Equilibrium/equilibria Acid-base chemistry Buffers

The phenomena of reversible reactions and dynamic equilibria are widespread and relevant to many areas of chemistry. Consider, for instance, the whole field of acid-base chemistry (Chapters 8 and 18), where these ideas are crucial to our understanding of what an acid is, as well as to the use of indicators and buffers. In a similar way our conceptual grasp of electrochemistry is very much dependent on the interplay of reversible reactions (Chapter 19). We have commented earlier on how certain important industrial processes are dependent on some key reversible reactions. The ability to predict tbe effects of changes in physical conditions provided by Le Chatelier s principle is very useful indeed in establishing the best conditions to use for these processes. Such considerations help us to adapt conditions so as to maximize the yield of product. However, these are not the only considerations to be kept in mind. The rate at which a given yield is produced is also important economically, so the time taken to achieve a particular equilibrium is also of significance. Quite often these different considerations work in opposite directions and a compromise set of conditions is employed wbicb gives an acceptable yield in an economically viable time. 

You learned about acids and bases in your previous chemistry course. In this chapter, you will extend your knowledge to learn how the structure of a compound determines whether it is an acid or a base. You will use the equilibrium constant of the reaction of an acid or base with water to determine whether the acid or base is strong or weak. You will apply your understanding of dissociation and pH to investigate buffer solutions solutions that resist changes in pH. Finally, you will examine acid-base titrations that involve combinations of strong and weak acids and bases. 

Very many problems in solution chemistry are solved with use of the acid and base equilibrium equations. The uses of these equations in discussing the titration of weak acids and bases, the hydrolysis of salts, and the properties of buffered solutions are illustrated in the following sections of this chapter. 

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