Editing Voltaic pile

{{Short description|First electrical battery that could continuously provide an electric current to a circuit}}
{{More footnotes needed|date=December 2010}}
[[file:Voltaic pile.svg|upright=1.2|thumb|Schematic diagram of a [[copper]]–[[zinc]] voltaic pile. Each copper–zinc pair had a spacer in the middle, made of cardboard or felt soaked in salt water (the electrolyte). Volta's original piles contained an additional zinc disk at the bottom, and an additional copper disk at the top; these were later shown to be unnecessary.]]
[[file:VoltaBattery.JPG|thumb|upright|A voltaic pile on display in the ''[[Tempio Voltiano]]'' (the Volta Temple) near Volta's home in [[Como]], [[Italy]]]]
[[File:Pila di volta.jpg|thumb|Voltaic pile, [[University History Museum, University of Pavia|University History Museum of the University of Pavia]].]]

The '''voltaic pile''' was the first [[Battery (electricity)|electrical battery]] that could continuously provide an electric current to a circuit.<ref name=":0">{{Cite web |title=Battery: Voltaic Pile |url=https://americanhistory.si.edu/collections/nmah_703289 |access-date=2024-05-12 |website=americanhistory.si.edu |language=en}}</ref> It was invented by Italian chemist [[Alessandro Volta]], who published his experiments in 1799.<ref>{{Cite web |date=2024-04-15 |title=Alessandro Volta {{!}} Biography, Facts, Battery, & Invention {{!}} Britannica |url=https://www.britannica.com/biography/Alessandro-Volta |access-date=2024-05-12 |website=www.britannica.com |language=en}}</ref> Its invention can be traced back to an argument between Volta and [[Luigi Galvani]], Volta's fellow Italian scientist who had conducted experiments on frogs' legs.<ref name=":1">{{Cite web |title=The Voltaic Pile {{!}} Distinctive Collections Spotlights |url=https://libraries.mit.edu/collections/vail-collection/topics/electricity/the-voltaic-pile/ |access-date=2023-01-24 |website=libraries.mit.edu |language=en-US}}</ref> Use of the voltaic pile enabled a rapid series of other discoveries, including the electrical decomposition ([[electrolysis of water|electrolysis]]) of water into oxygen and hydrogen by [[William Nicholson (chemist)|William Nicholson]] and [[Anthony Carlisle]] (1800), and the discovery or isolation of the chemical elements [[sodium]] (1807), [[potassium]] (1807), [[calcium]] (1808), [[boron]] (1808), [[barium]] (1808), [[strontium]] (1808), and [[magnesium]] (1808) by [[Humphry Davy]].<ref name=Decker /><ref name=Russell>{{cite journal |title=Enterprise and electrolysis... |last=Russell |first=Colin |journal=Chemistry World |date=August 2003 |url=http://www.rsc.org/chemistryworld/Issues/2003/August/electrolysis.asp}}</ref>

The entire 19th-century electrical industry was powered by batteries related to Volta's (e.g. the [[Daniell cell]] and [[Grove cell]]) until the advent of the [[dynamo]] (the electrical generator) in the 1870s.<ref>{{Cite web |date=2024-04-15 |title=Alessandro Volta {{!}} Biography, Facts, Battery, & Invention {{!}} Britannica |url=https://www.britannica.com/biography/Alessandro-Volta |access-date=2024-05-12 |website=www.britannica.com |language=en}}</ref>

== History ==
{{main|History of the battery#Invention}}
Volta's invention was built on [[Luigi Galvani]]'s 1780s discovery that a circuit of two metals and a frog's leg can cause the frog's leg to respond.<ref name=":0" /> Volta demonstrated in 1794 that when two metals and [[brine]]-soaked cloth or cardboard are arranged in a circuit they too produce an electric current. In 1800, Volta stacked several pairs of alternating [[copper]] (or [[silver]]) and [[zinc]] discs ([[electrode]]s) separated by cloth or cardboard soaked in brine, which increased the total electromotive force.<ref>{{Cite journal |last=Brockman |first=C. J. |date=June 1927 |title=Primary cells—A brief historical sketch |url=https://pubs.acs.org/doi/abs/10.1021/ed004p770 |journal=[[Journal of Chemical Education]] |language=en |volume=4 |issue=6 |pages=770 |doi=10.1021/ed004p770 |issn=0021-9584}}</ref><ref name="Mottelay">{{cite book |title=Bibliographical History of Electricity and Magnetism |first=Paul Fleury |last=Mottelay |page=247 |url=https://books.google.com/books?id=9vzti90Q8i0C&pg=PA247 |isbn=978-1-4437-2844-7 |publisher=Read Books |year=2008 |edition=Reprint of 1892}}</ref> When the top and bottom contacts were connected by a wire, an electric [[Current (electricity)|current]] flowed through the voltaic pile and the connecting wire. This was the first "true" battery, that gave off continuous charge.<ref name=":12">{{Cite web |title=The Voltaic Pile {{!}} Distinctive Collections Spotlights |url=https://libraries.mit.edu/collections/vail-collection/topics/electricity/the-voltaic-pile/ |access-date=2023-01-24 |website=libraries.mit.edu |language=en-US}}</ref>

