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Topic: Electrochemical potential

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  Electrochemical potential - Wikipedia, the free encyclopedia
Electrochemical potential is a thermodynamic measure that combines the concepts of energy stored in the form of chemical potential and electrostatics.
The electrochemical potential difference between the two sides of the membrane in mitochondria, chloroplasts, bacteria and other membranous compartments that engage in active transport involving proton pumps, is at times called a chemiosmotic potential (see chemiosmotic hypothesis).
Electrochemical potential is measured in the laboratory and field using reference electrodes.
en.wikipedia.org /wiki/Electrochemical_potential   (463 words)

 Electrode potential - Wikipedia, the free encyclopedia
In electrochemistry, electrode potential (also called reversible potential difference or reversible potential difference of an electrode, and abbreviated E) is the potential difference of a half-reaction which occurs across a reversible cell made up of any electrode and a standard hydrogen electrode.
The potential of the cell as a whole is simply the combination of the two electrode potentials relative to a standard hydrogen electrode.
In this case a positive potential indicates that the equilibrium of the Fe /Fe reaction lies towards Fe, meaning that it accepts electrons from the hydrogen half-reaction.
en.wikipedia.org /wiki/Electrode_potential   (409 words)

 World Intellectual Property Organization   (Site not responding. Last check: 2007-11-07)
In one embodiment of the invention, an electrochemical reaction in the electrochemical cell is driven by a difference in electrochemical potential between the electrodes.
An electrochemical cell arranged for carrying out the method of any one of claims 1 to 17 including at least two electrodes and a plasma-producing means, wherein in use the electrodes contact a plasma produced by the plasma-producing means and the plasma acts as an electrolyte for the electrochemical cell.
An electrochemical cell according to claim 18 or claim 19 wherein a first electrode has a first electrochemical potential and a second electrode has a second electrochemical potential which may be equal to or not equal to the first electrochemical potential.
www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/89024.011122&ELEMENT_SET=DECL   (4479 words)

 World Intellectual Property Organization   (Site not responding. Last check: 2007-11-07)
Electrochemical noise measurements typically record the electrochemical current noise (ECN), that is the fluctuation in the current between two nominally identical electrodes, and the electrochemical potential noise (EPN), that is the fluctuation in potential of the current-measuring pair of electrodes with respect to a reference electrode.
Given that the applied potential fluctuation is also known, the impedance of the working electrode at the or each applied frequency can be calculated from the known potential fluctuation and the known current fluctuation at the or each frequency by dividing the voltage fluctuation by the current fluctuation.
signal which represents the electrochemical current noise, a measure of the impedance of the working electrode is derived from the applied current signal and the response signal, and a signal representing electrochemical potential noise is derived from the filtered signal and the derived impedance measure.
www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=03/106976.031224&ELEMENT_SET=DECL   (2333 words)

 Glosssary of Corrosion Related Terms
The partial derivative of the total electrochemical free energy of a constituent with respect to the number of moles of this constituent where all factors are kept constant.
This potential, sometimes called zeta potential, is a potential difference in the solution caused by residual, unbalanced charge distribution in the adjoining solution, producing a double layer.
The electrokinetic potential is different from the electrode potential in that it occurs exclusively in the solution phase; that is, it represents the reversible work necessary to bring a unit charge from infinity in the solution up to the interface in question but not through the interface.
www.corrosionsource.com /handbook/glossary/e_glos.htm   (1525 words)

 United States Patent Application: 0020070125   (Site not responding. Last check: 2007-11-07)
The method according to claim 1, wherein the applied electrochemical potential is greater than the anodization potential of the etch layer and smaller than the anodization potential of the epitaxial film.
The method according to claim 18, wherein the electrochemical potential is selected to be greater than the anodization potential of the etch layer and smaller than the anodization potential of the epitaxial layer structure.
Advantageously, the applied electrochemical potential is greater than the anodization potential of the etch layer and smaller than the anodization potential of the epitaxial film.
appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/PTO/search-adv.html&r=1&f=G&l=50&d=PG01&p=1&S1=20020070125.PGNR.&OS=DN/20020070125&RS=DN/20020070125   (5323 words)

 electrochemical noise   (Site not responding. Last check: 2007-11-07)
Electrochemical noise refers to naturally occurring fluctuations in corrosion potential and corrosion current flow.
Fluctuations in the corrosion potential can indicate a change in the thermodynamic state of corrosion processes, as for example indicated on a Pourbaix diagram*, while changes in the current noise is an indicator of the corrosion kinetics.
Electrochemical noise data can provide an indication of the type of corrosion damage that is occurring; it is widely used to distinguish between general and localized attack.
www.corrosion-club.com /noise.htm   (312 words)

