Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (a metal or a semiconductor) and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called In Chemistry, a solution is a Homogeneous Mixture composed of two or more substances In Science and engineering, a conductor is a material which contains movable Electric charges. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium

If a chemical reaction is driven by an external applied voltage, as in electrolysis, or if a voltage is created by a chemical reaction and as in a battery, it is an electrochemical reaction. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy Chemical reactions where electrons are transferred between molecules are called oxidation/reduction (redox) reactions. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state In general, electrochemistry deals with situations where oxidation and reduction reactions are separated in space or time, connected by an external electric circuit to understand each process. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state

Contents 1 History 1.1 16th to 18th century developments 1.2 19th century 1.3 The 20th century and recent developments 2 Principles 2.1 Redox reactions 2.2 Oxidation and reduction 2.3 Balancing redox reactions 2.3.1 Acid medium 2.3.2 Basic medium 2.3.3 Neutral medium 3 Electrochemical cells 4 Standard electrode potential 5 Spontaneity of Redox reaction 6 Cell emf dependency on changes in concentration 6.1 Nernst Equation 6.2 Concentration cells 7 Battery 7.1 Dry cell 7.2 Mercury battery 7.3 Lead-acid battery 7.4 Lithium rechargeable battery 7.5 Flow battery/ Redox flow battery 7.6 Fuel cells 8 Corrosion 8.1 Iron corrosion 8.2 Corrosion of common metals 8.3 Prevention of corrosion 8.3.1 Coating 8.3.2 Sacrificial anodes 9 Electrolysis 9.1 Electrolysis of molten sodium chloride 9.2 Electrolysis of water 9.3 Electrolysis of aqueous solutions 9.3.1 Electrolysis of a solution of sodium chloride 9.4 Quantitative electrolysis & Faraday's Laws 9.4.1 First law 9.4.2 Second law 10 Applications 11 See also 12 References 13 External links

History

Main article: History of electrochemistry

16th to 18th century developments

The 16th century marked the beginning of electrical understanding. During that century the English scientist William Gilbert spent 17 years experimenting with magnetism and, to a lesser extent, electricity. William Gilbert, also known as Gilbard ( Colchester, England, May 24, 1544 &ndash London, England, November 30 In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. For his work on magnets, Gilbert became known as the "Father of Magnetism. " He discovered various methods for producing and strengthening magnets.

In 1663 the German physicist Otto von Guericke created the first electric generator, which produced static electricity by applying friction in the machine. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning Otto von Guericke (originally spelled Gericke ˈgeːʁɪkə ( November 20, 1602 &ndash May 11, 1686 ( Julian calendar) The generator was made of a large sulfur ball cast inside a glass globe, mounted on a shaft. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 The ball was rotated by means of a crank and a static electric spark was produced when a pad was rubbed against the ball as it rotated. For the science of static charges see Electrostatics Static electricity refers to the accumulation of excess Electric charge in a The globe could be removed and used as source for experiments with electricity.

By the mid—18th century the French chemist Charles François de Cisternay du Fay discovered two types of static electricity, and that like charges repel each other whilst unlike charges attract. This article is about the country For a topic outline on this subject see List of basic France topics. A chemist is a Scientist trained in the Science of Chemistry. Charles François de Cisternay du Fay (Paris 14 September[[ 698]] &ndash 1739 was a French Chemist and superintendent of the Jardin du Roi. Du Fay announced that electricity consisted of two fluids: "vitreous" (from the Latin for "glass"), or positive, electricity; and "resinous," or negative, electricity. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. This was the two-fluid theory of electricity, which was to be opposed by Benjamin Franklin's one-fluid theory later in the century. Benjamin Franklin ( April 17 1790 was one of the Founding Fathers of the United States of America.

Charles-Augustin de Coulomb developed the law of electrostatic attraction in 1781 as an outgrowth of his attempt to investigate the law of electrical repulsions as stated by Joseph Priestley in England. Charles Augustin de Cock (June 14 1736 Angoulême France – August 23 1806 Penis France was a French Physicist. Electrostatics is the branch of Science that deals with the Phenomena arising from what seems to be stationary Electric charges Since Classical Joseph Priestley (13 March 1733 ( Old

In the late 18th century the Italian physician and anatomist Luigi Galvani marked the birth of electrochemistry by establishing a bridge between chemical reactions and electricity on his essay "De Viribus Electricitatis in Motu Musculari Commentarius" (Latin for Commentary on the Effect of Electricity on Muscular Motion) in 1791 where he proposed a "nerveo-electrical substance" on biological life forms. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest A physician, medical practitioner or medical doctor who practices Medicine, and is concerned with maintaining or restoring human Health Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration Luigi Galvani was an Italian Physician and Physicist who lived and died in Bologna.

In his essay Galvani concluded that animal tissue contained a here-to-fore neglected innate, vital force, which he termed "animal electricity," which activated nerves and muscles spanned by metal probes. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. Muscle (from Latin musculus, diminutive of mus "mouse" is contractile tissue of the body and is derived from the The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across He believed that this new force was a form of electricity in addition to the "natural" form produced by lightning or by the electric eel and torpedo ray as well as the "artificial" form produced by friction (i. Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or The electric eel, Electrophorus electricus, is a species of Fish. Electric rays (order Torpediniformes) are Fish that have a rounded body and a pair of organs capable of producing an Electric discharge, varying Friction is the Force resisting the relative motion of two Surfaces in contact or a surface in contact with a fluid (e e. , static electricity).

Galvani's scientific colleagues generally accepted his views, but Alessandro Volta rejected the idea of an "animal electric fluid," replying that the frog's legs responded to differences in metal temper, composition, and bulk. Tempering is a Heat treatment technique for metals and Alloys In Steels tempering is done to "toughen" the metal by transforming brittle Galvani refuted this by obtaining muscular action with two pieces of the same material.

19th century

In 1800, William Nicholson and Johann Wilhelm Ritter succeeded in decomposing water into hydrogen and oxygen by electrolysis. William Nicholson (1753&mdash May 21, 1815) was a renowned English chemist who was also a writer on natural philosophy and chemistry as well as a translator Johann Wilhelm Ritter ( December 16, 1776 – January 23, 1810) was a German Chemist and Physicist. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current Soon thereafter Ritter discovered the process of electroplating. Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object He also observed that the amount of metal deposited and the amount of oxygen produced during an electrolytic process depended on the distance between the electrodes. An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e By 1801 Ritter observed thermoelectric currents and anticipated the discovery of thermoelectricity by Thomas Johann Seebeck. Thermoelectricity ( Thermo - Electricity) refers to a class of phenomena in which a Temperature difference creates an Electric potential or an electric Thomas Johann Seebeck ( April 9 1770 &ndash December 10 1831) was a physicist who in 1821 discovered the Thermoelectric effect

By the 1810s William Hyde Wollaston made improvements to the galvanic pile. William Hyde Wollaston FRS ( August 6, 1766 &ndash December 22, 1828) was an English Chemist and physicist Sir Humphry Davy's work with electrolysis led to the conclusion that the production of electricity in simple electrolytic cells resulted from chemical action and that chemical combination occurred between substances of opposite charge. Sir Humphry Davy 1st Baronet FRS MRIA (17 December 1778 &ndash 29 May 1829 was a British Chemist and inventor An electrolytic cell decomposes chemical compounds by means of electrical energy in a process called Electrolysis; the Greek word Lysis means to break up This work led directly to the isolation of sodium and potassium from their compounds and of the alkaline earth metals from theirs in 1808. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 Biological occurrences Beryllium's low aqueous solubility means it is rarely available to biological systems it has no known role in living organisms and when encountered

