Acid-Base Chemistry of Water

A broad range of qualitative and quantitative concepts relating to aqueous acid-base chemistry are discussed. We first discuss the fact that much aquatic acid-base chemistry arises based on the properties of the H₂O molecule, which has the key features of being bent, polar, and amphoteric. We present a sequence of sections that discuss Brönsted-Lowry hydrogen ion transfer reactions, water autoionization, the pH scale, the behavior of strong and weak acids and bases, the behaviors of acidic and basic salts, the behavior of diprotic acids and bases, and buffered solutions. Furthermore, we discuss neutralization reactions and illustrate how they are the basis of volumetric analyses, i.e. acid-base titrations. In the discussion of titrations, some detail is given to the roles of (primary and secondary) standards and standardization and the properties and behavior of pH indicators. Most topics are first discussed qualitatively (with a review of key concepts, reactions, and equilibria) and then treated quantitatively with sample calculations. A special discussion is devoted to the indicator phenolphthalein, focusing on the way that the photophysical (light absorbance) properties of its various ionization structures depend on π-bonding conjugation in those structures.