Jump to content

Electrolyte

From Wikipedia, the free encyclopedia

For the R.E.M. song, seeElectrolite.

Anelectrolyteis a substance that conductselectricitythrough the movement ofions,but not through the movement ofelectrons.[1][2][3]This includes most solublesalts,acids,andbases,dissolved in apolar solventlike water. Upon dissolving, the substance separates intocationsandanions,which disperse uniformly throughout the solvent.[4]Solid-state electrolytesalso exist. In medicine and sometimes in chemistry, the term electrolyte refers to the substance that is dissolved.[5][6]

Electrically, such a solution is neutral. If anelectric potentialis applied to such a solution, the cations of the solution are drawn to theelectrodethat has an abundance ofelectrons,while the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. Some gases, such ashydrogen chloride(HCl), under conditions of high temperature or low pressure can also function as electrolytes.[clarification needed]Electrolyte solutions can also result from the dissolution of some biological (e.g.,DNA,polypeptides) orsynthetic polymers(e.g.,polystyrene sulfonate), termed "polyelectrolytes",which contain chargedfunctional groups.A substance that dissociates into ions in solution or in the melt acquires the capacity to conduct electricity.Sodium,potassium,chloride,calcium,magnesium,andphosphatein a liquid phase are examples of electrolytes.

In medicine,electrolyte replacementis needed when a person has prolongedvomitingordiarrhea,and as a response to sweating due to strenuous athletic activity. Commercial electrolyte solutions are available, particularly for sick children (such asoral rehydrationsolution,Suero Oral,orPedialyte) and athletes (sports drinks). Electrolyte monitoring is important in the treatment ofanorexiaandbulimia.

In science, electrolytes are one of the main components ofelectrochemical cells.[2]

In clinicalmedicine,mentions of electrolytes usually refermetonymicallyto the ions, and (especially) to theirconcentrations(in blood, serum, urine, or other fluids). Thus, mentions of electrolyte levels usually refer to the various ion concentrations, not to the fluid volumes.

Etymology

[edit]

The wordelectrolytederives fromAncient Greekήλεκτρο- (ēlectro-), prefix originally meaningamberbut in modern contexts related to electricity, and λυτός (lytos), meaning "able to be untied or loosened".[citation needed]

History

[edit]
Svante Arrhenius,father of the concept of electrolyte dissociation inaqueous solutionfor which he received theNobel Prize in Chemistryin 1903

In his 1884 dissertation,Svante Arrheniusput forth his explanation of solid crystalline salts disassociating into paired charged particles when dissolved, for which he won the 1903Nobel Prizein Chemistry.[7][8][9][10]Arrhenius's explanation was that in forming a solution, the salt dissociates into charged particles, to whichMichael Faraday(1791-1867) had given the name "ions"many years earlier. Faraday's belief had been that ions were produced in the process ofelectrolysis.Arrhenius proposed that, even in the absence of an electric current, solutions of salts contained ions. He thus proposed that chemical reactions in solution were reactions between ions.[8][9][10]

Shortly after Arrhenius's hypothesis of ions,Franz Hofmeisterand Siegmund Lewith[11][12][13]found that different ion types displayed different effects on such things as the solubility of proteins. A consistent ordering of these different ions on the magnitude of their effect arises consistently in many other systems as well. This has since become known as theHofmeister series.

While the origins of these effects are not abundantly clear and have been debated throughout the past century, it has been suggested that the charge density of these ions is important[14]and might actually have explanations originating from the work ofCharles-Augustin de Coulombover 200 years ago.