Hans Christian Ørsted's discovery of the magnetic effect of electrical currents in 1820 was immediately recognized as an epoch-making advance, although he left further work on electromagnetism to others. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of André-Marie Ampère quickly repeated Ørsted's experiment, and formulated them mathematically. André-Marie Ampère (20 January 1775 &ndash 10 June 1836 was a French Physicist and Mathematician who is generally credited as one of the main discoverers

In 1821, Estonian-German physicist Thomas Johann Seebeck demonstrated the electrical potential in the juncture points of two dissimilar metals when there is a heat difference between the joints. A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning Thomas Johann Seebeck ( April 9 1770 &ndash December 10 1831) was a physicist who in 1821 discovered the Thermoelectric effect In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature

In 1827 the German scientist Georg Ohm expressed his law in this famous book "Die galvanische Kette, mathematisch bearbeitet" (The Galvanic Circuit Investigated Mathematically) in which he gave his complete theory of electricity. Georg Simon Ohm' was a German physicist As a high school teacher Ohm began his research with the recently invented Electrochemical cell, invented by Italian Count Ohm's law applies to Electrical circuits it states that the current through a conductor between two points is directly proportional to the

In 1832 Michael Faraday's experiments led him to state his two laws of electrochemistry. Michael Faraday, FRS ( September 22 1791 – August 25 1867) was an English In 1836 John Daniell invented a primary cell in which hydrogen was eliminated in the generation of the electricity. John Frederic Daniell ( 12 March 1790 &ndash 13 March 1845) was an English Chemist and Physicist. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Daniell had solved the problem of polarization. In his laboratory he had learned that alloying the amalgamated zinc of Sturgeon with mercury would produce a better voltage. An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum

William Grove produced the first fuel cell in 1839. Sir William Robert Grove PC QC FRS ( 11 July, 1811 &ndash 1 August, 1896) was a British Lawyer A fuel cell is an electrochemical conversion device It produces electricity from Fuel (on the Anode side and an oxidant (on the In 1846, Wilhelm Weber developed the electrodynamometer. Wilhelm Eduard Weber ( October 24, 1804 &ndash June 23, 1891) was a German Physicist. The wattmeter is an instrument for measuring the Electric power (or the supply rate of Electrical energy) in Watts of any given circuit. In 1866, Georges Leclanché patented a new cell which eventually became the forerunner to the world's first widely used battery, the zinc carbon cell. Georges Leclanché ( 1839 - September 14, 1882) was a French electrical engineer chiefly remembered for his invention of the Leclanché cell, A Zinc-carbon Dry cell or battery is packaged in a Zinc can that serves as both a container and anode

Svante August Arrhenius published his thesis in 1884 on Recherches sur la conductibilité galvanique des électrolytes (Investigations on the galvanic conductivity of electrolytes). Svante August Arrhenius ( February 19, 1859 &ndash October 2, 1927) was a Swedish Scientist, originally a Physicist From his results the author concluded that electrolytes, when dissolved in water, become to varying degrees split or dissociated into electrically opposite positive and negative ions. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium

In 1886 Paul Héroult and Charles M. Hall developed a successful method to obtain aluminium by using the principles described by Michael Faraday. The French scientist Paul ( Louis-Toussaint) Héroult ( April 10 1863 – May 9 1914) was the inventor of the Aluminium Charles Martin Hall ( December 6, 1863 – December 27, 1914) was an American inventor and engineer WikipediaNaming

In 1894 Friedrich Ostwald concluded important studies of the electrical conductivity and electrolytic dissociation of organic acids. Friedrich Wilhelm Ostwald ( Latvian: Vilhelms Ostvalds; September 2, 1853 &ndash April 4, 1932) was a Baltic Electrical conductivity or specific conductivity is a measure of a material's ability to conduct an Electric current. An organic acid is an Organic compound with Acidic properties

Walther Hermann Nernst developed the theory of the electromotive force of the voltaic cell in 1888. Walther Hermann Nernst ( June 25, 1864 &ndash November 18, 1941) was a German Physicist who is known for his theories Electromotive force ( emf, \mathcal{E} is a term used to characterize electrical devices such as Voltaic cells thermoelectric devices electrical In 1889, he showed how the characteristics of the current produced could be used to calculate the free energy change in the chemical reaction producing the current. In Thermodynamics, the term thermodynamic free energy refers to the amount of work that can be extracted from a System, and is helpful in Engineering He constructed an equation, known as Nernst Equation, which related the voltage of a cell to its properties. In Electrochemistry, the Nernst equation is an equation which can be used (in conjunction with other information to determine the equilibrium Reduction potential

In 1898 Fritz Haber showed that definite reduction products can result from electrolytic processes if the potential at the cathode is kept constant. Fritz Haber (9 December 1868 &ndash 29 January 1934 was a German chemist, who received the Nobel Prize in Chemistry in 1918 for his development for A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device In 1898 he explained the reduction of nitrobenzene in stages at the cathode and this became the model for other similar reduction processes. Nitrobenzene, also known as nitrobenzol or oil of mirbane, is an Organic compound with the Chemical formula C 6

The 20th century and recent developments

In 1902, The Electrochemical Society (ECS) was founded. The Electrochemical Society (ECS is a Learned society ( Professional association) based in the United States that supports scientific inquiry in the field

In 1909, Robert Andrews Millikan began a series of experiments to determine the electric charge carried by a single electron. Robert Andrews Millikan (March 22 1868 – December 19 1953 was an American experimental physicist, and Nobel laureate in physics for his measurement The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J

In 1923, Johannes Nicolaus Brønsted and Thomas Martin Lowry published essentially the same theory about how acids and bases behave, using an electrochemical basis. Johannes Nicolaus Brønsted born in Varde ( February 22, 1879 – December 17, 1947) was a Danish physical chemist Thomas Martin Lowry ( October 26, 1874 - November 2, 1936) was an English physical chemist.

Arne Tiselius developed the first sophisticated electrophoretic apparatus in 1937 and some years later he was awarded the 1948 Nobel Prize for his work in protein electrophoresis. Arne Wilhelm Kaurin Tiselius ( 10 August 1902 &ndash 29 October 1971) was a Swedish Biochemist who won the Nobel Prize Electrophoresis is the most well-known electrokinetic phenomenon. The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature Electrophoresis is the most well-known electrokinetic phenomenon.

A year later, in 1949, the International Society of Electrochemistry (ISE) was founded. The International Society of Electrochemistry (ISE is a global scientific society founded in 1949.

