What Characterizes a Strong Acid or Base?

Strong acids and bases are characterized by the way their constituent molecules are both fully ionized in a solution. Only a small number of acids and bases break down into nothing but their constituent ions when dissolved in water. Most of the seven strong acids, and eight strong bases, have some use in industrial applications.

Hydrochloric acid is one of the better-known acids in this category. It occurs naturally in the stomach, where the strong acidic environment facilitates the digestion of protein. Sulfuric acid, perchloric acid and nitric acid are also considered strong acids. The bases, such as lithium hydroxide, cesium hydroxide and potassium hydroxide, among others, are powerful agents that can be used to neutralize acids and dissolve organic matter. They can even dissolve certain metals, such as aluminum.

While strong bases always dissociate in solution, strong acids are less consistent. Sulfuric acid, for example, is only strong during the first phase of its dissociation. The thoroughness of an acid's ionization also declines as its concentration increases. In general, an acid is considered strong if it completely dissociates in a solution of 1.0 M or less. For bases, the threshold for dissociation is at concentrations of 0.01 M or less.