Formation

[edit]

Electrolyte solutions are normally formed when salt is placed into asolventsuch as water and the individual components dissociate due to thethermodynamicinteractions between solvent and solute molecules, in a process called "solvation".For example, when table salt (sodium chloride), NaCl, is placed in water, the salt (a solid) dissolves into its component ions, according to the dissociation reaction:[citation needed]

NaCl(s)→ Na+(aq)+ Cl−(aq)

It is also possible for substances to react with water, producing ions. For example,carbon dioxidegas dissolves in water to produce a solution that containshydronium,carbonate,andhydrogen carbonateions.[citation needed]

Molten saltscan also be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. In particular, ionic liquids, which are molten salts with melting points below 100 °C,[15]are a type of highly conductive non-aqueous electrolytes and thus have found more and more applications in fuel cells and batteries.[16]

An electrolyte in a solution may be described as "concentrated" if it has a high concentration of ions, or "dilute" if it has a low concentration. If a high proportion of the solute dissociates to form free ions, the electrolyte is strong; if most of the solute does not dissociate, the electrolyte is weak. The properties of electrolytes may be exploited using electrolysis to extract constituent elements and compounds contained within the solution.[citation needed]

Alkaline earth metals form hydroxides that are strong electrolytes with limited solubility in water, due to the strong attraction between their constituent ions. This limits their application to situations where high solubility is required.[17]

In 2021, researchers have found that electrolyte can "substantially facilitate electrochemical corrosion studies in less conductive media".[18]

Physiological importance

[edit]
See also:Electrochemical gradient,Acid–base homeostasis,andElectrolyte imbalance

Inphysiology,the primary ions of electrolytes aresodium(Na+),potassium(K+),calcium(Ca2+),magnesium(Mg2+),chloride(Cl−),hydrogen phosphate(HPO42−), andhydrogen carbonate(HCO3−).[19][failed verification]The electric charge symbols of plus (+) and minus (−) indicate that the substance is ionic in nature and has an imbalanced distribution of electrons, the result ofchemical dissociation.Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte;[20]both are involved in fluid balance andblood pressurecontrol.[21]

All known multicellular lifeforms require a subtle and complex electrolyte balance between theintracellularandextracellularenvironments.[19]In particular, the maintenance of preciseosmoticgradientsof electrolytes is important. Such gradients affect and regulate thehydrationof the body as well asblood pH,and are critical fornerveandmusclefunction. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control.[22]

Both muscle tissue andneuronsare considered electric tissues of the body. Muscles and neurons are activated by electrolyte activity between theextracellular fluidorinterstitial fluid,andintracellular fluid.Electrolytes may enter or leave the cell membrane through specialized protein structures embedded in theplasma membranecalled "ion channels".For example,muscle contractionis dependent upon the presence of calcium (Ca2+), sodium (Na+), and potassium (K+). Without sufficient levels of these key electrolytes, muscle weakness or severe muscle contractions may occur.[citation needed][23]

Electrolyte balance is maintained by oral, or in emergencies, intravenous (IV) intake of electrolyte-containing substances, and is regulated byhormones,in general with thekidneysflushing out excess levels. In humans, electrolytehomeostasisis regulated by hormones such asantidiuretic hormones,aldosteroneandparathyroid hormones.Seriouselectrolyte disturbances,such asdehydrationandoverhydration,may lead to cardiac and neurological complications and, unless they are rapidly resolved, will result in amedical emergency.

Measurement

[edit]

Measurement of electrolytes is a commonly performed diagnostic procedure, performed viablood testingwithion-selective electrodesorurinalysisbymedical technologists.The interpretation of these values is somewhat meaningless without analysis of theclinical historyand is often impossible without parallel measurements ofrenal function.The electrolytes measured most often are sodium and potassium. Chloride levels are rarely measured except forarterial blood gasinterpretations since they are inherently linked to sodium levels. One important test conducted on urine is thespecific gravitytest to determine the occurrence of anelectrolyte imbalance.[citation needed]

Rehydration

[edit]

According to a study paid for by theGatorade Sports Science Institute,electrolyte drinks containing sodium and potassium salts replenish the body's water and electrolyte concentrations after dehydration caused byexercise,excessive alcohol consumption,diaphoresis(heavy sweating), diarrhea, vomiting,intoxicationor starvation; the study says that athletes exercising in extreme conditions (for three or more hours continuously, e.g. amarathonortriathlon) who do not consume electrolytes riskdehydration(orhyponatremia).[24][needs independent confirmation]

A home-made electrolyte drink can be made by using water, sugar and saltin precise proportions.[25]It is important to includeglucose(sugar) to utilise the co-transport mechanism of sodium and glucose. Commercial preparations are also available[26]for both human and veterinary use.