By the 1960s–1970s quantum electrochemistry was developed by Revaz Dogonadze and his pupils. The scientific school of Quantum electrochemistry began to form in the 1960s under Revaz Dogonadze. Revaz Dogonadze ( November 21, 1931 - May 13, 1985) was a notable Georgian

Principles

Redox reactions

Main article: Redox reaction

Electrochemical processes involve redox reactions where an electron is transferred to or from a molecule or ion changing its oxidation state. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. This reaction can occur through the application of an external voltage or through the release of chemical energy. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical

Oxidation and reduction

The atoms, ions, or molecules involved in an electrochemical reaction are characterized by the number of electrons each has compared to its number of protons called its oxidation state and is denoted by a + or a -. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive Thus the superoxide ion, O₂^-, has an oxidation state of -1. An atom or ion that gives up an electron to another atom or ion has its oxidation state increase, and the recipient of the negatively charged electron has its oxidation state decrease. Oxidation and reduction always occur in a paired fashion such that one species is oxidized when another is reduced. This paired electron transfer is called a redox reaction. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state

For example when atomic sodium reacts with atomic chlorine, sodium donates one electron and attains an oxidation state of +1. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Chlorine accepts the electron and its oxidation state is reduced to −1. The sign of the oxidation state (positive/negative) actually corresponds to the value of each ion's electronic charge. The attraction of the differently charged sodium and chlorine ions is the reason they then form an ionic bond. An ionic bond (or electrovalent bond) is a type of Chemical bond that can often form between Metal and Non-metal Ions (or

The loss of electrons from an atom or molecule is called oxidation, and the gain of electrons is reduction. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state This can be easily remembered through the use of mnemonic devices. A mnemonic device (nəˈmɒnɪk is a Memory aid Commonly met mnemonics are often verbal something such as a very short poem or a special word used to help a person remember Two of the most popular are "OIL RIG" (Oxidation Is Loss, Reduction Is Gain) and "LEO" the lion says "GER" (Lose Electrons: Oxidization, Gain Electrons: Reduction). For cases where electrons are shared (covalent bonds) between atoms with large differences in electronegativity, the electron is assigned to the atom with the largest electronegativity in determining the oxidation state. " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons

The atom or molecule which loses electrons is known as the reducing agent, or reductant, and the substance which accepts the electrons is called the oxidizing agent, or oxidant. The oxidizing agent is always being reduced in a reaction; the reducing agent is always being oxidized. Oxygen is a common oxidizing agent, but not the only one. Despite the name, an oxidation reaction does not necessarily need to involve oxygen. In fact, a fire can be fed by an oxidant other than oxygen; fluorine fires are often unquenchable, as fluorine is an even stronger oxidant (it has a higher electronegativity) than oxygen. Fire is the heat and light energy released during a Chemical reaction, in particular a combustion reaction. Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons

For reactions involving oxygen, the gain of oxygen implies the oxidation of the atom or molecule to which the oxygen is added (and the oxygen is reduced). For example, in the oxidation of octane by oxygen to form carbon dioxide and water, both the carbon in the octane and the oxygen begin with an oxidation state of 0. Octane is a straight-chain Alkane with the Chemical formula CH3(CH26CH3 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Water is a common Chemical substance that is essential for the survival of all known forms of Life. In forming CO₂ the carbon loses four electrons to become C⁴⁺ and the oxygens each gain two electrons to be O^2-. In organic compounds, such as butane or ethanol, the loss of hydrogen implies oxidation of the molecule from which it is lost (and the hydrogen is reduced). Butane, also called n -butane, is the unbranched Alkane with four Carbon Atoms CH3CH2CH2CH3 This follows because the hydrogen donates its electron in covalent bonds with non-metals but it takes the electron along when it is lost. Conversely, loss of oxygen or gain of hydrogen implies reduction.

Balancing redox reactions

Main article: Chemical equation

Electrochemical reactions in water are better understood by balancing redox reactions using the Ion-Electron Method where H⁺ , OH^- ion, H₂O and electrons (to compensate the oxidation changes) are added to cell's half reactions for oxidation and reduction. A chemical equation is a symbolic representation of a Chemical reaction. In Chemistry, hydronium is the obsolete name for the Cation H 3 O + derived from Protonation of Water In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as A half reaction is either the oxidation or reduction reaction component of a Redox reaction.

Acid medium

In acid medium H+ ions and water are added to half reactions to balance the overall reaction. In Chemistry, hydronium is the obsolete name for the Cation H 3 O + derived from Protonation of Water A half reaction is either the oxidation or reduction reaction component of a Redox reaction. For example, when manganese reacts with sodium bismuthate. Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn.

Finally the reaction is balanced by multiplying the number of electrons from the reduction half reaction to oxidation half reaction and vice versa and adding both half reactions, thus solving the equation.

Reaction balanced:

Basic medium

In basic medium OH^- ions and water are added to half reactions to balance the overall reaction. In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as For example on reaction between Potassium permanganate and Sodium sulfite. Potassium permanganate is the Chemical compound K[[manganese Mn]] O 4 Sodium sulfite (sodium sulphite is a soluble compound of Sodium.

The same procedure as followed on acid medium by multiplying electrons to opposite half reactions solve the equation thus balancing the overall reaction.

Equation balanced:

Neutral medium

The same procedure as used on acid medium is applied, for example on balancing using electron ion method to complete combustion of propane. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of Propane is a three- Carbon Alkane, normally a gas but compressible to a liquid that is transportable

As in acid and basic medium, electrons which were used to compensate oxidation changes are multiplied to opposite half reactions, thus solving the equation.

Equation balanced:

Electrochemical cells

Main article: Electrochemical cell

An electrochemical cell is a device that produces an electric current from energy released by a spontaneous redox reaction. An electrochemical cell is a device used for generating an Electromotive force ( Voltage) and current from chemical reactions. A spontaneous process is the time-evolution of a system in which it releases free energy (most often as heat and moves to a lower more thermodynamically stable energy state This kind of cell includes the Galvanic cell or Voltaic cell, named after Luigi Galvani and Alessandro Volta, both scientists who conducted several experiments on chemical reactions and electric current during the late 18th century. The Galvanic cell, named after Luigi Galvani, consists of two different metals connected by a Salt bridge or a porous disk between the individual half-cells Luigi Galvani was an Italian Physician and Physicist who lived and died in Bologna.

Electrochemical cells have two conductive electrodes (the anode and the cathode). The anode is defined as the electrode where oxidation occurs and the cathode is the electrode where the reduction takes place. An anode is an Electrode through which Electric current flows into a polarized electrical device A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device Electrodes can be made from any sufficiently conductive materials, such as metals, semiconductors, graphite, and even conductive polymers. Semiconducting and metallic “organic” polymers are based on Sp2 Hybridized linear carbon chains In between these electrodes is the electrolyte, which contains ions that can freely move. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium

The Galvanic cell uses two different metal electrodes, each in an electrolyte where the positively charged ions are the oxidized form of the electrode metal. One electrode will undergo oxidation (the anode) and the other will undergo reduction (the cathode). The metal of the anode will oxidize, going from an oxidation state of 0 (in the solid form) to a positive oxidation state and become an ion. At the cathode, the metal ion in solution will accept one or more electrons from the cathode and the ion's oxidation state is reduced to 0. This forms a solid metal that electrodeposits on the cathode. Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object The two electrodes must be electrically connected to each other, allowing for a flow of electrons that leave the metal of the anode and flow through this connection to the ions at the surface of the cathode. This flow of electrons is an electrical current that can be used to do work, such as turn a motor or power a light.

A Galvanic cell whose electrodes are zinc and copper submerged in zinc sulfate and copper sulfate, respectively, is known as a Daniell cell. An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Zinc sulfate ( Zn[[Sulfate SO4]] is a colorless crystalline water-soluble Chemical compound. Copper(II sulfate is the Chemical compound with the formula Cu[[Sulfur S]] O 4 The Daniell cell (var sp Daniel cell, also called the gravity cell or crowfoot cell was invented in 1836 by John Frederic Daniell, who was

Half reactions for a Daniell cell are these:

In this example, the anode is zinc metal which oxidizes (loses electrons) to form zinc ions in solution, and copper ions accept electrons from the copper metal electrode and the ions deposit at the copper cathode as an electrodeposit. This cell forms a simple battery as it will spontaneously generate a flow of electrical current from the anode to the cathode through the external connection. This reaction can be driven in reverse by applying a voltage, resulting in the deposition of zinc metal at the anode and formation of copper ions at the cathode.

