is one of the features of the Bronsted-Lowry concept that broadens the definitions of acids and bases over the Arrhenius concept—there are many more substances that can behave as acids or bases. Further, we can write the reaction including the solvent, water in this case, and the associated Ka. 

Definition According to Bronsted-Lowry concept an acid is a molecule that can donate a proton and a base is a molecule that can accept that proton. 

The Bronsted-Lowry concept of acids and bases will be discussed in detail in Chapter 7. 

The Bronsted-Lowry concept describes many more processes as acid-base reactions than does the Arrhenius concept. For example, the ionization of hydrogen chloride gas as it dissolves in water, HC1 (g) — HC1 (aq), can be described as an acid-base process as the proton from HC1 is transferred to water. 

Clearly, ammonia is a Bronsted-Lowry base, it accepts a proton, but it is also a substance that forms hydroxide ion when dissolved in water, so it qualifies as an Arrhenius base too. The equation given earlier showing HC1 (aq) in water shows HCl(aq) to be an acid in both the Arrhenius and Bronsted-Lowry concepts. 

In terms of the Bronsted-Lowry concept, define an acid, a base and neutralization. 

Using words and a single chemical equation, show how nitric acid, HNO3(aq), is classed as an acid in both the Arrhenius and Bronsted-Lowry Concepts. 

Nitric acid ionizes in water to produce hydrogen ion, which exists in water as the hydronium ion. This makes it an Arrhenius acid. The equation showing the formation of the hydronium ion, H30+, shows nitric acid as a proton donor, making it an acid in the Bronsted-Lowry concept. 

Why is ammonia, NH3, considered to be a base in both in the Arrhenius and Bronsted-Lowry concepts of acids and bases ... 

In the Bronsted-Lowry concept, an acid is a proton donor, a base a proton acceptor and neutralization is the donation of one proton by an acid to a base. 

Bronsted-Lowry concept (14) An acid-base concept that defines an acid as a proton donor and a base as a proton acceptor. Neutralization is the transfer of a proton from an acid to a base. 

In terms of the Bronsted-Lowry concept of acids and bases, identify the acid, base, conjugate acid, and conjugate base in the following equation ... 

SECTION 16.2 The Bronsted- Lowry concept of acids and bases is more general than the Arrhenius concept and emphasizes the transfer of a proton (H ) fiom an acid to a base. The H ion, which is merely a proton with no surrounding valence electrons, is strongly bound to water. For this reason, the hydronium ion, H30" (flq), is often used to represent the predominant form of H in water instead of the simpler H"( q). 

SECTION 16.11 The Lewis concept of acids and bases emphasizes the shared electron pair rather than the proton. A Lewis acid is an electron-pair acceptor, and a Lewis base is an electron-pair donor. The Lewis concept is more general than the Bronsted Lowry concept because it can apply to cases in which the add is some substance other than H. ... 

Because the emphasis in the Bronsted-Lowry concept is on proton transfer, the concept also applies to reactions that do not occur in aqueous solution. In the reaction between gas phase HCl and NH3, for example, a proton is trcuisferred from the acid HCl to the base NH3 ... 

In the year 1923, two more theories defining acid-base character were proposed. The first theory, Bronsted and Lowry theory, is very satisfactory for understanding physiological processes and will therefore form the basis of all further discussions. The second theory, proposed by G. N. Lewis is much more general than the Bronsted - Lowry concept. A brief discussion of this theory is given in Box 1.1. 

The old definition of neutralization states that an acid and a base react with each other to form salt and water. The Bronsted-Lowry concept offers a much broader view of the process of neutralization. According to this concept, neutralization is a process of proton transfer from an acid to a base. Neutralization need not result in the formation of a recognizable salt and may not Involve water. 

BRONSTED-LOWRY CONCEPT OF ACID-BASE REACTIONS / 13.2... 

Bronsted-Lowry Concept of Acid-Base Reactions / 13.2 245... 

The Bronsted-Lowry theory focuses on the transfer of a proton from one species to another. However, the concepts of acids and bases have a much wider significance than the transfer of protons. Even more substances can be classified as acids or bases under the definitions developed by G. N. Lewis ... 

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. 

This concept covers most situations in the theory of AB cements. Cements based on aqueous solutions of phosphoric acid and poly(acrylic acid), and non-aqueous cements based on eugenol, alike fall within this definition. However, the theory does not, unfortunately, recognize salt formation as a criterion of an acid-base reaction, and the matrices of AB cements are conveniently described as salts. It is also uncertain whether it covers the metal oxide/metal halide or sulphate cements. Bare cations are not recognized as acids in the Bronsted-Lowry theory, but hydrated... 

When water acts as a Bronsted-Lowry acid, it donates a proton to another species, thereby converting to the hydroxide ion. HjO + H O OH + H3O" base acid conjugate conjugate base acid 1 point given for correct Bransted-Lowry concept of water being able to donate a proton, resulting in a hydroxide ion. 

Each of the three definitions expands our concept of acids and bases. Arrhenius basic definition is adequate for understanding many of the properties of acids and bases. It is important to recognize, though, that acids and bases are not fixed labels that can be applied to a substance. Bronsted-Lowry and Lewis showed that acid-base characteristics are dependent on the reactions that take place between substances. A... 

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