Electrolytes are commonly found infruit juices,sports drinks, milk, nuts, and many fruits and vegetables (whole or in juice form) (e.g., potatoes,avocados).

Electrochemistry

[edit]
Main article:Electrolysis

Whenelectrodesare placed in an electrolyte and avoltageis applied, the electrolyte will conduct electricity. Loneelectronsnormally cannot pass through the electrolyte; instead, a chemical reaction occurs at thecathode,providing electrons to the electrolyte. Another reaction occurs at theanode,consuming electrons from the electrolyte. As a result, a negative charge cloud develops in the electrolyte around the cathode, and a positive charge develops around the anode. The ions in the electrolyte neutralize these charges, enabling the electrons to keep flowing and the reactions to continue.[citation needed]

Electrolytic cellproducingchlorine(Cl2) andsodium hydroxide(NaOH) from a solution of common salt

For example, in a solution of ordinary table salt (sodium chloride, NaCl) in water, the cathode reaction will be

2 H2O + 2e−→ 2 OH−+ H2

andhydrogengas will bubble up; the anode reaction is

2 NaCl → 2 Na++ Cl2+ 2e−

andchlorinegas will be liberated into solution where it reacts with the sodium and hydroxyl ions to producesodium hypochlorite- householdbleach.The positively charged sodium ions Na+will react toward the cathode, neutralizing the negative charge of OH−there, and the negatively charged hydroxide ions OH−will react toward the anode, neutralizing the positive charge of Na+there. Without the ions from the electrolyte, the charges around the electrode would slow down continued electron flow;diffusionof H+and OH−through water to the other electrode takes longer than movement of the much more prevalent salt ions. Electrolytes dissociate in water because water molecules are dipoles and the dipoles orient in an energetically favorable manner tosolvatethe ions.

In other systems, the electrode reactions can involve the metals of the electrodes as well as the ions of the electrolyte.

Electrolytic conductors are used in electronic devices where the chemical reaction at a metal-electrolyte interface yields useful effects.

  • Inbatteries,two materials with different electron affinities are used as electrodes; electrons flow from one electrode to the other outside of the battery, while inside the battery the circuit is closed by the electrolyte's ions. Here, the electrode reactions convert chemical energy to electrical energy.[27]
  • In somefuel cells,a solid electrolyte orproton conductorconnects the plates electrically while keeping the hydrogen and oxygen fuel gases separated.[28]
  • Inelectroplatingtanks, the electrolyte simultaneously deposits metal onto the object to be plated, and electrically connects that object in the circuit.
  • In operation-hours gauges, two thin columns ofmercuryare separated by a small electrolyte-filled gap, and, as charge is passed through the device, the metal dissolves on one side and plates out on the other, causing the visible gap to slowly move along.
  • Inelectrolytic capacitorsthe chemical effect is used to produce an extremely thindielectricorinsulatingcoating, while the electrolyte layer behaves as one capacitor plate.
  • In somehygrometersthe humidity of air is sensed by measuring the conductivity of a nearly dry electrolyte.
  • Hot, softened glass is an electrolytic conductor, and some glass manufacturers keep the glass molten by passing a large current through it.

Solid electrolytes

[edit]
Main articles:Fast-ion conductorandSolid-state electrolyte

Solid electrolytes can be mostly divided into four groups described below.

Gel electrolytes

[edit]

Gel electrolytes – closely resemble liquid electrolytes. In essence, they are liquids in a flexiblelattice framework.Variousadditivesare often applied to increase theconductivityof such systems.[27][29]

Ceramic electrolytes

[edit]

Solid ceramic electrolytes –ionsmigrate through the ceramic phase by means of vacancies orinterstitialswithin thelattice.There are alsoglassy-ceramicelectrolytes.