To provide a complete electric circuit, there must also be an ionic conduction path between the anode and cathode electrolytes in addition to the electron conduction path. The simplest ionic conduction path is to provide a liquid junction. To avoid mixing between the two electrolytes, the liquid junction can be provided through a porous plug that allows ion flow while reducing electrolyte mixing. To further minimize mixing of the electrolytes, a salt bridge can be used which consists of an electrolyte saturated gel in an inverted U-tube. A salt bridge, in Chemistry, is a laboratory device used to connect the Oxidation and reduction half-cells of a Galvanic cell (voltaic cell As the negatively charged electrons flow in one direction around this circuit, the positively charged metal ions flow in the opposite direction in the electrolyte.

A voltmeter is capable of measuring the change of electrical potential between the anode and the cathode. A galvanometer is a type of Ammeter; an instrument for detecting and measuring Electric current. At a point in space the electric potential is the Potential energy per unit of charge that is associated with a static (time-invariant Electric field

Electrochemical cell voltage is also referred to as electromotive force or emf. Electromotive force ( emf, \mathcal{E} is a term used to characterize electrical devices such as Voltaic cells thermoelectric devices electrical

A cell diagram can be used to trace the path of the electrons in the electrochemical cell. For example, here is a cell diagram of a Daniell cell:

First, the reduced form of the metal to be oxidized at the anode (Zn) is written. This is separated from its oxidized form by a vertical line, which represents the limit between the phases (oxidation changes). The double vertical lines represent the saline bridge on the cell. Finally, the oxidized form of the metal to be reduced at the cathode, is written, separated from its reduced form by the vertical line. The electrolyte concentration is given as it is an important variable in determining the cell potential.

Standard electrode potential

Main article: Standard electrode potential

To allow prediction of the cell potential, tabulations of standard electrode potential are available. In Electrochemistry, the standard electrode potential, abbreviated Eo E0 or EO (with a superscript Plimsoll character pronounced In Electrochemistry, the standard electrode potential, abbreviated Eo E0 or EO (with a superscript Plimsoll character pronounced Such tabulations are referenced to the standard hydrogen electrode (SHE). The standard hydrogen electrode undergoes the reaction

which is shown as reduction but, in fact, the SHE can act as either the anode or the cathode, depending on the relative oxidation/reduction potential of the other electrode/electrolyte combination. The standard hydrogen electrode (abbreviated SHE) also called normal hydrogen electrode ( NHE) is a Redox electrode which forms the basis of The term standard in SHE requires a supply of hydrogen gas bubbled through the electrolyte at a pressure of 1 atm and an acidic electrolyte with H+ activity equal to 1 (usually assumed to be [H+] = 1 mol/liter).

The SHE electrode can be connected to any other electrode by a salt bridge to form a cell. If the second electrode is also at standard conditions, then the measured cell potential is called the standard electrode potential for the electrode. The standard electrode potential for the SHE is zero, by definition. The polarity of the standard electrode potential provides information about the relative reduction potential of the electrode compared to the SHE. If the electrode has a positive potential with respect to the SHE, then that means it is a strongly reducing electrode which forces the SHE to be the anode (an example is Cu in aqueous CuSO4 with a standard electrode potential of 0. 337 V). Conversely, if the measured potential is negative, the electrode is more oxidizing than the SHE (such as Zn in ZnSO4 where the standard electrode potential is -0. 763 V).

Standard electrode potentials are usually tabulated as reduction potentials. However, the reactions are reversible and the role of a particular electrode in a cell depends on the relative oxidation/reduction potential of both electrodes. The oxidation potential for a particular electrode is just the negative of the reduction potential. A standard cell potential can be determined by looking up the standard electrode potentials for both electrodes (sometimes called half cell potentials). The one that is smaller will be the anode and will undergo oxidation. The cell potential is then calculated as the sum of the reduction potential for the cathode and the oxidation potential for the anode.

For example, the standard electrode potential for a copper electrode is:

At standard temperature, pressure and concentration conditions, the cell's emf (measured by a multimeter) is 0. Electromotive force ( emf, \mathcal{E} is a term used to characterize electrical devices such as Voltaic cells thermoelectric devices electrical A multimeter or a multitester, also known as a volt/ohm meter or VOM, is an electronic Measuring instrument that combines several 34 V. by definition, the electrode potential for the SHE is zero. Thus, the Cu is the cathode and the SHE is the anode giving

Or,

Changes in the stoichiometric coefficients of a balanced cell equation will not change value because the standard electrode potential is an intensive property. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry is the Calculation of Quantitative (measurable In the Physical sciences an intensive property (also called a bulk property) is a Physical property of a system that does not depend on the

Spontaneity of Redox reaction

Main article: Spontaneous process

During operation of electrochemical cells, chemical energy is transformed into electrical energy and is expressed mathematically as the product of the cell's emf and the electrical charge transferred through the external circuit. A spontaneous process is the time-evolution of a system in which it releases free energy (most often as heat and moves to a lower more thermodynamically stable energy state In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Electric energy is the potential energy associated with the conservative Coulomb forces between Charged particles contained within a system, where Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction.

where is the cell potential measured in volts (V) and is the cell current integrated over time and measured in coulumbs (C). can also be determined by multiplying the total number of electrons transferred (measured in moles) times Faraday's constant, F = 96,485 C/mole.

The emf of the cell at zero current is the maximum possible emf. It is used to calculate the maximum possible electrical energy that could be obtained from a chemical reaction. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called This energy is referred to as electrical work and is expressed by the following equation:

where work is defined as positive into the system. Electrical work is the work done on a charged particle by an Electric field.

Since the free energy is the maximum amount of work that can be extracted from a system, one can write:

A positive cell potential gives a negative change in Gibbs free energy. In Thermodynamics, the term thermodynamic free energy refers to the amount of work that can be extracted from a System, and is helpful in Engineering This is consistent with the cell production of an electric current flowing from the cathode to the anode through the external circuit. If the current is driven in the opposite direction by imposing an external potential, then work is done on the cell to drive electrolysis.

A spontaneous electrochemical reaction (change in Gibbs free energy less than zero) can be used to generate an electric current, in electrochemical cells. Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. An electrochemical cell is a device used for generating an Electromotive force ( Voltage) and current from chemical reactions. This is the basis of all batteries and fuel cells. A fuel cell is an electrochemical conversion device It produces electricity from Fuel (on the Anode side and an oxidant (on the For example, gaseous oxygen (O₂) and hydrogen (H₂) can be combined in a fuel cell to form water and energy, typically a combination of heat and electrical energy.

