Alessandro Volta

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Alessandro Volta
Volta A.jpg
Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta
Born 18 February 1745
Como, Duchy of Milan
(present-day Italy)
Died 5 March 1827(1827-03-05) (aged 82)
Como, Lombardy-Venetia
(present-day Italy)
Known for Invention of the electric cell
Discovery of methane
volt
Voltage
Voltmeter
Scientific career
Fields Physics & Chemistry

Count Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta (18 February 1745 – 5 March 1827) was an Italian[1][2] physicist known especially for the invention of the battery in the 1800s.

Early life and works

Volta was born in Como, Italy on 18 February 1745. In 1774, he became a physics professor at the Royal School in Como. A year later, he improved and popularized the electrophorus, a device that produced a static charge. His promotion of it was so extensive that he is often credited with its invention, even though a machine operating in the same principle was described in 1762 by Swedish professor Johan Wilcke.[3]

In the years between 1776–78, Volta studied the chemistry of gases. He discovered methane after reading a paper by Benjamin Franklin on "flammable air" and carefully searched for it in Italy. In November, 1776, he found methane at Lake Maggiore, and by 1778 he managed to isolate methane.[4] He devised experiments such as the ignition of methane by an electric spark in a closed vessel. Volta also studied what we now call electrical capacitance, developing separate means to study both electrical potential (V) and charge (Q), and discovering that for a given object, they are proportional. This may be called Volta's Law of capacitance, and likely for this work the unit of electrical potential has been named the volt.

In 1779 he became professor of experimental physics at the University of Pavia, a chair he occupied for almost 25 years. In 1794, Volta married an aristocratic lady also from Como, Teresa Peregrini, with whom he raised three sons: Giovanni, Flaminio and Zanino.[5]

Volta and Galvani

Luigi Galvani

The "animal electricity" noted by Luigi Galvani when two different metals were connected in series with the frog's leg and to one another. Volta realized that the frog's leg served as both a conductor of electricity (we would now call it an electrolyte) and as a detector of electricity. He replaced the frog's leg with brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies. In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference between their two electrode potentials (thus, two identical electrodes and a common electrolyte give zero net emf). This may be called Volta's Law of the electrochemical series.

In 1800, as the result of a professional disagreement over the galvanic response advocated by Galvani, he invented the voltaic pile, an early electric battery, which produced a steady electric current.[6] Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The voltaic pile replaced the goblets with cardboard soaked in brine.

First battery

In announcing his discovery of the pile, Volta paid tribute to the influences of William Nicholson, Tiberius Cavallo and Abraham Bennet.[7]

Voltaic pile

The battery made by Volta is credited as the first electrochemical cell. It consists of two electrodes: one made of zinc, the other of copper. The electrolyte is sulfuric acid or a brine mixture of carbon and water. The electrolyte exists in the form 2H+ and SO42−. The zinc, which is higher than both copper and hydrogen in the electrochemical series, reacts with the negatively charged sulfate (SO42−). The positively charged hydrogen ions (protons) capture electrons from the copper, forming bubbles of hydrogen gas, H2. This makes the zinc rod the negative electrode and the copper rod the positive electrode.

We now have two terminals, and the current will flow if we connect them. The reactions in this cell are as follows:

zinc
Zn Zn2+ + 2e
sulfuric acid
2H+ + 2e H2

The copper does not react, functioning as an electrode for the chemical reaction.

However, this cell also has some disadvantages. It is unsafe to handle, as sulfuric acid, even if dilute, is dangerous. Also, the power of the cell diminishes over time because the hydrogen gas is not released, accumulating instead on the surface of the zinc electrode and forming a barrier between the metal and the electrolyte solution.

Last years and retirement

Volta explains the principle of the "electric column" to Napoleon

In honor of his work, Volta was made a count by Napoleon in 1801.[8] Furthermore, he was depicted upon the Italian 10,000 Lire (no longer in circulation) along with a sketch of his famous Voltaic Pile.

Volta retired in 1819 to his estate in Camnago, a frazione of Como now called Camnago Volta after him, where he died on 5 March 1827.[9] He is buried in Camnago Volta.[10]

Volta's legacy is celebrated by a Temple located in the public gardens by the lake. There is also a museum which has been built in his honor and exhibits some of the original equipment he used to conduct experiments; not far away stands the Villa Olmo, which houses the Voltian Foundation, an organization promoting scientific activities. Volta carried out his experimental studies and made his first inventions in Como.

Possible earlier batteries

Drawing of the Baghdad Battery.[11]

Recently there is a growing dispute over the invention of the battery. It has been suggested that the Baghdad battery discovered by Wilhelm Konig in 1938 at Khujut Rabu near Baghdad has priority. The Baghdad battery may have been used by Persians some 2000 years ago for electroplating and may be the first known chemical battery.[12][unreliable source?][13][unreliable source?]

Publications

De vi attractiva ignis electrici (1769) (On the attractive force of electric fire)

See also

References

  1. Giuliano Pancaldi, "Volta: Science and culture in the age of enlightenment", Princeton University Press, 2003.
  2. Alberto Gigli Berzolari, "Volta's Teaching in Como and Pavia"- Nuova voltiana
  3. Pancaldi, Giuliano (2003). Volta, Science and Culture in the Age of Enlightenment. Princeton Univ. Press. ISBN 978-0-691-12226-7. , p.73
  4. "Methane". BookRags. Retrieved 26 January 2012. 
  5. Munro, John (1902). Pioneers of Electricity; Or, Short Lives of the Great Electricians. London: The Religious Tract Society. pp. 89–102. 
  6. Robert Routledge (1881). A popular history of science (2nd ed.). G. Routledge and Sons. p. 553. ISBN 0-415-38381-1. 
  7. Elliott, P. (1999). "Abraham Bennet F.R.S. (1749-1799): a provincial electrician in eighteenth-century England" (PDF). Notes and Records of the Royal Society of London. 53 (1): 59–78. doi:10.1098/rsnr.1999.0063. 
  8. "Alessandro Volta". IEEE Global History Network. IEEE. Retrieved 21 July 2011. 
  9. "Volta". Institute of Chemistry - Jerusalem. Retrieved 2009-05-01. 
  10. For a photograph of his gravesite, and other Volta locales, see "Volta's localities". Retrieved 2009-06-20. [dead link]
  11. "Paranormal Image Gallery - Ancient Mysteries/Aztec carving of ancient astronaut". Unexplained Mysteries. Retrieved 2009-11-14. 
  12. The Baghdad Battery, The Museum of UnNatural Mystery
  13. World Mysteries.com

External links

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