Polymer electrolytes

[edit]
Main article:Polymer electrolytes

Dry polymer electrolytes – differ from liquid and gel electrolytes in the sense that salt is dissolved directly into the solid medium. Usually it is a relatively high-dielectric constantpolymer(PEO,PMMA,PAN,polyphosphazenes,siloxanes,etc.) and a salt with lowlattice energy.In order to increase themechanical strengthand conductivity of such electrolytes, very oftencompositesare made, and inert ceramic phase is introduced. There are two major classes of such electrolytes: polymer-in-ceramic, and ceramic-in-polymer.[30][31][32]

Organic plastic electrolytes

[edit]

Organic ionic plastic crystals – are a typeorganic saltsexhibitingmesophases(i.e. astate of matterintermediate between liquid and solid), in which mobile ions are orientationally or rotationally disordered while their centers are located at the ordered sites in the crystal structure.[28]They have various forms of disorder due to one or more solid–solidphase transitionsbelow themelting pointand have thereforeplasticproperties and good mechanical flexibility as well as an improved electrode-electrolyte interfacial contact. In particular, protic organic ionic plastic crystals (POIPCs),[28]which are solidproticorganic salts formed byprotontransfer from aBrønsted acidto a Brønsted base and in essence are proticionic liquidsin themolten state,have found to be promising solid-stateproton conductorsforfuel cells.Examples include1,2,4-triazoliumperfluorobutanesulfonate[28]andimidazoliummethanesulfonate.[33]

See also

[edit]

