Bases percent ionization

In the box below, which has a volume of 0.50 L, the symbol represents 0.10 mol of a weak acid, HB. The symbol 9 represents 0.10 mol of the conjugate base, B . Hydronium ions and water molecules are not shown. What is the percent ionization of the acid ... 

Acids and bases are a big part of organic chemistry, but the emphasis is much different from what you may be familiar with from your general chemistry course. Most of the attention in general chemistry is given to numerical calculations pH, percent ionization, buffer problems, and so on. Some of this returns in organic chemistry, but mostly we are concerned with the roles that acids and bases play as reactants, products, and catalysts in chemical reactions. We ll start by reviewing some general ideas about acids and bases. 

Before continuing on to the last definition of acids and bases, it will be helpful to consider the definitions for strong and weak acids within the context of the Bronsted-Lowry model of acids and bases. The definitions are really an extension of the Arrhenius ideas. In the Arrhenius definitions, strong acids and bases were those that ionize completely. Most Bronsted-Lowry acids and bases do not completely ionize in solution, so the strengths are determined based on the degree of ionization in solution. For example, acetic acid, found in vinegar, is a weak acid that is only about 1 percent ionized in solution. That means that when acetic acid, HC2H302, is placed in water, the reaction looks like ... 

Wifii increasing dilution of the base, file hydroxide ion concentration decreases. However, because file concentration of file un-ionized base decreases more, file percent ionization increases. 

This exact solution (34 percent ionization) shows that the solution based on the original assumption was almost 25% too high. 

The extent to which a weak acid ionizes depends on the initial concentration of the acid. The more dilute the solution, the greater the percent ionization (Figure 15.4). In qualitative terms, when an acid is diluted, the number of particles (nonionized acid molecules plus ions) per unit volume is reduced. According to Le Chateher s principle (see Section 14.5), to counteract this stress (that is, the dilution), the equilibrium shifts from nonionized acid to H+ and its conjugate base to produce more particles (ions). The dependence of percent ionization on initial concentration can be illustrated by the HF case discussed on page 608 ... 

The strength of an acid or base is determined by the extent of its ionization in aqueous solution. Strong acids, such as hydrochloric acid, are 100 percent ionized in aqueous solution, whereas weak acids, such as acetic acid, are less than 5 percent ionized. Experimentally, the extent of ionization is determined by measuring the electrical conductance of solutions. Strong acids and bases are strong electrolytes, and weak acids and bases are weak... 

Compare the percent ionization of the base in Exercise 18a with the percent ionization of the base in Exercise 18d. Explain any differences. 

The first useful theory of acids and bases was proposed by Svante Arrhenius. His idea was that acids were substances which produced hydrogen ions, H", in aqueous solutions. Bases were substances which produced hydroxide ions, OH , when dissolved in water. Some acids and bases were found to be 100 percent ionized in solution, and were called strong acids or bases. Examples of strong acids are HCl and HNO3, which are completely ionized in aqueous solution to form and Cl and... 

Calculate the pH of a weak acid or weak base or its percent ionization given its concentration and K ot % (Sections 16.6 and 16.7)... 

Acid ionization constant Conjugate acid-base ( a). P-671 pair, p. 660 Base ionization constant Ion-product constant, p. 662 (K ), p. 678 Lewis acid, p. 697 Lewis base, p. 697 Strong acid, p. 666 Percent ionization, p. 677 Strong base, p. 667 pH, p. 663 Weak acid, p. 667 Salt hydrolysis, p. 689 Weak base, p. 668... 

The diagrams here show three weak acids FI A (A = X, Y, or Z) in solution, (a) Arrange the acids in order of increasing (b) Arrange the conjugate bases in increasing order of K, . (c) Calculate the percent ionization of each acid, (d) Which of the 0.1 M sodium salt solutions (NaX, NaY, or NaZ) has the lowest pFI (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.)... 

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