Many scientific instruments that belonged to [[Alessandro Volta]] are preserved in the [[University History Museum, University of Pavia|University History Museum of the University of Pavia]], where Volta taught from 1778 to 1819; the piles on display, unfortunately, are not original, as the ones preserved in Pavia were lent on the occasion of the centenary of the invention and subsequently lost in a fire.<ref>{{cite web|url=https://museoperlastoria.unipv.it/en/alessandro-volta-2/|title=Sala Volta|work=Musei Unipv|access-date=21 August 2022}}</ref>

== Applications ==
[[file:Volta batteries.jpg|thumb|upright=1.2|Drawing of the voltaic pile in different configurations, from the letter sent from [[Alessandro Volta]] to [[Joseph Banks]].]]<!--Credit: User:Daniele Pugliesi/Sandbox/1, unpublished work !? Found by serendipity when first editing the page of [[Carl Gassner]]-->

On 20 March 1800, [[Alessandro Volta]] wrote to the [[London]] [[Royal Society]] to describe the technique for producing electric current using his device.<ref name=Volta>{{cite journal |title=On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds |language=fr |first=Alessandro |last=Volta |journal=Philosophical Transactions of the Royal Society of London |volume=90 |pages=403–431 |year=1800 |doi=10.1098/rstl.1800.0018 |doi-access=free }} A partial translation of this paper is available online; see {{cite web |title=Volta and the Battery |url=http://www.chemteam.info/Chem-History/Volta-1800.html |access-date=2012-12-01 }} A complete translation was published in {{cite book |last=Dibner |first=Bern |title=Alessandro Volta and the Electric Battery |publisher=Franklin Watts |year=1964 |pages=111–131 |oclc=247967}}</ref> On learning of the voltaic pile, [[William Nicholson (chemist)|William Nicholson]] and [[Anthony Carlisle]] used it to discover the [[electrolysis]] of water. [[Humphry Davy]] showed that the [[electromotive force]], which drives the electric current through a circuit containing a single voltaic cell, was caused by a chemical reaction, not by the voltage difference between the two metals. He also used the voltaic pile to decompose chemicals and to produce new chemicals. [[William Hyde Wollaston]] showed that electricity from voltaic piles had identical effects to those of electricity produced by [[friction]]. In 1802 [[Vasily Vladimirovich Petrov|Vasily Petrov]] used voltaic piles in the discovery and research of [[electric arc]] effects.

[[Humphry Davy]] and [[Andrew Crosse]] were among the first to develop large voltaic piles.<ref>Encyclopædia Britannica, 1911 edition, Volume V09, Page 185</ref> Davy used a 2000-pair pile made for the [[Royal Institution]] in 1808 to demonstrate carbon [[arc discharge]]<ref>[http://www.osti.gov/bridge/servlets/purl/823202-DHllYA/native/823202.pdf Tracking Down the Origin of Arc Plasma Science. II. Early Continuous Discharges]</ref> and isolate five new elements: barium, calcium, boron, strontium and magnesium.<ref name="Kenyon">{{cite journal|last1=Kenyon|first1=T. K.|title=Science and Celebrity: Humphry Davy's Rising Star |journal=Chemical Heritage Magazine |date=2008|volume=26 |issue=4|pages=30–35|url=https://www.sciencehistory.org/distillations/magazine/science-and-celebrity-humphry-davys-rising-star|access-date=22 March 2018}}</ref>