Conversely, non-spontaneous electrochemical reactions can be driven forward by the application of a current at sufficient voltage. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical The electrolysis of water into gaseous oxygen and hydrogen is a typical example. In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current

The relation between the equilibrium constant and the Gibbs free energy for an electrochemical cell is expressed as follows:

Rearranging to express the relation between standard potential and equilibrium constant yields

Previous equation can use Briggsian logarithm as shown below:

Cell emf dependency on changes in concentration

Nernst Equation

Main article: Nernst Equation

The standard potential of an electrochemical cell requires standard conditions for all of the reactants. For a general Chemical reaction \alpha A +\beta B. \rightleftharpoons \sigma S+\tau T. The common logarithm is the Logarithm with base 10 It is also known as the decadic logarithm, named after its base In Electrochemistry, the Nernst equation is an equation which can be used (in conjunction with other information to determine the equilibrium Reduction potential When reactant concentrations differ from standard conditions, the cell potential will deviate from the standard potential. In the 20th century German chemist Walther Hermann Nernst proposed a mathematical model to determine the effect of reactant concentration on electrochemical cell potential. A chemist is a Scientist trained in the Science of Chemistry. Walther Hermann Nernst ( June 25, 1864 &ndash November 18, 1941) was a German Physicist who is known for his theories

In the late 19th century Josiah Willard Gibbs had formulated a theory to predict whether a chemical reaction is spontaneous based on the free energy

,

Where:

ΔG = change in Gibbs free energy, T = absolute temperature, R = gas constant, ln = natural logarithm, Q = reaction quotient. Josiah Willard Gibbs ( February 11, 1839 &ndash April 28, 1903) was an American theoretical Physicist, Chemist In Thermodynamics, the Gibbs free energy ( IUPAC recommended name Gibbs energy or Gibbs function) is a Thermodynamic potential which Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Relationship with the Boltzmann constant The Boltzmann constant kB (often abbreviated k) may be used in place of the gas constant by working The natural logarithm, formerly known as the Hyperbolic logarithm is the Logarithm to the base e, where e is an irrational In Chemistry, reaction quotient is a quantitative measure of the extent of reaction the relative proportion of products and reactants present in the reaction mixture at some

Gibbs' key contribution was to formalize the understanding of the effect of reactant concentration on spontaneity.

Based on Gibbs' work, Nernst extended the theory to include the contribution from electric potential on charged species. As shown in the previous section, the change in Gibbs free energy for an electrochemical cell can be related to the cell potential. Thus, Gibbs' theory becomes

Where:

n = number of electrons/mole product, F = Faraday constant (coulombs/mole), and ΔE = cell potential. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The mole (symbol mol) is a unit of Amount of substance: it is an SI base unit, and almost the only unit to be used to measure this In Physics and Chemistry, the Faraday constant (named after Michael Faraday) is the magnitude of Electric charge per mole of The coulomb (symbol C) is the SI unit of Electric charge. It is named after Charles-Augustin de Coulomb. The mole (symbol mol) is a unit of Amount of substance: it is an SI base unit, and almost the only unit to be used to measure this The Membrane potential, or better Membrane Voltage, is the difference of Electric potentials between two Aqueous solutions separated by a (

Finally, Nernst divided through by the amount of charge transferred to arrive at a new equation which now bears his name:

Assuming standard conditions () and R = the equation above can be expressed on Base—10 logarithm as shown below:

Concentration cells

Main article: Concentration cell

A concentration cell is an electrochemical cell where the two electrodes are the same material, the electrolytes on the two half-cells involve the same ions, but the electrolyte concentration differs between the two half-cells. Relationship with the Boltzmann constant The Boltzmann constant kB (often abbreviated k) may be used in place of the gas constant by working The common logarithm is the Logarithm with base 10 It is also known as the decadic logarithm, named after its base A Concentration cell is an Electrochemical cell that has two equivalent half-cells of the same material differing only in concentrations

For example an electrochemical cell, where two copper electrodes are submerged in two copper(II) sulfate solutions, whose concentrations are 0. Copper(II sulfate is the Chemical compound with the formula Cu[[Sulfur S]] O 4 05 M and 2. In Chemistry, molar concentration, also called molarity, is a measure of the Concentration of a Solute in a Solution, or of any 0 M, connected through a salt bridge. In Chemistry, molar concentration, also called molarity, is a measure of the Concentration of a Solute in a Solution, or of any This type of cell will generate a potential that can be predicted by the Nernst equation. Both electrodes undergo the same chemistry (although the reaction proceeds in reverse at the cathode)

Le Chatelier's principle indicates that the reaction is more favourable to reduction as the concentration of ions increases. In Chemistry, Le Chatelier's Principle, also called the Le Chatelier-Braun principle, can be used to predict the effect of a change in conditions on a Chemical Reduction will take place in the cell's compartment where concentration is higher and oxidation will occur on the more dilute side.

The following cell diagram describes the cell mentioned above:

Where the half cell reactions for oxidation and reduction are:

Where the cell's emf is calculated through Nernst equation as follows:

's value of this kind of cell is zero, as electrodes and ions are the same in both half-cells. After replacing values from the case mentioned, it is possible to calculate cell's potential:

However, this value is only approximate, as reaction quotient is defined in terms of ion activities which can be approximated with the concentrations as calculated here.

The Nernst equation plays an important role in understanding electrical effects in cells and organelles. Such effects include nerve synapses and cardiac beat as well as the resting potential of a somatic cell. Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands Cardiac cycle is the term referring to all or any of the events related to the flow of blood that occur from the beginning of one heartbeat to the beginning of the next

Battery

Main article: Battery (electricity)

A battery is an electrochemical cell (sometimes several in series) used for chemical energy storage. In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy Batteries are optimized to produce a constant electric current for as long as possible. Although the cells discussed previously are useful for theoretical purposes and some laboratory experiments, the large internal resistance of the salt bridge make them inappropriate battery technologies. Various alternative battery technologies have been commercialized as discussed next.

Dry cell

Main article: Dry cell

Dry cells do not have a fluid electrolyte. FLUID ( F ast L ight '''U'''ser '''I'''nterface D esigner is a graphical editor that is used to produce FLTK Source code Instead, they use a moist electrolyte paste. Leclanché's cell is a good example of this, where the anode is a zinc container surrounded by a thin layer of manganese dioxide and a moist electrolyte paste of ammonium chloride and zinc chloride mixed with starch. A Zinc-carbon Dry cell or battery is packaged in a Zinc can that serves as both a container and anode Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Manganese(IV oxide is the Chemical compound MnO2 commonly called manganese dioxide. Ammonium chloride ( N[[Hydrogen H]]4 Cl) (also Sal Ammoniac, salmiac, nushadir salt, zalmiak, sal armagnac Zinc chloride is the name of Chemical compound with the formula Zn[[chlorine Cl]]2 and its hydrates Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide The cell's cathode is represented by a carbon bar inserted on the cell's electrolyte, usually placed in the middle.

Leclanché's simplified half reactions are shown below:

The voltage obtained from the zinc-carbon battery is around 1. Georges Leclanché ( 1839 - September 14, 1882) was a French electrical engineer chiefly remembered for his invention of the Leclanché cell, A Zinc-carbon Dry cell or battery is packaged in a Zinc can that serves as both a container and anode 5 V. The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force.

Mercury battery

Main article: Mercury battery

The mercury battery has many applications in medicine and electronics. Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical The battery consists of a steel—made container in the shape of a cylinder acting as the cathode, where an amalgamated anode of mercury and zinc is surrounded by a stronger alkaline electrolyte and a paste of zinc oxide and mercury(II) oxide. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Zinc oxide is a Chemical compound with the formula ZnO It is nearly insoluble in water but soluble in Acids and Bases It occurs Mercury(II oxide, also called mercuric oxide, has a formula of Hg[[oxygen O]] and a formula weight of 216

Mercury battery half reactions are shown below:

There are no changes in the electrolyte's composition when the cell works. Such batteries provide 1. 35 V of direct current. Direct current ( DC) is the unidirectional flow of Electric charge.

Lead-acid battery

Main article: Lead-acid battery

The lead-acid battery used in automobiles, consists of a series of six identical cells assembled in series. Lead-acid batteries, invented in 1859 by French Physicist Gaston Planté, are the oldest type of Rechargeable battery. Each cell has a lead anode and a cathode made from lead dioxide packed in a metal plaque. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Lead(IV oxide, PbO2 also plumbic oxide and lead dioxide, is an Oxide of Lead, with lead in Oxidation state +4 The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Cathode and anode are submerged in a solution of sulfuric acid acting as the electrolyte. Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid.

