A conjugate acid–base pair is two species that differ only by a single proton (H⁺), one being the acid and the other its conjugate base. They are linked by the gain or loss of one proton. For example, NH₄⁺ and NH₃ form a conjugate pair, with NH₄⁺ the acid and NH₃ its conjugate base.

共轭酸碱对是仅相差一个质子(H⁺)的两种物质,其中一个是酸,另一个是它的共轭碱。它们通过得失一个质子而相联系。例如,NH₄⁺ 与 NH₃ 构成共轭对,NH₄⁺ 是酸,NH₃ 是它的共轭碱。