Conjugate acid-base pair Two species

Conjugate acid-base pair two species related to each other by the donating and accepting of a single proton. (7.1) Conjugate base what remains of an acid molecule after a proton is lost. (7.1)... 

Conjugate acid-base pair two species in an acid-base reaction, one acid and one base, that differ by the loss or gain of a proton. (16.2)... 

The acetate ion is evidently a base. The acetic acid and the acetate ion are known as a conjugate acid-base pair. The term is applied generally to any two species related to each other as A is to B in the general equation. 

We can describe Bronsted-Lowry acid-base reactions in terms of conjugate acid-base pairs. These are two species that differ by a proton. In the preceding equation, HF (acid2) and (basc2) are one conjugate acid-base pair, and H2O (bascj) and H30 (acidj) are the other pair. The members of each conjugate pair are designated by the same numerical subscript. In the forward reaction, HF and H2O act as acid and base, respectively. In the reverse reaction, H30 acts as the acid, or proton donor, and F acts as the base, or proton acceptor. 

The following aqueous species constitute two conjugate acid-base pairs. Use them to write one acid-base reaction with A e > 1 and another with K < 1 HS, Cl, HCl, H2S. 

A conjugate acid-base pair consists of two species related to one another by the donating or accepting of a single proton, H. An acid has one more than its conjugate base a base has one less H+ than its conjugate acid. 

Within the Bronsted-Lowry model, certain pairs of molecules are described as a conjugate acid-base pair. The two species in a conjugate acid-base pair differ by a proton only. A base is said to have a conjugate acid, and an acid is said to have a conjugate base. 

BR0NSTED-LOWRY ACIDS AND BASES We learn that a Bnensted-Lowry acid is a proton donor and a Bnensted-Lowry base is a proton acceptor. Two species that differ by the presence or absence of a proton are known as a conjugate acid-base pair. 

Because free protons do not exist in solution, the above scheme is only a simplification. A complete acid-base reaction actually takes place when two systems, let them be Systems 1 and 2, of conjugate acid-base pairs interact with each other. If most of the species of system 1 are in the proton-rich (acidic) state, their acidity can be manifested only if most of the species in system 2 are in the proton-deficient (basic) state. During the course of their interaction, a proton is transferred from the acidic species of system 1, Ai, to the basic species of system 2, B2 ... 

H+ in acid-base reactions represents the proton and not the hydrogen ion, which exists in various solvents and, therefore, is of variable nature. In fact, because of its very high electron affinity, free proton as naked species does not exist in solution but is always attached to an electron pair. It follows that the ionization of an acid can occur only in the presence of a suitable base The proton is associated with either the acid itself or the solvent. The new species formed after the loss of the proton is referred to as the conjugate base of the acid It has an electron pair, can require a proton and, therefore, is a base. A more detailed description of all acid-base reactions, which include the ionization of acids in solution, can be given as in equation 3. Here HA, HB+ are acids, and B, A are bases HA, A and B, HB+ are two conjugate acid-base pairs. 

In the Bronsted-Lowry acid-base definition, a base is any species that accepts a proton therefore, there are many more Bronsted-Lowry bases than Arrhenius bases. When base B accepts a proton from acid HA, the species BH and A" form. HA and A" are a conjugate acid-base pair, as are BH and B. Thus, an acid-base reaction is a proton-transfer process between two conjugate acid-base pairs, with the stronger acid and base forming the weaker base and acid. (Section 18.3)... 

Check that each conjugate acid-base pair consists of one species from the left side of the equation and one species from the right side, and that the two species differ by only a proton. 

HCl donates a proton to water, producing the hydronium ion (HsO ) and the chloride ion (CF), which is the conjugate base of HCl. The two species, HCl and Cl , are known as a conjugate acid-base pair or simply a conjugate pair. Table 16.1 lists the conjugate bases of several familiar species. 

When CH3CCXDH loses a proton, it is converted into CHjCCX) . Notice that the formulas of these two species differ by a single proton, H. Species that differ by a single proton (H ) constitute a conjugate acid-base pair. Within this pair, the species with the added H is the acid, and the species without the H is the base. Thus, for reaction (16.1), we can identify two conjugate acid-base pairs. 

In the Bronsted-Lowry theory, an acid is a proton (H" ) donor and a base is proton acceptor. The deprotonated form of an acid is the corresponding conjugate base. The protonated form of a base is the corresponding conjugate acid. A quick way to identify the members of a conjugate acid-base pair is to identify two species that have molecular formulas that differ by a single H" ... 

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