Lead-acid battery half cell reactions are shown below:

At standard conditions, each cell may produce a potential of 2 V, hence overall voltage produced is 12 V. The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. Differing from mercury and zinc-carbon batteries, lead-acid batteries are rechargeable. See also Rechargeable electricity storage system A rechargeable battery, also known as a storage battery, is a group of two or more secondary If an external voltage is supplied to the battery it will produce an electrolysis of the products in the overall reaction (discharge), thus recovering initial components which made the battery work. In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current

Lithium rechargeable battery

Main article: Lithium battery

Instead of an aqueous electrolyte or a moist electrolyte paste, a solid state battery operates using a solid electrolyte. Lithium batteries are not to be confused with lithium-ion batteries which are high energy-density rechargeable batteries Lithium batteries are Lithium polymer batteries are an example of this; a graphite bar acts as the anode, a bar of lithium cobaltate acts as the cathode, and a polymer, swollen with a lithium salt, allows the passage of ions and serves as the electrolyte. Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge In this cell, the carbon in the anode can reversibly form a lithium-carbon alloy. Upon discharging, lithium ions spontaneously leave the lithium cobaltate cathode and travel through the polymer and into the carbon anode forming the alloy. This flow of positive lithium ions is the electrical current that the battery provides. By charging the cell, the lithium dealloys and travels back into the cathode. The advantage of this kind of battery is that Lithium possess the highest negative value of standard reduction potential. It is also a light metal and therefore less mass is required to generate 1 mole of electrons. Light metals are Metals of low Atomic weight. The cut off between light metals and Heavy metals varies In Physics and Chemistry, the Faraday constant (named after Michael Faraday) is the magnitude of Electric charge per mole of Lithium ion battery technologies are widely used in portable electronic devices because they have high energy storage density and are rechargeable. These technologies show promise for future automotive applications, with new materials such as iron phosphates and lithium vanadates.

Flow battery/ Redox flow battery

Main article: Flow battery

Most batteries have all of the electrolyte and electrodes within a single housing. A flow battery is a form of Rechargeable battery in which Electrolyte containing one or more dissolved electroactive species flows through a power cell / reactor A flow battery is unusual in that the majority of the electrolyte, including dissolved reactive species, is stored in separate tanks. The electrolytes are pumped through a reactor, which houses the electrodes, when the battery is charged or discharged.

These types of batteries are typically used for large-scale energy storage (kWh - multi MWh). Of the several different types that have been developed, some are of current commercial interest, including the vanadium redox battery and zinc bromine battery. The vanadium redox (and redox flow battery in its present form (with sulfuric acid electrolytes was patented by the University of New South Wales in Australia in 1986. The zinc-bromine flow battery is a type of hybrid flow battery

Fuel cells

Main article: Fuel cell

Fossil fuels are used in power plants to supply electrical needs, however their conversion into electricity is an inefficient process. A fuel cell is an electrochemical conversion device It produces electricity from Fuel (on the Anode side and an oxidant (on the Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of The most efficient electrical power plant may only convert about 40% of the original chemical energy into electricity when burned or processed. In Mathematics, a percentage is a way of expressing a number as a Fraction of 100 ( per cent meaning "per hundred" In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of

To enhance electrical production, scientists have developed fuel cells where combustion is replaced by electrochemical methods, similar to a battery but requiring continuous replenishment of the reactants consumed. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of A reagent or reactant is a substance or compound consumed during a Chemical reaction.

The most popular is the oxygen-hydrogen fuel cell, where two inert electrodes (porous electrodes of nickel and nickel oxide) are placed in an electrolytic solution such as hot caustic potash, in both compartments (anode and cathode) gaseous hydrogen and oxygen are bubbled into solution. Porosity is a measure of the void spaces in a material and is measured as a fraction between 0–1 or as a Percentage between 0–100% Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Potassium hydroxide is the Inorganic compound with the formula K[[hydroxide OH]] Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the

Oxygen-hydrogen fuel cell reactions are shown bellow:

The overall reaction is identical to hydrogen combustion. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of Oxidation and reduction take place in the anode and cathode separately. A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device This is similar to the electrode used in the cell for measuring standard reduction potential which has a double function acting as electrical conductors providing a surface required to decomposition of the molecules into atoms before electron transferring, thus named electrocatalysts. In Science and engineering, a conductor is a material which contains movable Electric charges. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Platinum, nickel, and rhodium are good electrocatalysts. Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Rh redirects here For other uses see Rh (disambiguation Rhodium (ˈroʊdiəm is a Chemical element with the symbol

Corrosion

Main article: Corrosion

Corrosion is the term applied to metal rust caused by an electrochemical process. Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Rust is a general term for a series of Iron oxides, usually red oxides formed by the reaction of Iron with Oxygen in the presence of water or air Most people are likely familiar with the corrosion of iron, in the form of reddish rust. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Other examples include the black tarnish on silver, and red or green corrosion that may appear on copper and its alloys, such as brass. Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Brass is any Alloy of Copper and Zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties The cost of replacing metals lost to corrosion is in the multi-billions of dollars per year. The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been

Iron corrosion

For iron rust to occur the metal has to be in contact with oxygen and water, although chemical reactions for this process are relatively complex and not all of them are completely understood, it is believed the causes are the following:

1. Electron transferring (Reduction-Oxidation)
   1. One area on the surface of the metal acts as the anode, which is where the oxidation (corrosion) occurs. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Water is a common Chemical substance that is essential for the survival of all known forms of Life. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called At the anode, the metal gives up electrons.

      1. 

   2. Electrons are transferred from iron reducing oxygen in the atmosphere into water on the cathode, which is placed in another region of the metal. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as

      1. 

   3. Global reaction for the process:

      

   4. Standard emf for iron rusting:

      1. 

         

Iron corrosion takes place on acid medium; H⁺ ions come from reaction between carbon dioxide in the atmosphere and water, forming carbonic acid. In Chemistry, hydronium is the obsolete name for the Cation H 3 O + derived from Protonation of Water An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Carbonic acid (ancient name acid of air or aerial acid) has the formula H2CO3 Fe²⁺ ions oxides, following this equation:

Iron(III) oxide hydrated is known as rust. Iron(III oxide —also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply Rust —is Hydrate is a term used in Inorganic chemistry and Organic chemistry to indicate that a substance contains Water. Water associated with iron oxide it varies, thus chemical representation is presented as . The electric circuit works as passage of electrons and ions occurs, thus if an electrolyte is present it will facilitate oxidation, this explains why rusting is quicker on salt water. An electrical network is an interconnection of Electrical elements such as Resistors Inductors Capacitors Transmission lines Voltage Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Brine (lat saltus) is Water saturated or nearly saturated with Salt (NaCl

Corrosion of common metals

Coinage metals, such as copper and silver, slowly corrode through use. See also A patina of green-blue copper carbonate forms on the surface of copper with exposure to the water and carbon dioxide in the air. Patina is a coating of various chemical compounds such as Oxides or Carbonates formed on the surface of metal during exposure to Weathering. Copper(II carbonate (often called copper carbonate or cupric carbonate) is a blue-green compound (chemical formula CuCO3 forming part of the Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Silver coins or cutlery that are exposed to high sulfur foods such as eggs or the low levels of sulfur species in the air develop a layer of black Silver sulfide. Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Cutlery refers to any hand Implement used in preparing serving and especially eating Food in the Western world. An egg is a round or oval body laid by the female of many animals consisting of an Ovum surrounded by layers of Membranes and an outer casing which acts to nourish Silver sulfide (or Silver sulphide in British English Ag2S is the Sulfide of Silver.