== Electrochemistry ==

Because Volta believed that the electromotive force occurred at the contact between the two metals, Volta's piles had a different design than the modern design illustrated on this page. His piles had one extra disc of copper at the top, in contact with the zinc, and one extra disc of zinc at the bottom, in contact with the copper.<ref>{{cite journal|last1=Cecchini|first1=R.|last2=Pelosi|first2=G.|title=Alessandro Volta and his battery|journal=IEEE Antennas and Propagation Magazine|date=April 1992|volume=34|issue=2|pages=30–37|doi=10.1109/74.134307|bibcode=1992IAPM...34...30C|s2cid=6515671}}</ref> Expanding on Volta's work and the electro-magnetism work of his mentor [[Humphry Davy]], [[Michael Faraday]] utilized both magnets and the voltaic pile in his experiments with electricity. Faraday believed that all "electricities" being studied at the time (voltaic, magnetic, thermal, and animal) were one and the same. His work to prove this theory led him to propose two laws of electrochemistry which stood in direct conflict with the current scientific beliefs of the day as laid down by Volta thirty years earlier.<ref>{{cite book |last1=James |first1=Frank A. J. L. |chapter-url=https://archive.org/details/electrochemistry0000unse_m6a2/page/32/mode/2up|title=Electrochemistry, past and present |date=1989 |publisher=American Chemical Society |isbn=9780841215726 |editor1-last=Stock |editor1-first=J. T. |location=Washington, DC |pages=32–49 |chapter=Michael Faraday's first law of electrochemistry: how context develops new knowledge |editor2-last=Orna |editor2-first=M. V. |chapter-format=}}</ref> Because of their contributions to the understanding of this field of study, Faraday and Volta are both considered to be among the fathers of [[electrochemistry]].<ref>{{cite book |last1=Stock |first1=John T. |title=Electrochemistry, past and present |date=1989 |publisher=American Chemical Society |isbn=9780841215726 |editor1-last=Orna |editor1-first=Mary Virginia |location=Washington, DC |pages=1–17 |chapter=Electrochemistry in retrospect: an overview |chapter-format=}}</ref> The words "electrode" and "electrolyte", used above to describe Volta's work, are due to Faraday.<ref>{{cite journal|last1=James|first1=F.A.J.L.|title=The Royal Institution of Great Britain: 200 years of scientific discovery and communication|journal=Interdisciplinary Science Reviews|date=18 July 2013|volume=24|issue=3|pages=225–231|doi=10.1179/030801899678777}}</ref>

== Electromotive force ==

The strength of the pile is expressed in terms of its [[electromotive force]], or emf, given in volts. Alessandro Volta's theory of [[contact tension]] considered that the emf, which drives the electric current through a circuit containing a voltaic cell, occurs at the contact between the two metals. Volta did not consider the electrolyte, which was typically [[brine]] in his experiments, to be significant. However, chemists soon realized that water in the electrolyte was involved in the pile's chemical reactions, and led to the evolution of [[hydrogen]] gas from the copper or silver electrode.<ref name=Decker>{{cite encyclopedia |last=Decker |first=Franco |encyclopedia=Electrochemistry Encyclopedia |title=Volta and the 'Pile' |date=January 2005 |publisher=Case Western Reserve University |url=http://electrochem.cwru.edu/encycl/art-v01-volta.htm |url-status=dead |archive-url=https://web.archive.org/web/20120716205546/http://electrochem.cwru.edu/encycl/art-v01-volta.htm |archive-date=2012-07-16 }}</ref><ref name=Turner>{{cite book |title=Elements of chemistry: including the actual state and prevalent doctrines of the science |first1=Edward |last1=Turner |editor1-first=Justus |editor1-last=Liebig |editor2-first=William |editor2-last=Gregory |edition=7|publisher=Taylor and Walton |location=London |year=1841 |page=102 |url=https://books.google.com/books?id=pRPnAAAAMAAJ&pg=PA102 |quote=During the action of a simple circle, as of zinc and copper, excited by dilute sulfuric acid, all of the hydrogen developed in the voltaic action is evolved at the surface of the copper.}}</ref><ref name=Goodisman>{{cite journal |last=Goodisman |first=Jerry |title=Observations on Lemon Cells |journal=Journal of Chemical Education |year=2001 |volume=78 |issue=4 |pages=516 |url=http://surface.syr.edu/cgi/viewcontent.cgi?article=1001&context=che |doi=10.1021/ed078p516|bibcode=2001JChEd..78..516G }} Goodisman notes that many chemistry textbooks use an incorrect model for a cell with zinc and copper electrodes in an acidic electrolyte.</ref><ref name=Graham>{{cite book |title=The Geek Atlas: 128 Places Where Science and Technology Come Alive |first=John |last=Graham-Cumming |chapter=Tempio Voltiano |publisher=O'Reilly Media |year=2009 |isbn=9780596523206 |page=97 |chapter-url=https://books.google.com/books?id=HhEC0q-O1ewC&pg=PA97}}</ref>

The modern, atomistic understanding of a cell with zinc and copper electrodes separated by an electrolyte is the following. When the cell is providing an electrical current through an external circuit, the metallic zinc at the surface of the zinc anode is oxidized and dissolves into the electrolyte as electrically charged [[ions]] (Zn<sup>2+</sup>), leaving two negatively charged [[electron]]s ({{SubatomicParticle|electron}}) behind in the metal:

::[[anode]] (oxidation): Zn{{space|2}}{{arrow2|right|11px}}{{space|2}}Zn<sup>2+</sup> + 2 {{SubatomicParticle|electron}}

