Theories of acids and bases - a set of fundamental physicochemical concepts that describe the nature and properties of acids and bases. All of them introduce definitions of acids and bases - two classes of substances that react with each other. The goal of the theory is to predict the reaction products between the acid and the base and the possibility of its occurrence, for which quantitative characteristics of the strength of the acid and base are used. Acids and bases manifest their properties only in the presence of each other. Not a single thing will give off a proton if there is no proton acceptor in the system — a base, and vice versa. they form a conjugated acid-base pair in which the stronger the acid, the weaker the base conjugated to it, and the stronger the base, the weaker the acid conjugated to it.