Strong acid

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Acids and bases:
Acid-base reaction theories
pH
Self-ionization of water
Buffer solutions
Systematic naming
Electrochemistry
Acids:
Strong acids
Weak acids
Bases:
Strong bases
Weak bases

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), 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+].

Contents

1 Some Common Strong Acids (As Ionisers)

1.1 Extremely Strong Acids (As Ionisers)

2 External links
3 References

Some Common Strong Acids (As Ionisers)

(Strongest to weakest)

Perchloric acid HClO₄
Hydroiodic acid HI
Hydrobromic acid HBr
Hydrochloric acid HCl
Sulfuric acid H₂SO₄ (K_a1/first dissociation only)
Nitric acid HNO₃
Hydronium ion H₃O⁺

Some chemists include chloric acid (HClO₃), bromic acid (HBrO₃), perbromic acid (HBrO₄), iodic acid (HIO₃), and periodic acid (HIO₄) as strong acids, although these are not universally accepted.

Extremely Strong Acids (As Ionisers)

(Strongest to weakest)

Fluoroantimonic acid HFSbF₅
Magic acid FSO₃HSbF₅
Fluorosulfuric acid FSO₃H

External links

http://www.cm.utexas.edu/academic/courses/Spring2002/CH301/McDevitt/strong.htm
http://jchemed.chem.wisc.edu/Journal/Issues/2000/Jul/abs849.html
Titration of acids [- freeware for data analysis and simulation of potentiometric titration curves]

References

Hill, John W., et al. "General Chemistry." 4th ed. New Jersey: Prentice Hall, 2005.

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