References

[edit]
  1. ^Enderby JE, Neilson GW (1 June 1981)."The structure of electrolyte solutions".Reports on Progress in Physics.44(6): 593–653.doi:10.1088/0034-4885/44/6/001.ISSN0034-4885.S2CID250852242.Archivedfrom the original on 18 December 2021.Retrieved18 December2021.
  2. ^abPetrovic S (29 October 2020).Battery technology crash course: a concise introduction.Springer.ISBN978-3-030-57269-3.OCLC1202758685.
  3. ^Winie T, Arof AK, Thomas S (18 February 2020).Polymer Electrolytes: Characterization Techniques and Energy Applications.John Wiley & Sons.ISBN978-3-527-34200-6.
  4. ^M Andreev, JJ de Pablo, A Chremos, J F Douglas (2018). "Influence of ion solvation on the properties of electrolyte solutions".The Journal of Physical Chemistry B.122(14): 4029–4034.doi:10.1021/acs.jpcb.8b00518.PMID29611710.
  5. ^Wilkins LW (2007).Fluids and Electrolytes.Lippincott Williams & Wilkins.ISBN978-1-58255-923-0.
  6. ^"electrolyte".National Cancer Institute.2 February 2011.Archivedfrom the original on 23 April 2018.Retrieved18 December2021.
  7. ^"The Nobel Prize in Chemistry 1903".Archivedfrom the original on 8 July 2018.Retrieved5 January2017.
  8. ^abHarris W, Levey J, eds. (1975).The New Columbia Encyclopedia(4th ed.). New York City: Columbia University. p.155.ISBN978-0-231035-729.
  9. ^abMcHenry C, ed. (1992).The New Encyclopædia Britannica.Vol. 1 (15 ed.). Chicago: Encyclopædia Britannica, Inc. p. 587.Bibcode:1991neb..book.....G.ISBN978-085-229553-3.
  10. ^abCillispie C, ed. (1970).Dictionary of Scientific Biography(1 ed.). New York City: Charles Scribner's Sons. pp. 296–302.ISBN978-0-684101-125.
  11. ^Franz Hofmeister (1888). "Zur Lehre Von Der Wirkung Der Salze".Naunyn-Schmiedeberg's Arch. Pharmacol.
  12. ^W. Kunz, J. Henle, B. W. Ninham (2004)."'Zur Lehre von der Wirkung der Salze' (about the science of the effect of salts): Franz Hofmeister's historical papers ".Current Opinion in Colloid & Interface Science.9(1–2): 19–37.doi:10.1016/j.cocis.2004.05.005.Archivedfrom the original on 20 January 2022.Retrieved8 November2021.
  13. ^Gregory KP, Elliott GR, Robertson H, Kumar A, Wanless EJ, Webber GB, Craig VS, Andersson GG, Page AJ (2022)."Understanding specific ion effects and the Hofmeister series".Physical Chemistry Chemical Physics.24(21): 12682–12718.Bibcode:2022PCCP...2412682G.doi:10.1039/D2CP00847E.PMID35543205.
  14. ^Kasimir P. Gregory, Erica J. Wanless, Grant B. Webber, Vince S. J. Craig, Alister J. Page (2021)."The Electrostatic Origins of Specific Ion Effects: Quantifying the Hofmeister Series for Anions".Chem. Sci.12(45): 15007–15015.doi:10.1039/D1SC03568A.PMC8612401.PMID34976339.S2CID244578563.
  15. ^Shi J, Sun X, Chunhe Y, Gao Q, Li Y (2002).Ly tử chất lỏng nghiên cứu tiến triển(PDF).Hóa học thông báo(in Simplified Chinese) (4): 243.ISSN0441-3776.Archived fromthe original(PDF)on 2 March 2017.Retrieved1 March2017.
  16. ^ Jiangshui Luo, Jin Hu, Wolfgang Saak, Rüdiger Beckhaus, Gunther Wittstock, Ivo F. J. Vankelecom, Carsten Agert, Olaf Conrad (2011)."Protic ionic liquid and ionic melts prepared from methanesulfonic acid and 1H-1,2,4-triazole as high temperature PEMFC electrolytes".Journal of Materials Chemistry.21(28): 10426–10436.doi:10.1039/C0JM04306K.S2CID94400312.
  17. ^Brown, Chemistry: The Central Science, 14th edition, pg. 680.
  18. ^Matějovský L, Staš M, Dumská K, Pospíšil M, Macák J (1 January 2021)."Electrochemical corrosion tests in an environment of low-conductive ethanol-gasoline blends: Part 1 – Testing of supporting electrolytes".Journal of Electroanalytical Chemistry.880:114879.doi:10.1016/j.jelechem.2020.114879.ISSN1572-6657.S2CID229508133.
  19. ^abAlfarouk KO, Ahmed SB, Ahmed A, Elliott RL, Ibrahim ME, Ali HS, Wales CC, Nourwali I, Aljarbou AN, Bashir AH, Alhoufie ST, Alqahtani SS, Cardone RA, Fais S, Harguindey S, Reshkin SJ (7 April 2020)."The Interplay of Dysregulated pH and Electrolyte Imbalance in Cancer".Cancers.12(4): 898.doi:10.3390/cancers12040898.PMC7226178.PMID32272658.
