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Cover Making the Transition to University Chemistry

Acid–base Equilibrium  

This chapter explains the acid-base equilibrium. This involves the transfer of protons in line with the Brønsted–Lowry theory. A strong acid or strong base is fully ionized in an aqueous solution, while weak acids or bases are only partially ionized in an aqueous solution. Acid-base titrations measure the unknown concentration of one solution by reaction with another standard solution with a familiar concentration. The chapter also notes how indicators are typically water-soluble weak organic acids with varying colours at different pH values. It explores the alternative theory of acid-base reactions proposed by Gilbert Lewis: a Lewis acid is an electron-pair acceptor, while a Lewis base is an electron-pair donor.


Cover Foundations of Organic Chemistry

Acids and bases  

This chapter examines acids and bases. The Brønsted–Lowry theory states that acids are proton donors, and bases are proton acceptors. Acid/base reactions are largely equilibria and are therefore under thermodynamic control. Many organic acids, such as ethanoic acid, are weak acids. The equilibrium constants are small, much less than 1, and remarkably little of the acid donates its proton to water in aqueous solution. Moreover, many organic acids and bases are largely insoluble in water. The chapter then considers the reactivity of bases as leaving groups and nucleophiles, before comparing acid strengths and base strengths. It also looks at amino acids, which are the building blocks of proteins; they are compounds which have major structural and catalytic roles in all living organisms.


Cover Aqueous Acid-Base Equilibria and Titrations

Basic concepts  

This chapter discusses the basic concepts of acids, bases, and pH. The concept of acid and base can be generalized in several ways. The book uses the definition given by Brönsted, which emphasizes the complementary nature of acids and bases in aqueous solutions. It considers as an acid any substance that can donate a proton, and as a base any proton acceptor. In this nomenclature, an acid that loses its proton become a base, and vice versa, so that one can consider conjugate acid-base pairs. Meanwhile, the concept of pH was introduced by Sørensen as the negative logarithm of the hydrogen concentration. The chapter then looks at the mass action law, which is the fundamental law of chemical equilibrium. It also considers concentration fractions, logarithmic concentration diagrams, and the proton condition.