Aqueous cation H₃O⁺, the type of oxonium ion produced by protonation of water
Hydronium
3D diagram showing the pyramidal structure of the hydroxonium ion
Ball-and-stick model of the hydronium ion
3D electric potential surface of the hydroxonium cation
Van der Waals radius of Hydronium
Names
IUPAC name
oxonium
Other names
hydronium ion
Identifiers
CAS Number
13968-08-6Y
3D model (JSmol)
Interactive image
ChEBI
CHEBI:29412Y
ChemSpider
109935Y
Gmelin Reference
141
PubChem CID
123332
CompTox Dashboard (EPA)
DTXSID20893597
InChI
InChI=1S/H2O/h1H2/p+1
Key: XLYOFNOQVPJJNP-UHFFFAOYSA-O
SMILES
[OH3+]
Properties
Chemical formula
H3O+
Molar mass
19.023 g·mol−1
Acidity (pKa)
0
Conjugate base
Water
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Chemical compound
In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the cation [H3O]+, also written as H3O+, the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H+) to the surrounding water molecules (H2O). In fact, acids must be surrounded by more than a single water molecule in order to ionize, yielding aqueous H+ and conjugate base. Three main structures for the aqueous proton have garnered experimental support: the Eigen cation, which is a tetrahydrate, H3O+(H2O)3, the Zundel cation, which is a symmetric dihydrate, H+(H2O)2, and the Stoyanov cation, an expanded Zundel cation, which is a hexahydrate: H+(H2O)2(H2O)4.[1][2] Spectroscopic evidence from well-defined IR spectra overwhelmingly supports the Stoyanov cation as the predominant form.[3][4][5][6][non-primary source needed] For this reason, it has been suggested that wherever possible, the symbol H+(aq) should be used instead of the hydronium ion.[2]
^Reed, C.A. (2013). "Myths about the proton. The nature of H+ in condensed media". Acc. Chem. Res. 46 (11): 2567–2575. doi:10.1021/ar400064q. PMC 3833890. PMID 23875729.
^ abSilverstein, Todd P. (2014). "The aqueous proton is hydrated by more than one water molecule: Is the hydronium ion a useful conceit?". J. Chem. Educ. 91 (4): 608–610. Bibcode:2014JChEd..91..608S. doi:10.1021/ed400559t.
^Thamer, M.; DeMarco, L.; Ramesha, K.; Mandel, A.; Tokmakoff, A. (2015). "Ultrafast 2D IR spectroscopy of the excess proton in liquid water". Science. 350 (6256): 78–82. Bibcode:2015Sci...350...78T. doi:10.1126/science.aab3908. PMID 26430117. S2CID 27074374.
^Daly Jr., C.A.; Streacker, L.M.; Sun, Y.; Pattenaude, S.R.; Hassanali, A.A.; Petersen, P.B.; et al. (2017). "Decomposition of the experimental Raman and IR spectra of acidic water into proton, special pair, and counterion contributions". J. Phys. Chem. Lett. 8 (21): 5246–5252. doi:10.1021/acs.jpclett.7b02435. PMID 28976760.
^Dahms, F.; Fingerhut, B.P.; Nibbering, E.T.; Pines, E.; Elsaesser, T. (2017). "Large-amplitude transfer motion of hydrated excess protons mapped by ultrafast 2D IR spectroscopy". Science. 357 (6350): 491–495. Bibcode:2017Sci...357..491D. doi:10.1126/science.aan5144. PMID 28705988. S2CID 40492001.
^Fournier, J.A.; Carpenter, W.B.; Lewis, N.H.; Tokmakoff, A. (2018). "Broadband 2D IR spectroscopy reveals dominant asymmetric H5O2+ proton hydration structures in acid solutions". Nature Chemistry. 10 (9): 932–937. Bibcode:2018NatCh..10..932F. doi:10.1038/s41557-018-0091-y. OSTI 1480907. PMID 30061612. S2CID 51882732.
In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the cation [H3O]+, also written as H3O+, the type of oxonium...
ions (hydronium ions). A combined IR, Raman, X-ray, and neutron diffraction study of concentrated hydrochloric acid showed that the hydronium ion forms...
acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized...
it being a solid and stable hydronium salt. It consists of hydronium cations [H3O]+ and perchlorate anions ClO−4. Hydronium perchlorate is produced by...
appears in the Born equation for calculating the hydration enthalpy of hydronium. Although protons have affinity for oppositely charged electrons, this...
half-life of a bottom quark ~1 picosecond – lifetime of a single H 3O+ (hydronium) ion in water at 20 °C picoseconds to nanoseconds – phenomena observable...
The acid dissociates in the aqueous environment producing hydronium ions, [H3O]+. A hydronium ion protonates the electronegative oxygen atom of the ethanol...
basis of molecular dynamics simulation. The calculated energetics of the hydronium solvation shells were reported in 2007 and it was suggested that the activation...
H3O+ (hydronium ions) per litre of solution (and also 10−10.5 moles per litre OH−). A pH of 7, defined as neutral, has 10−7 moles of hydronium ions per...
anion linked via hydrogen bonds to H2O and H3O+ centers. An example is hydronium perchlorate. Perchloric acid forms an azeotrope with water, consisting...
dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations. The salt also dissociates into its constituent anions and cations...
a weak acid, hydrogen phthalate reacts reversibly with water to give hydronium (H3O+) and phthalate ions. HP− + H2O ⇌ P2− + H3O+ KHP can be used as a...
weak solution of hydronium hydroxide—there is an equilibrium 2H 2O ⇌ H 3O+ + OH− , in combination with solvation of the resulting hydronium and hydroxide...
the hydronium ion concentration in a solution, as expressed on a negative logarithmic scale. Thus, solutions that have a low pH have a high hydronium ion...
leads to the formation of a H2O+ ion, which rapidly reacts to become hydronium (H3O+) and a short lived hydroxyl radical (•OH)) 200 fs – the average...
which the hydroxide ions from the Mg(OH)2 combine with acidic H+ ions (or hydronium ions) produced in the form of hydrochloric acid by parietal cells in the...
0×10−14. Note that in solution H+ exists as the hydronium ion H3O+, and further aquation of the hydronium ion has negligible effect on the dissociation...
form a hydronium ion (H3O+), a conjugate acid of water. For simplistic reasoning, the hydrogen ion (H+) is often used to abbreviate the hydronium ion. Ocean...
intersolvent scale which involves the transfer activity coefficient of hydronium/lyonium ion. pH is an example of an acidity function, but there are others...
bonds and 1+ formal charge. The simplest oxonium ion is the hydronium ion (H3O+). Hydronium is one of a series of oxonium ions with the formula RnH3−nO+...
general reaction with hydronium is in equilibrium due to the similarity in pKa between trifluoroacetic acid and the hydronium ion. One convenient method...
lead-acid electrochemical cell, electric currents are composed of positive hydronium ions flowing in one direction, and negative sulfate ions flowing in the...
of corrosion and involves replacement of alkali ions in the glass by a hydronium (H3O+) ion from the solution. It causes an ion-selective depletion of...
constant. The liberated proton combines with a water molecule to give a hydronium (or oxonium) ion H3O+ (naked protons do not exist in solution), and so...
counter. Upon reaching the stomach, the powdered antacid salts bind to hydronium (H+) ions, producing chloride salts, carbon dioxide, and water. This process...
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