Ácidobase

Ácidobase is a term used in chemistry to describe the study of acids and bases and the reactions in which they participate. It encompasses several theoretical frameworks that explain how acids donate protons, how bases accept them, and how electron pairs relate to acid–base behavior.

The most common theories are Arrhenius, Brønsted–Lowry, and Lewis. Arrhenius defines acids as substances that increase H+ in water and bases as substances that increase OH− in water. Brønsted–Lowry generalizes this to acids as proton donors and bases as proton acceptors, regardless of the solvent. The Lewis definition broadens acidity and basicity to include electron-pair acceptors and donors, enabling the description of many nonprotic reactions.

Key concepts include pH, a measure of hydrogen ion activity, and the pH scale, typically spanning 0 to 14 at 25°C. Acid strength refers to the tendency of an acid to donate a proton, while base strength refers to the tendency of a base to accept one. Strong acids and bases dissociate nearly completely in water; weak ones do not. Conjugate acid–base pairs are related species formed by proton transfer.

Buffers are solutions that resist pH change, often described by the Henderson–Hasselbalch equation. Common examples include acetic acid/acetate and the bicarbonate buffering system in blood. Important applications span chemistry, biology, medicine, and environmental science. Limitations arise in non-aqueous solvents where pH is not defined the same way, and different solvent systems can shift acid–base behavior.

Examples: hydrochloric acid (strong acid), acetic acid (weak acid), ammonia (weak base), sodium hydroxide (strong base). Understanding ácido-base chemistry enables predictions of reaction outcomes, pH control, and the design of buffering systems.