Hydronium


Also found in: Dictionary, Medical, Acronyms, Wikipedia.

Hydronium

 

a hydrated hydrogen ion in aqueous solution, H3O+. In solution the free hydrogen ion (that is, the nucleus of the hydrogen atom—the proton) is bound to the water molecules in the solution, forming mainly the hydronium ion: H+ + H2O = H3O+. Because of the small size of the proton (10−13 cm; other atoms have radii on the order of 10−8 cm) a strong electrical field is created, and there is covalent bonding between the proton and the unshared pair of electrons of the oxygen atom in water. The formation of the hydronium ion is analogous to the formation of the ammonium ion, NH4+; it has been established that the crystal hydrate of perchloric acid, HClO4H2O, has an ionic crystal lattice that is isomorphic with ammonium perchlorate, NH4+C104. In crystals the H3O+ ion is called oxonium (as distinct from the hydronium ion, H3O+, which is in solution). Because of the association of water molecules, the hydronium ion binds a larger amount of water. The resultant hydrated hydronium ions have the formulas H5O2+, H7O3+, and H9O4+.

REFERENCES

Samoilov, O. Ia. Struktura vodnykh rastvorov elektrolitov i gidratat-siia ionov. Moscow, 1957.
Neniţescu, C. Obshchaia khimiia. Moscow, 1968. (Translated from Rumanian.)
References in periodicals archive ?
The hydroxide ion also forms more-complicated intermediate structures in water than the hydronium ion does.
The pH determination tells the presence of the dissociated hydronium ion.
1) Environmental factors: The main causes affecting the engineering of concrete containing S0 ~ 4-, Mg and ~, CI, Ca 2+ hydronium concentration, reaction zones, and the dissolution of the freezing cycle and alternately dry and wet conditions and had eight aspects.
The hydronium ions can penetrate the cellulose chains in these amorphous domains promoting the hydrolytic cleavage of the glycosidic bonds and finally releasing individual crystallites.
In the hydrated phase, water moieties bridge the HPA molecules by forming hydronium ions such as [H.
The standard free energy of reaction is 41+24 k J/mol and the standard free energy of formation is -3192 [+ or -] 25 kJ/mol for potassium hydronium jarosite (Brown 1970).