Strong acid

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A strong acid is an acid that dissociates completely in an aqueous solution, or in other terms, with a pK_a < -1.74, that of hydronium. This generally means that in aqueous solution at standard temperature and pressure, the concentration of hydronium ions is equal to the concentration of strong acid introduced to the solution. While strong acids are generally assumed to be the most corrosive, this is not always true. The carborane superacid (H(CHB₁₁Cl₁₁</sub>), which is one million times stronger than sulfuric acid, is entirely non-corrosive. The equation for complete dissociation of an acid in aqueous solution is as follows:

HA(aq) → H⁺(aq) + A^-(aq)

In any other acid-water reaction, dissociation is not complete, so will be represented as an equilibrium, not a completed reaction. The typical definition of a weak acid is any acid that does not dissociate completely. The difference separating the acid dissociation constants of strong acids from all other acids is so great that this is a reasonable demarkation.

Due to the complete dissociation of strong acids in aqueous solution, the concentration of hydronium ions in the water is equal to the concentration of the acid introduced to solution: [HA] = [H⁺] = [A^-]; pH = -log[H+].

The inorganic strong acids (in order from strongest to weakest):