Acids and bases are important classes of chemical compounds. They are part of the foods and beverages we ingest, they are present in medicines and other consumer products, and they are prevalent in the world around us. In this chapter, we will focus on acids and bases and their chemistry. 12.1: Introduction Certain household chemicals, such as some brands of cleanser, can be very concentrated bases, which makes them among the most potentially hazardous substances found around the home; if spilled on the skin, the strong caustic compound can immediately remove H+ ions from the flesh, resulting in chemical burns. Compare that to the fact that we occasionally purposefully ingest substances such as citrus fruits, vinegar, and wine-all of which contain acids. 12.2: Arrhenius Acids and Bases An Arrhenius acid is a compound that increases the H+ ion concentration in aqueous solution. An Arrhenius base is a compound that increases the OH− ion concentration in aqueous solution. The reaction between an Arrhenius acid and an Arrhenius base is called neutralization and results in the formation of water and a salt. 12.3: Brønsted-Lowry Acids and Bases A Brønsted-Lowry acid is a proton donor; a Brønsted-Lowry base is a proton acceptor. Acid-base reactions include two sets of conjugate acid-base pairs. 12.4: Autoionization of Water In any aqueous solution at room temperature, the product of \([H^+]\) and \([OH^−]\) equals \(1.0 \times 10^{−14}\). 12.5: The pH Scale pH is a logarithmic function of [H+]. [H+] can be calculated directly from pH. pOH is related to pH and can be easily calculated from pH. 12.6: Acid-Base Titrations A titration is the quantitative reaction of an acid and a base. Indicators are used to show that all the analyte has reacted with the titrant. 12.7: Strong and Weak Acids and Bases and their Salts Strong acids and bases are 100% ionized in aqueous solution. Weak acids and bases are less than 100% ionized in aqueous solution. Salts of weak acids or bases can affect the acidity or basicity of their aqueous solutions. 12.8: Buffers A buffer is a solution that resists sudden changes in pH. 12.9: Acids and Bases (Exercises)