19.1 Acid-Base Theories

• Acids taste sour, bases taste bitter and feel slippery. Both are electrolytes and cause indicators to change colors.
• In an aqueous solution, an Arrhenius acid yields hydrogen ions and an Arrhenius base yields hydroxide ions.
• A Brønsted-Lowry acid is a hydrogen-ion donor; a Brønsted-Lowry base is a hydrogen-ion acceptor.
• A Lewis acid is an electron-pair acceptor; a Lewis base is an electron-pair donor.

19.2 Hydrogen Ions and Acidity

• For an aqueous solution, the product of [H⁺] and [OH⁻] equals 1 × 10⁻¹⁴
• On the pH scale, 0 is strongly acidic, 7 is neutral, and 14 is strongly basic.
• The acid and base form of an indicator have different colors in solution.

19.3 Strengths of Acids and Bases

• The stronger an acid is, the larger its K_a value.
• To find K_a of a weak acid or K_b of a weak base, substitute the concentrations of the substances into the equilibrium expression.

19.4 Neutralization Reactions

• An acid and a base react to produce a salt and water.
• The point of neutralization is the endpoint of a titration.

19.5 Salts in Solution

• Salts that produce acidic solutions contain positive ions that release protons to water; salts that produce basic solutions have negative ions that attract protons from water.
• A buffer is a solution of a weak acid or weak base and one of its salts.