Hydrogen ion
This article needs additional citations for verification. (October 2014) |
A hydrogen ion is created when a hydrogen atom loses an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space.[1] Due to its extremely high charge density of approximately 2×1010 times that of a sodium ion, the bare hydrogen ion cannot exist freely in solution as it readily hydrates, i.e., bonds quickly.[2] The hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes.[3] Depending on the charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions.
Cation (positively charged)
A hydrogen atom is made up of a nucleus with charge +1, and a single electron. Therefore, the only positively charged ion possible has charge +1. It is noted H+.
Depending on the isotope in question, the hydrogen cation has different names:
- Hydron: general name referring to the positive ion of any hydrogen isotope (H+)
- Proton: 1H+ (i.e. the cation of protium)
- Deuteron: 2H+, D+
- Triton: 3H+, T+
In addition, the ions produced by the reaction of these cations with water as well as their
- Hydronium ion: H3O+
- Zundel cation: H5O2+ (named for Georg Zundel)
- Eigen cation: H9O4+ (or H3O+ •3H2O) (named for Manfred Eigen)
Zundel cations and Eigen cations play an important role in proton diffusion according to the Grotthuss mechanism.
In connection with acids, "hydrogen ions" typically refers to hydrons.
In the image at left the hydrogen atom (center) contains a single proton and a single electron. Removal of the electron gives a cation (left), whereas addition of an electron gives an anion (right). The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only cation that has no electrons, but even cations that (unlike hydrogen) still retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived.
Anion (negatively charged)
Hydrogen
- Hydride: general name referring to the negative ion of any hydrogen isotope (H−)
- Protide: 1H−
- Deuteride: 2H−, D −
- Tritide: 3H−, T −
Uses
Hydrogen ions drive
Hydrogen ions concentration, measured as pH, is also responsible for the
Ocean acidification
The concentration of hydrogen ions and pH are inversely proportional; in an aqueous solution, an increased concentration of hydrogen ions yields a low pH, and subsequently, an acidic product. By definition, an acid is an ion or molecule that can donate a proton, and when introduced to a solution it will react with water molecules (H2O) to form a hydronium ion (H3O+), a conjugate acid of water.[4] For simplistic reasoning, the hydrogen ion (H+) is often used to abbreviate the hydronium ion.
In the surface waters, dissolved atmospheric carbon dioxide (CO2(aq)) reacts with water molecules to form carbonic acid (H2CO3), a weak diprotic acid. Diprotic acids consist of two ionizable hydrogen atoms in each molecule.[12] In an aqueous solution, partial dissociation of carbonic acid releases a hydrogen proton (H+) and a bicarbonate ion (HCO3−), and subsequently, the bicarbonate ion dissociates into an additional hydrogen proton and a carbonate ion (CO32-).[13] The dissolving and dissociating of these inorganic carbon species generate an increase in the concentration of hydrogen ions and inversely lowers ambient surface ocean pH. The carbonate buffering system governs the acidity of seawater by maintaining dissolved inorganic carbon species in chemical equilibrium.
The chemical equation consists of reactants and products that may react in either direction. More reactants added to a system yield more product production (the chemical reaction shifts to the right) and if more product is added, additional reactants will form, shifting the chemical reaction to the left. Therefore, in this model, a high concentration of the beginning reactant, carbon dioxide, produces an increased amount of end-product (H+ and CO32-), thus lowering pH and creating a more acidic solution. The natural buffering system of the ocean resist the change in pH by producing more bicarbonate ions generated by free acid protons reacting with carbonate ions to form an alkaline character.
See also
References
- ^ "Hydrogen ion - chemistry". britannica.com. Retrieved 18 March 2018.
- ^ due to its extremely high charge density of approximately 2×1010 times that of a sodium ion
- ^ OpenStax, Chemistry. OpenStax CNX. Jun 20, 2016 http://cnx.org/contents/[email protected].
- ^ W.S. Broecker, T. Takahashi (1997) Neutralization of fossil fuel CO2 by marine calcium carbonate
- ^ P.N. Pearson, M.R. Palmer (2000) Atmospheric carbon dioxide concentrations over the past 60 million years Nature, 406, pp. 695-699
- ^ C.L. Sabine, et al. (2004). The oceanic sink for anthropogenic CO2 Science, 305 (5682), pp. 367-371
- ^ Lal R. (2008). Carbon sequestration. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 363(1492), 815–830. https://doi.org/10.1098/rstb.2007.2185
- ^ Ben I. Mcneil & Richard J. Matear (2007). Climate change feedbacks on future oceanic acidification, Tellus B: Chemical and Physical Meteorology, 59:2, 191-198
- ^ Hessen, D., Ågren, G., Anderson, T., Elser, J., & De Ruiter, P. (2004). Carbon Sequestration in Ecosystems: The Role of Stoichiometry. Ecology, 85(5), 1179-1192. Retrieved November 22, 2020, from http://www.jstor.org/stable/3450161
- ^ Avishay DM, Tenny KM. Henry's Law. [Updated 2020 Sep 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK544301/
- ^ OpenStax, Chemistry. OpenStax CNX. Jun 20, 2016 http://cnx.org/contents/[email protected].
- ^ OpenStax, Chemistry. OpenStax CNX. Jun 20, 2016 http://cnx.org/contents/[email protected].
- ^ Middelburg, J. J., Soetaert, K., & Hagens, M. (2020). Ocean Alkalinity, Buffering and Biogeochemical Processes. Reviews of geophysics (Washington, D.C. : 1985), 58(3), e2019RG000681. https://doi.org/10.1029/2019RG000681
- ^ Matsumoto, K. (2007). Biology-mediated temperature control on atmosphericpCO2and ocean biogeochemistry. Geophysical Research Letters, 34(20). doi:10.1029/2007gl031301