Hydronium ion . The hydronium ion is a cation that is formed in water when it is in the presence of H ^ + ( hydrogen ) cations . These cations are not found freely, as they are very reactive and dissolve very easily with the water molecules that circulate around it.
Summary
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- 1 Training
- 2 Solvation
- 3 Salts
- 4 Location
- 5 Interstellar hydronium
- 6 Sources
Training
Hydronium is the cation that forms in water in the presence of H + hydrogen cations. These cations are not presented freely; they are extremely reactive and are immediately solvated by the surrounding water molecules .
Hydronium ions are found in pure water at a concentration of 10 ^ -7M. Without the presence of acidic or basic species, ions are formed through the reaction of two water molecules, following the reaction: 2 H2O → H3O ^ + + OH ^ – This reaction has a constant, Kw = 10 ^ -14.
The hydronium ion is quite acidic, since at a temperature of 25ºC it has a pKa = -1.7. Hydronium is the most acidic species that can be found in water, taking a certain amount of solvent so that the reaction can occur. The acidity of this species is taken as a model for other species, for example a weak acid is better, or must be a better hydronium donor than is pure water.
In a solution, pH is the measure taken from the concentration of the protons. The protons will react with water to give rise to hydronium, and can be considered as the concentration of these.
Solvation
Solvation is not yet fully defined for water molecules that solvate hydrogen cations (protons), as there are numerous different forms of solvation. After a study carried out at freezing temperature on the solvation of water, it was deduced that the average hydration that takes place in cold water is on average, H3O ^ + (H2O) 6, that is, six water molecules that solvate a proton and in turn you show inability to solvate another spice, as long as it is simultaneously.
There are considerably large solvation structures. Protons have high reactivities, which is not a problem for them to be associated with other different species. Two of the most studied and known structures with the so-called cationic species, Zundel and Eigen.
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In the case of strong acids, in many of them there is the possibility of crystallizing their hydronium salts, which are quite stable. These salts are sometimes known as acidic monohydrates. In general, an acid with an ionization constant of 10 ^ 9 or greater is capable of forming such salts, while, on the other hand, acids with a smaller constant will be unable to do so.
Location
Hydronium is abundant in space and is found in dense and diffuse molecular clouds, as well as in the plasma of comet tails. Detected sources of Hydronium include the regions of Sagittarius B2, Orion OMC-1 , Orion BN-IRc2 , Orion KL and Comet Hale-Bopp .
Interstellar hydronium
Interstellar hydronium is formed by a chain of reactions that begin with the ionization of H2 into H2 + under cosmic radiation . H3O + can produce both OH and H2O through recombinant dissociative reactions, which occur very quickly even at the extremely low temperatures of dense molecular clouds. This reveals that Hydronium plays a very important role in interstellar ionic chemistry.