Acids Bransted-Lowry definition

Acids are compounds that ionise to release hydrogen ions, or protons, to their surroundings. Bases are compounds that can accept hydrogen ions. This is called the Bransted-Lowry definition of acids and bases (named after yet another Scandinavian chemist, Johannes Nicolaus Bronsted, and Thomas Martin Lowry, who was British). There are other ways of explaining acidity and basicity, but the Bransted-Lowry theory works most of the time, and will be used throughout this book. 

We will consider more general definitions of acids and bases in Chapter 13 (Bransted-Lowry) and Chapter 15 (Lewis). 

A1C13, or S02 in an inert solvent cause colour changes in indicators similar to those produced by hydrochloric acid, and these changes are reversed by bases so that titrations can be carried out. Compounds of the type of BF3 are usually described as Lewis acids or electron acceptors. The Lewis bases (e.g. ammonia, pyridine) are virtually identical with the Bransted-Lowry bases. The great disadvantage of the Lewis definition of acids is that, unlike proton-transfer reactions, it is incapable of general quantitative treatment. 

We then learn the more general Bransted-Loivry definitions for acid and base. A Bronsted-Lowry acid is a proton donor and a Bronsted—Lowry base is a proton acceptor. 

Earlier in this chapter we considered Arrhenius s concept of acids and bases An acid is a substance that produces H+ ions when dissolved in water, and a base is a substance that produces OH- ions. Although these ideas are fundamentally correct, it is convenient to have a more general definition of a base, which covers substances that do not produce OH- ions. Such a definition was provided by Bransted and Lowry, who defined acids and bases as follows ... 

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