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Other examples of inorganic polyprotic acids include anions of sulfuric acid, phosphoric acid and hydrogen sulfide that have lost one or more protons. In organic chemistry and biochemistry, important examples include amino acids and derivatives of citric acid. Although an amphiprotic species must be amphoteric, the converse is not true.
Acid strength is the tendency of an acid, symbolised by the chemical formula HA, to dissociate into a proton, H +, and an anion, A −.The dissociation or ionization of a strong acid in solution is effectively complete, except in its most concentrated solutions.
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO 2 OH, are relatively stronger acids. Alcohols, with –OH, can act as acids but they are usually very weak.
Most often, hydrogen evolution is induced by acids. The alkali and alkaline earth metals, aluminium, zinc, manganese, and iron react readily with aqueous acids. This reaction is the basis of the Kipp's apparatus, which once was used as a laboratory gas source: Zn + 2 H + → Zn 2+ + H 2. In the absence of acid, the evolution of H 2 is slower.
Carbonic acid is an illustrative example of the Lewis acidity of an acidic oxide. CO 2 + 2OH − ⇌ HCO 3 − + OH − ⇌ CO 3 2− + H 2 O. This property is a key reason for keeping alkali chemicals well sealed from the atmosphere, as long-term exposure to carbon dioxide in the air can degrade the material.
The self-ionization of water (also autoionization of water, autoprotolysis of water, autodissociation of water, or simply dissociation of water) is an ionization reaction in pure water or in an aqueous solution, in which a water molecule, H 2 O, deprotonates (loses the nucleus of one of its hydrogen atoms) to become a hydroxide ion, OH −.
Nitric acid, with a pK value of around −1.7, behaves as a strong acid in aqueous solutions with a pH greater than 1. [23] At lower pH values it behaves as a weak acid. pK a values for strong acids have been estimated by theoretical means. [24] For example, the pK a value of aqueous HCl has been estimated as −9.3.
Strong bases hydrolyze in water almost completely, resulting in the leveling effect." [7] In this process, the water molecule combines with a strong base, due to the water's amphoteric ability; and, a hydroxide ion is released. [7] Very strong bases can even deprotonate very weakly acidic C–H groups in the absence of water.