Gold and platinum are extremely difficult to oxidize under normal circumstances, and require exposure to a powerful chemical oxidizing agent such as aqua regia. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Aqua regia ( Latin for royal water) is a highly corrosive fuming yellow or red solution

Some common metals oxidize extremely rapidly in air. Titanium and aluminium oxidize instantaneouly in contact with the oxygen in the air. Titanium (taɪˈteɪniəm is a Chemical element with the symbol Ti and Atomic number 22 These metals form an extremely thin layer of oxidized metal on the surface. This thin layer of oxide protects the underlying layers of the metal from the air preventing the entire metal from oxidizing. These metals are used in applications where corrosion resistance is important. Iron, in contrast, has an oxide that forms in air and water, called rust, that does not stop the further oxidation of the iron. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Rust is a general term for a series of Iron oxides, usually red oxides formed by the reaction of Iron with Oxygen in the presence of water or air Thus iron left exposed to air and water will continue to rust until all of the iron is oxidized.

Prevention of corrosion

Attempts to save a metal from becoming anodic are of two general types. Anodic regions dissolve and destroy the structural integrity of the metal.

While it is almost impossible to prevent anode/cathode formation, if a non-conducting material covers the metal, contact with the electrolyte is not possible and corrosion will not occur. A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device An insulator, also called a Dielectric, is a material that resists the flow of Electric current. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium

Coating

Metals are coated on its surface with paint or some other non-conducting coating. Paint is any Liquid, liquifiable or mastic composition which after application to a substrate in a thin layer is converted to an opaque Solid This prevents the electrolyte from reaching the metal surface if the coating is complete. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium Scratches exposing the metal will corrode with the region under the paint, adjacent to the scratch, to be anodic.

Other prevention is called passivation where a metal is coated with another metal such as a tin can. Passivation is the process of making a material "passive" in relation to another material prior to using the materials together A tin can, also called a tin (especially in British English) or a can, is an air-tight container for the distribution or storage of Tin is a metal that rapidly corrodes to form a mono-molecular oxide coating that prevents further corrosion of the tin. An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element The tin prevents the electrolyte from reaching the base metal, usually steel (iron). Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 However, if the tin coating is scratched the iron becomes anodic and the can corrodes rapidly.

Sacrificial anodes

A method commonly used to protect a structural metal is to attach a metal which is more anodic than the metal to be protected. This forces the structural metal to be cathodic, thus spared corrosion. A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device It is called "sacrificial" because the anode dissolves and has to be replaced periodically.

Zinc bars are attached at various locations on steel ship hulls to render the ship hull cathodic. Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 A ship /ʃɪp/ is a large vessel that floats on water Ships are generally distinguished from Boats based on size A hull is the body of a Ship or Boat. It is a central concept in floating vessels as it provides the Buoyancy that keeps the vessel from sinking A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device The zinc bars are replaced periodically. Other metals, such as magnesium, would work very well but zinc is the least expensive useful metal. Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24

To protect pipelines, an ingot of buried or exposed magnesium (or zinc) is buried beside the pipeline and is connected electrically to the pipe above ground. Bury is a town in Greater Manchester, England. It lies on the River Irwell, north-northwest of the city of Manchester, west-southwest of A pipe is a tube or hollow cylinder used to convey materials or as a structural component A wire is a single usually cylindrical, elongated string of drawn Metal. The pipeline is forced to be a cathode and is protected from being oxidized and rusting. The magnesium anode is sacrificed. At intervals new ingots are buried to replace those lost. An ingot is a material usually metal that is cast into a shape suitable for further processing

Electrolysis

Main article: Electrolysis

The spontaneous redox reactions of a conventional battery produce electricity through the different chemical potentials of the cathode and anode in the electrolyte. In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current However, electrolysis requires an external source of electrical energy to induce a chemical reaction, and this process takes place in a compartment called electrolytic cell. Electric energy is the potential energy associated with the conservative Coulomb forces between Charged particles contained within a system, where An electrolytic cell decomposes chemical compounds by means of electrical energy in a process called Electrolysis; the Greek word Lysis means to break up

Electrolysis of molten sodium chloride

When molten, the salt sodium chloride can be electrolyzed to yield metallic sodium and gaseous chlorine. For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Industrially this process takes place in a special cell named Down's cell. The cell is connected to an electrical power supply, allowing electrons to migrate from the power supply to the electrolytic cell. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J

Reactions that take place at Down's cell are the following:

This process can yield large amounts of metallic sodium and gaseous chlorine, and is widely used on mineral dressing and metallurgy industries. Ore dressing is one of the principal processes in the work of Mining. Metallurgy is a domain of Materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious"

The emf for this process is approximately -4 V indicating a (very) non-spontaneous process. V is the twenty-second letter in the modern Latin alphabet. Its name in English is spelled vee or occasionally ve (viː In order for this reaction to occur the power supply should provide at least a potential of 4 V. However, larger voltages must be used for this reaction to occur at a high rate.

Electrolysis of water

Main article: Electrolysis of water

Water can be converted to its component elemental gasses, H₂ and O₂ through the application of an external voltage. Electrolysis of water is the decomposition of Water (H2O into Oxygen (O2 and Hydrogen gas (H2 Water doesn't decompose into hydrogen and oxygen spontaneously as the Gibbs free energy for the process at standard conditions is about 474. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the A spontaneous process is the time-evolution of a system in which it releases free energy (most often as heat and moves to a lower more thermodynamically stable energy state In Thermodynamics, the Gibbs free energy ( IUPAC recommended name Gibbs energy or Gibbs function) is a Thermodynamic potential which 4 kJ. The decomposition of water into hydrogen and oxygen can be performed in an electrolytic cell. In it, a pair of inert electrodes usually made of platinum immersed in water act as anode and cathode in the electrolytic process. An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 The electrolysis starts with the application of an external voltage between the electrodes. This process will not occur except at extremely high voltages without an electrolyte such as sodium chloride or sulfuric acid (most used 0. For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. 1 M). In Chemistry, molar concentration, also called molarity, is a measure of the Concentration of a Solute in a Solution, or of any

Bubbles from the gases will be seen near both electrodes. The following half reactions describe the process mentioned above:

Although strong acids may be used in the apparatus, the reaction will not net consume the acid. While this reaction will work at any conductive electrode at a sufficiently large potential, platinum catalyzes both hydrogen and oxygen formation, allowing for relatively mild voltages (~2V depending on the pH). Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst pH is the measure of the acidity or alkalinity of a Solution.

