A demonstration electrochemical cell setup resembling the Daniell cell. The two half-cells are linked by a salt bridge carrying ions between them. Electrons flow in the external circuit.

An electrochemical cell is a device used for creating an electromotive force (voltage) and current from chemical reactions. The current is caused by the reactions releasing and accepting electrons at the different ends of a conductor. A common example of an electrochemical cell is a standard 1.5-volt battery. Image File history File links ElectrochemCell. ... Image File history File links ElectrochemCell. ... Early 20th-century engraving of a gravity cell. ... The factual accuracy of this article is disputed. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... English chemists John Daniell (left) and Michael Faraday (right), both credited to be founders of electrochemistry as known today. ... e- redirects here. ... For other uses, see battery (disambiguation). ...

Overview

In each half-cell is a chemical undergoing either oxidation or reduction. In a full electrochemical cell, one side must be losing electrons (oxidation) to its electrode while the other half-cell gains electrons (reduction). If the atoms/ions involved in the reaction are metal, the same metal is used for each electrode. If the atoms/ions involved in the reaction at each half-cell are not metal, obviously no electrode can be constructed out of it. Nonreactive metals such as platinum are used as a substitute (as in the standard hydrogen electrode). Finally, a salt bridge is necessary to provide electrical contact between the cells—but without the solutions mixing. This can simply be a strip of filter paper soaked in saturated potassium nitrate (V) solution. Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily loses electrons to form positive ions (cations) and has metallic bonds between metal atoms. ... “Atomic” redirects here. ... “Multivalent” redirects here. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Atomic mass 195. ... A standard hydrogen electrode (abbreviated SHE) is a redox electrode which is placed in the basis of the thermodynamic scale of oxidation-reduction potentials. ... A salt bridge, in chemistry, is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell (electrochemical cell). ... Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid flow and is used to separate fine solids from liquids. ...

The Bunsen cell, invented by Robert Bunsen.

Different choices of substances for each half-cell results in varying potential differences. Each reaction is undergoing an equilibrium reaction between different oxidation states of the ions—when equilibrium is reached the cell cannot provide further voltage. In the half-cell which is undergoing oxidation, the closer the equilibrium lies to the ion/atom with the more positive oxidation state the more potential this reaction will provide. Similarly, in the reduction reaction, the further the equilibrium lies to the ion/atom with the more negative oxidation state the higher the potential. Image File history File linksMetadata Download high resolution version (582x649, 118 KB) Summary The Electro-Plating and Electro-Refining of Metals written by Arnold Philip Copyright 1911 Licensing This image is in the public domain in the United States. ... Image File history File linksMetadata Download high resolution version (582x649, 118 KB) Summary The Electro-Plating and Electro-Refining of Metals written by Arnold Philip Copyright 1911 Licensing This image is in the public domain in the United States. ... Bunsens cell The Bunsen cell, is a zinc-carbon electric cell (colloquially called battery) composed of a zinc electrode in dilute sulphuric acid separated by a porous diaphragm from a carbon (graphite) electrode in nitric or chromic acid. ... Robert Wilhelm Bunsen (born 31 March 1811 in Göttingen, died 16 August 1899 in Heidelberg) was a German chemist. ... Chemical equilibrium is the state in which the concentrations of the reactants and products have no net change over time. ...

This potential can be predicted quantitatively through the use of electrode potentials (the voltage measured when the substance is connected to hydrogen). The difference in voltage between electrode potentials gives a prediction for the potential measured. Spontaneity of a chemical reaction is determined by the overall cell potential Eo. If Eo>0, the reaction is spontaneous and if Eo<0, the reaction will not be spontaneous. This article may be too technical for most readers to understand. ... This article is about the chemistry of hydrogen. ...

The potential window is the electrochemical voltage range between which a substance does not get oxidized or reduced.

Cell types

• Concentration cell
• Electrolytic cell
• Galvanic cell
• Accumulator

A Concentration Cell is an electrochemical cell that has two equivalent half-cells of of the same material differing only in concentrations. ... Electrolytic cells are composed of an electrolyte (usually water or another solvent capable of dissolving various ions of interest), a cathode and an anode. ... The Galvanic cell, named after Luigi Galvani, consists of two metals connected by an electrolyte which forms a salt bridge between the metals. ... A secondary cell is any kind of electrolytic cell in which the electrochemical reaction that releases energy is reversible. ...

See also

energy Portal

• Electrochemical potential
• Nickel Cadmium battery
• Alkaline battery