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8.17: Brønsted-Lowry Acids and Bases: Introduction

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  • The previous eleven sections of this chapter have been devoted to the study of Arrhenius acids and Arrhenius bases, which are defined as proton, H+1, and hydroxide ion, OH–1, donors, respectively, in water.  In Sections 8.8, 8.9, and 8.11, three "shortcut" patterns were presented and applied for writing or identifying the chemical formulas of hydrohalogenated, "HX," and polyatomic, "HNPoly," Arrhenius acids and metal hydroxide Arrhenius bases, which are generically-symbolized as "M(OH)Y."  However, since the complete definitions of Arrhenius acids and bases were not utilized to develop these patterns, applying these symbolisms to classify a particular chemical as an Arrhenius acid or an Arrhenius base occasionally generates misleading or erroneous results, as exemplified by Exercise 8.12.2.  Therefore, the acid/base classifications that resulted from comparing these patterns to particular chemical formulas were independently-verified in Section 8.12, which presented and applied the process of writing solution equations for these chemicals and then comparing the generated symbolic information to the chemical and behavioral criteria that are established by the definitions of Arrhenius acids and Arrhenius bases.  Finally, because chemists are primarily interested in studying chemical changes, Sections 8.14, 8.15, and 8.16 presented generic reaction patterns that correspond to the transformations that occur when an Arrhenius acid reacts with an elemental metal, an Arrhenius base, and a metal carbonate or metal bicarbonate, respectively.  The patterns that were developed in these sections were subsequently applied to predict the products that are generated during specific chemical reactions.

    The remaining sections of this chapter will explore the applications of Brønsted-Lowry acid/base reactivity.  Recall that a Brønsted-Lowry acid is defined as a proton, H+1, donor in solution, and a Brønsted-Lowry base is defined as a proton, H+1, acceptor in solution.  In contrast to the aqueous solutions that Arrhenius studied, Brønsted and Lowry did not explicitly identify the solvent in which their solutes must be dissolved.  Consequently, these scientists were able to investigate the dissociative behaviors of chemicals that are not water-soluble and classified hundreds of molecules as Brønsted-Lowry acids or bases.  Because so many solutes can be categorized as Brønsted-Lowry chemicals, developing patterns for writing or identifying the formulas of Brønsted-Lowry acids and bases is highly impractical.  Therefore, the remaining sections of this chapter will not discuss the chemical formulas or names of individual Brønsted-Lowry chemicals.  Instead, these sections will explore the applications of Brønsted-Lowry acid/base reactivity, which involves the transfer of a proton, H+1, from a Brønsted-Lowry acid to a Brønsted-Lowry base.