Electrolysis of aqueous solutions

Electrolysis in an aqueous is a similar process as mentioned in electrolysis of water. However, it is considered to be a complex process because the contents in solution have to be analyzed in half reactions, whether reduced or oxidized. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called

Electrolysis of a solution of sodium chloride

The presence of water in a solution of sodium chloride must be examined in respect to its reduction and oxidation in both electrodes. For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Usually, water is electrolysed as mentioned in electrolysis of water yielding gaseous oxygen in the anode and gaseous hydrogen in the cathode. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 On the other hand, sodium chloride in water dissociates in Na⁺ and Cl^- ions, anion will be attracted to the cathode, thus reducing the sodium ion. Dissociation in Chemistry and Biochemistry is a general process in which ionic compounds ( complexes, Molecules, or Salts) separate An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 The cation will then be attracted to the anode oxidizing chloride ion. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge The chloride Ion is formed when the element Chlorine picks up one Electron to form an Anion (negatively-charged ion Cl&minus

The following half reactions describes the process mentioned:

Reaction 1 is discarded as it has the most negative value on standard reduction potential thus making it less thermodynamically favorable in the process. A negative number is a Number that is less than zero, such as −2

When comparing the reduction potentials in reactions 2 & 4, the reduction of chloride ion is favored. Thus, if the Cl^- ion is favored for reduction, then the water reaction is favored for oxidation producing gaseous oxygen, however experiments shown gaseous chlorine is produced and not oxygen. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state

Although the initial analysis is correct, there is another effect that can happen, known as the overvoltage effect. When the Voltage in a circuit or part of it is raised above its upper design limit this is known as overvoltage. Additional voltage is sometimes required, beyond the voltage predicted by the . This may be due to kinetic rather than thermodynamic considerations. Chemical kinetics, also known as reaction kinetics is the study of rates of chemical processes In Thermodynamics and Physical chemistry, thermochemistry is the study of the Heat evolved or absorbed in Chemical reactions Thermochemistry In fact, it has been proven that the activation energy for the chloride ion is very low, hence favorable in kinetic terms. In Chemistry, activation energy, also called midnight energy, is a term introduced in 1889 by the Swedish scientist Svante Arrhenius, that is defined Chemical kinetics, also known as reaction kinetics is the study of rates of chemical processes In other words, although the voltage applied is thermodynamically sufficient to drive electrolysis, the rate is so slow that to make the process proceed in a reasonable time frame, the voltage of the external source has to be increased (hence, overvoltage). Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical

Finally, reaction 3 is favorable because it describes the proliferation of OH^- ions thus letting a probable reduction of H⁺ ions less favorable an option. In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen In Chemistry, hydronium is the obsolete name for the Cation H 3 O + derived from Protonation of Water

The overall reaction for the process according to the analysis would be the following:

As the overall reaction indicates, the concentration of chloride ions is reduced in comparison to OH^- ions (whose concentration increases). In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance The reaction also shows the production of gaseous hydrogen, chlorine and aqueous sodium hydroxide. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Sodium hydroxide ( Na[[hydroxide OH]]) also known as Lye, caustic soda and (incorrectly according to IUPAC nomenclature

Quantitative electrolysis & Faraday's Laws

Main article: Faraday's law of electrolysis

Quantitative aspects of electrolysis were originally developed by Michael Faraday in 1834. Faraday's laws of electrolysis are quantitative relationships based on the electrochemical researches published by Michael Faraday in 1834 Michael Faraday, FRS ( September 22 1791 – August 25 1867) was an English Faraday is also credited to have coined the terms electrolyte, electrolysis, among many others while he studied quantitative analysis of electrochemical reactions. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium Also he was an advocate of the law of conservation of energy. In Physics, the law of conservation of energy states that the total amount of Energy in an isolated system remains constant and cannot be created although it may

First law

Faraday concluded after several experiments on electrical current in non-spontaneous process, the mass of the products yielded on the electrodes was proportional to the value of current supplied to the cell, the length of time the current existed, and the molar mass of the substance analyzed. Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. A spontaneous process is the time-evolution of a system in which it releases free energy (most often as heat and moves to a lower more thermodynamically stable energy state Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object

In other words, the amount of a substance deposited on each electrode of an electrolytic cell is directly proportional to the quantity of electricity passed through the cell. In Physics the term quantity of Electricity refers to the quantity of Electric charge.

Below a simplified equation of Faraday's first law:

Where,

m is the mass of the substance produced at the electrode (in grams),

Q is the total electric charge that passed through the solution (in coulombs),

n is the valence number of the substance as an ion in solution (electrons per ion),

M is the molar mass of the substance (in grams per mole). For other uses of the words gram or gramme see Gram (disambiguation. The coulomb (symbol C) is the SI unit of Electric charge. It is named after Charles-Augustin de Coulomb. The mole (symbol mol) is a unit of Amount of substance: it is an SI base unit, and almost the only unit to be used to measure this

Second law

Main article: Electroplating

Faraday devised the laws of chemical electrodeposition of metals from solutions in 1857. Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object He formulated the second law of electrolysis stating "the amounts of bodies which are equivalent to each other in their ordinary chemical action have equal quantities of electricity naturally associated with them. " In other terms, the quantities of different elements deposited by a given amount of electricity are in the ratio of their chemical equivalent weights. A ratio is an expression which compares quantities relative to each other Equivalent weight is the amount of an element that reacts or is involved in reaction with 1 mole of electrons

An important aspect of the second law of electrolysis is electroplating which together with the first law of electrolysis, has a significant number of applications in the industry, as when used to protect metals to avoid corrosion. Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings

Applications

There are various extremely important electrochemical processes in both nature and industry, like the coating of objects with metals or metal oxides through electrodeposition and the detection of alcohol in drunken drivers through the redox reaction of ethanol. The generation of chemical energy through photosynthesis is inherently an electrochemical process, as is production of metals like aluminum and titanium from their ores. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Certain diabetes blood sugar meters measure the amount of glucose in the blood through its redox potential.

The nervous impulses in neurons are based on electric current generated by the movement of sodium and potassium ions into and out of cells, and certain animals like eels can generate a powerful voltage from certain cells that can disable much larger animals.

See also

References

• Electrochemistry. In Electrochemistry, the electrochemical potential, \bar{\mu} sometimes confusingly abbreviated to ECP is a Thermodynamic measure that combines the A Frost diagram is an Oxidation State Free Energy Diagram (OS Some criteria for editing this page have been debated and are displayed In Chemistry, a Pourbaix diagram, also known as a potential/pH diagram, maps out possible stable ( equilibrium) phases of an aqueous electrochemical system Redox titration (also called oxidation-reduction titration) is a type of Titration based on a Redox reaction between the Analyte and Titrant The Standard electrode potentials are Electrode potentials of Half cells at equilibrium Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object General Chemistry II by Dr. Michael Blaber. Retrieved on January 30, 2006.
• Electrochemistry. Corrosion. Retrieved on January 28, 2006.
• Michael Faraday. Biography. Retrieved on January 30, 2006.
• The Faraday law of electrochemistry. Faraday laws of electrochemistry. Retrieved on January 30, 2006.
• Chang, Raymond (2002). Raymond Chang is an Emeritus professor at Williams College in the Department of Chemistry. "Electrochemistry", Chemistry, 7th Edition, Mc Graw Hill. ISBN 0-07-365601-1.  
• L. Brown, Theodore; H. Eugene LeMay, Jr. , Bruce E. Bursten, Julia R. Burdge (2003). "Electrochemistry", Chemistry, 9th Edition, US: Pearson Education. ISBN 0-13-066997-0.  
• William Hill, John; Ralph H. Petrucci, Terry McCreary, Scott S. Perry (March 2004). "Electrochemistry", General Chemistry: An Integrated Approach, 7th Edition, Pearson Education, 1200. ISBN 0-13-140283-8.  
• McMurry, John; Robert C. Fay (March 2004). "Electrochemistry", Chemistry, 3rd Edition, Prentice Hall. ISBN 0-13-056765-5.  
• Laidler, Keith; John H. Meiser, Bryan C. Sanctuary (May 2002). "Electrochemistry", in Keith Laidler: Physical Chemistry, 4th Edition, Boston, U.S.: Houghton Mifflin Company College Division. The United States of America —commonly referred to as the ISBN 061815292X.  

External links

• Electrochemistry net
• The Electrochemical Society
• International Society of Electrochemistry (ISE)
• Electrochemistry Encyclopedia at Case Western Reserve University
• Electrochemistry Dictionary at Case Western Reserve University (size ~ 388KB)
• Experiments in Electrochemistry at Fun Science

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