  20. ^Ye S(, Tang Z( (1986).Màng tế bào Natri bơm và lâm sàng ý nghĩa.Thượng Hải y học[Shanghai Medicine](in Simplified Chinese) (1): 1. Archived fromthe originalon 3 March 2017.Retrieved3 March2017.
  21. ^Tu Z( (2004).Chất điện phân hỗn loạn đối thời kì cuối u trị liệu ảnh hưởng.Trung Hoa Trung Quốc và Phương Tây y tạp chí[Chinese Magazine of Chinese and Western Medicine](in Simplified Chinese) (10). Trương định xương.Ở người bình thường trong cơ thể, Natri ly tử chiếm tế bào ngoại dịch dương ly tử tổng sản lượng 92%, Kali ly tử chiếm tế bào nội dịch dương ly tử tổng sản lượng 98% tả hữu. Natri, Kali ly tử tương đối cân bằng, duy trì toàn bộ tế bào công năng cùng kết cấu hoàn chỉnh. Natri, Kali là nhân thể nội chính yếu chất điện phân thành phần...
  22. ^Open Resources for Nursing, Ernstmeyer K, Christman E (2021),"Chapter 15 Fluids and Electrolytes",Nursing Fundamentals [Internet],Chippewa Valley Technical College,retrieved28 February2024
  23. ^"Reproductive Consequences of Electrolyte Disturbances in Domestic Animals".
  24. ^J, Estevez E, Baquero E, Mora-Rodriguez R (2008). "Anaerobic performance when rehydrating with water or commercially available sports drinks during prolonged exercise in the heat".Applied Physiology, Nutrition, and Metabolism.33(2): 290–298.doi:10.1139/H07-188.PMID18347684.
  25. ^"Rehydration drinks".Webmd. 28 April 2008. Archived fromthe originalon 23 October 2008.Retrieved25 December2018.
  26. ^"Oral Rehydration Salt Suppliers".Rehydrate.org. 7 October 2014.Archivedfrom the original on 7 December 2014.Retrieved4 December2014.
  27. ^abKamil Perzyna, Regina Borkowska, Jaroslaw Syzdek, Aldona Zalewska, Wladyslaw Wieczorek (2011). "The effect of additive of Lewis acid type on lithium–gel electrolyte characteristics".Electrochimica Acta.57:58–65.doi:10.1016/j.electacta.2011.06.014.
  28. ^abcd Jiangshui Luo, Annemette H. Jensen, Neil R. Brooks, Jeroen Sniekers, Martin Knipper, David Aili, Qingfeng Li, Bram Vanroy, Michael Wübbenhorst, Feng Yan, Luc Van Meervelt, Zhigang Shao, Jianhua Fang, Zheng-Hong Luo, Dirk E. De Vos, Koen Binnemans, Jan Fransaer (2015). "1,2,4-Triazolium perfluorobutanesulfonate as an archetypal pure protic organic ionic plastic crystal electrolyte for all-solid-state fuel cells".Energy & Environmental Science.8(4): 1276–1291.doi:10.1039/C4EE02280G.S2CID84176511.
  29. ^"The Roll-to-Roll Battery Revolution".Ev World. Archived fromthe originalon 10 July 2011.Retrieved20 August2010.
  30. ^Syzdek J, Borkowska R, Perzyna K, Tarascon JM, Wieczorek W (2007). "Novel composite polymeric electrolytes with surface-modified inorganic fillers".Journal of Power Sources.173(2): 712–720.Bibcode:2007JPS...173..712S.doi:10.1016/j.jpowsour.2007.05.061.ISSN0378-7753.
  31. ^Syzdek J, Armand M, Marcinek M, Zalewska A, Żukowska G, Wieczorek W (2010). "Detailed studies on the fillers modification and their influence on composite, poly(oxyethylene)-based polymeric electrolytes".Electrochimica Acta.55(4): 1314–1322.doi:10.1016/j.electacta.2009.04.025.ISSN0013-4686.
  32. ^Syzdek J, Armand M, Gizowska M, Marcinek M, Sasim E, Szafran M, Wieczorek W (2009). "Ceramic-in-polymer versus polymer-in-ceramic polymeric electrolytes—A novel approach".Journal of Power Sources.194(1): 66–72.Bibcode:2009JPS...194...66S.doi:10.1016/j.jpowsour.2009.01.070.ISSN0378-7753.
  33. ^ Jiangshui Luo, Olaf Conrad, Ivo F. J. Vankelecom (2013)."Imidazolium methanesulfonate as a high temperature proton conductor".Journal of Materials Chemistry A.1(6): 2238–2247.doi:10.1039/C2TA00713D.S2CID96622511.
[edit]
Retrieved from "https://en.wikipedia.org/w/index.php?title=Electrolyte&oldid=1244986889"