This reaction is called [[redox|oxidation]]. While zinc is entering the electrolyte, two positively charged [[hydrogen]] ions (H<sup>+</sup>) from the electrolyte accept two electrons at the copper cathode surface, become reduced and form an uncharged hydrogen molecule (H<sub>2</sub>):

::[[cathode]] (reduction): 2 H<sup>+</sup> + 2 {{SubatomicParticle|electron}}{{space|2}}{{arrow2|right|11px}}{{space|2}}H<sub>2</sub>

This reaction is called [[redox|reduction]]. The electrons used from the copper to form the molecules of hydrogen are made up by an external wire or circuit that connects it to the zinc. The hydrogen molecules formed on the surface of the copper by the reduction reaction ultimately bubble away as hydrogen gas.

One will observe that the global electro-chemical reaction does not immediately involve the electrochemical couple Cu<sup>2+</sup>/Cu (Ox/Red) corresponding to the copper cathode. The copper metal disk thus only serves here as a "chemically inert" noble metallic conductor for the transport of electrons in the circuit and does not chemically participate in the reaction in the aqueous phase. Copper does act as a catalyst for the hydrogen-evolution reaction, which otherwise could occur equally well directly at the zinc electrode without current flow through the external circuit. The copper electrode could be replaced in the system by any sufficiently noble/inert and catalytically active metallic conductor (Ag, Pt, stainless steel, graphite, ...). The global reaction can be written as follows:

::Zn + 2H<sup>+</sup>{{space|2}}{{arrow2|right|11px}}{{space|2}}Zn<sup>2+</sup> + H<sub>2</sub>

This is usefully stylized by means of the electro-chemical chain notation:

::(anode: oxidation) Zn | Zn<sup>2+</sup> || 2H<sup>+</sup> | H<sub>2</sub> | Cu (cathode: reduction)

in which a vertical bar each time represents an interface. The double vertical bar represents the interfaces corresponding to the electrolyte impregnating the porous cardboard disk.

When no current is drawn from the pile, each cell, consisting of zinc/electrolyte/copper, generates 0.76 V with a brine electrolyte. The voltages from the cells in the pile add, so the six cells in the diagram above generate 4.56 V of electromotive force.

== Dry piles ==

A number of high-voltage ''dry piles'' were invented between 1800 and the 1830s in an attempt to determine the source of [[electricity]] of the wet voltaic pile, and specifically to support Volta's hypothesis of contact tension. Indeed, Volta himself experimented with a pile whose cardboard discs had dried out, most likely accidentally.

The first to publish the discovery of a dry pile that produced a current was [[Johann Wilhelm Ritter]] in 1802, albeit in an obscure journal; over the next decade, it was announced repeatedly as a new discovery. One form of dry pile is the [[Zamboni pile]]. [[Francis Ronalds]] in 1814 was one of the first to realize that dry piles also worked through chemical reaction rather than metal-to-metal contact, even though corrosion was not visible due to the very small currents generated.<ref>{{Cite book|title=Sir Francis Ronalds: Father of the Electric Telegraph|last=Ronalds|first=B.F.|publisher=Imperial College Press|year=2016|isbn=978-1-78326-917-4|location=London}}</ref><ref>{{Cite journal|last=Ronalds|first=B.F.|date=July 2016|title=Francis Ronalds (1788-1873): The First Electrical Engineer?|journal=Proceedings of the IEEE|volume=104|issue=7|pages=1489–1498|doi=10.1109/JPROC.2016.2571358|s2cid=20662894}}</ref>

The dry pile could be referred to as the ancestor of the modern [[dry cell]].{{original research inline|date=January 2022}}

== See also ==
{{Portal|Electronics}}

* [[List of battery types]]
* [[Salt water battery]]
* [[Aqueous lithium-ion battery]]
* [[Volta potential]]

== References ==

{{reflist}}

== External links ==
{{Commons category}}

*{{cite web |url=http://www.magnet.fsu.edu/education/tutorials/java/voltaicpile1/index.html |title=Voltaic Pile Tutorial |publisher=National High Magnetic Field Laboratory}}
* "''[http://physics.kenyon.edu/EarlyApparatus/Electricity/Voltaic_Pile/Voltaic_Pile.html The Voltaic Pile]''". Electricity. Kenyon.edu.
* Lewis, Nancy D., "''[http://fargo.itp.tsoa.nyu.edu/~lewis/electricity/pages/volta.html Alesandro Volta The Voltaic Pile]''".
* Lewis, Nancy D., "''[http://fargo.itp.tsoa.nyu.edu/~lewis/electricity/pages/davy.html Humphry Davy Electrochemistry]''".

{{Galvanic cells}}
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[[Category:Battery types]]
[[Category:Alessandro Volta]]