Acids ionization in water

According to the Arrhenius definitions, an acid ionizes in water to produce protons (H" ) and a base produces hydroxide ions (HO ). The strength of an acid is given by its equilibrium constant for ionization in aqueous solution ... 

Some molecular compounds, like acids, ionize in water, forming ions. 

Acids are classified as strong or weak, depending upon their degree of ionization in water. A weak acid ionizes in water reversibly to form HjO ions. A weak acid is a weak electrolyte, and its aqueous solution does not conduct electricity well. The dissociation reaction occurs to a very small extent usually, fewer than 1 percent of the HA molecules are ionized. The ionization of a weak acid is shown as follows ... 

The correct answer is (A). This problem is an example of the common-ion effect. The weak acetic acid ionizes in water according to the following equation ... 

Water plays a different role here than in the formation of hydronium ions when acids ionize in water. Water molecules do not chemically react with this type of base. The hydroxide ion is formed by simple ionic dissociation, and no transfer occurs between the base and the water molecules to form the hydroxide ions. 

The molecular structure of a weak acid determines the extent to which the acid ionizes in water. Figure 14.14 shows the variety of structures of some common weak acids. 

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. 

Arrhenius acids ionize in water to give H" ions, and Arrhenius bases ionize in water to give OH ions. Brpnsted acids donate protons, and Brpnsted bases accept protons. 

Now suppose we add some oxalic acid (H2C2O4) to the original solution. Oxalic acid ionizes in water to form the oxalate ion, C2O4, which binds strongly to the Fe ions. The formation of the stable yellow ion Fe(C204)3 removes free Fe " ions in so-Intion. Consequently, more FeSCN units dissociate and the equilibrium shifts from left to right ... 

Many chemists, in fact, consider the product of acid ionization in water solution to be the hydronium ion and not the hydrogen ion. 

Boric acid ionizes in water in a similar fashion ... 

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