The half-cell potential of this electrode serves as the reference point along the potential axis by which we judge the oxidizing or reducing power of the working electrode in the vicinity of the interfacial region between the working electrode and the electrolytic solution.
Since the half-cell potential of the reference electrode is taken as the arbitrary zero point along the electrochemical potential axis, it should not be surprising that oxidations may take place at negative potentials and reductions may take place at positive potentials.
For example, the detector potential at one electrode may be set sufficiently positive to oxidize all compounds of interest and the second electrode may be set at a substantially lower oxidizing potential to only react with those compounds that are electrochemically active at these lower potentials.
www.epsilon-web.net /Lc/manuals/Principles/Basic/basic.html   (6451 words)

 Electrochemistry   (Site not responding. Last check: 2007-11-07)
The potential of a voltaic cell depends on the concentrations of any species present in solution, the partial pressures of any gases involved in the reaction, and the temperature at which the reaction is run.
The overall potential for this cell is the sum of the potentials for the two half-cells.
This is important, because the half-cell potential for the reduction of this complex is considerably smaller than the potential for the reduction of the Ag ion.
chemed.chem.purdue.edu /genchem/topicreview/bp/ch20/electroframe.html   (3542 words)

 Controlling Marine Corrosion   (Site not responding. Last check: 2007-11-07)
This potential may be noted by the diver at the time the inspection is carried out or can be transmitted to the surface by the use of a Surface Display Unit.
The electrochemical potential of the structure under investigation at this location can be determined to a high degree of accuracy.
If the potential is in excess of 1,100mV versus a silver/silver chloride electrode, then excess levels of cathodic protection are being applied and there is a danger of cathodic disbondment, detachment of the structure coating.
www.underwater.com /archives/arch/026.03.shtml   (2953 words)

 Lecture 9, Electrochemical potential
To describe this, we need a new term, the electrochemical potential of our charged species, defined as the sum of the chemical and electrical potentials for the component (see definitions of work terms in lecture 3).
Transport of protons is of particular importance in biological energy conversion, because the proton circuit couples the free energy changes of electron transfer reactions to the phosphorylation of ADP to ATP, through the proton gradient.
p is the electrochemical proton gradient, often called the proton motive force (p.m.f.), measured in volts.
www.life.uiuc.edu /crofts/bioph354/lect9.html   (803 words)

Electrochemical corrosion monitoring is based on the assumption that corrosion is basically an electrochemical process that can be monitored through the measurement of potential and current that characterizes the corrosion process.
As described earlier, corrosion is an electrochemical process in which electrons are transferred between the anodic and cathodic area on the corroding metal resulting in oxidation (corrosion) of the metal at the anode and reduction of cations in the fluid at the cathode.
This arrangement minimizes the potential difference between the electrodes, enabling the voltmeter to operate on its optimal sensitivity range as the overall accuracy of measurement is limited by the resolution of the voltmeter.
www.geocities.com /ronak_vakil/corrosion_monitoring_techniques.html   (5786 words)

 Chemistry : Chapter 17 : Overview   (Site not responding. Last check: 2007-11-07)
Another characteristic of an electrochemical cell is that the oxidation and reduction half–reactions occur at surfaces called electrodes.
So that electrode potentials could be tabulated, one half–cell was defined as having an electrode potential of exactly 0 V. This half–cell is called the standard hydrogen electrode (SHE).
The standard cell potential is the difference between the reduction potential of the cathode and the reduction potential of the anode.
www.wwnorton.com /chemistry/overview/ch17.htm   (986 words)

 Summary of Electrochemical Theory   (Site not responding. Last check: 2007-11-07)
An electrochemical reaction is a reaction involving the transfer of charge as a part of a chemical reaction.
A half cell is an electrochemical reaction that results in a net surplus or deficit of electrons, and it corresponds to the smallest complete reaction sequence (while it may proceed as a sequence of simpler reactions, the intermediate stages are not stable).
Electrochemical measurements may be used to help to determine the reaction mechanism and the rate-controlling step.
www.umist.ac.uk /corrosion/lecturenotes/Echem/Electricityfile.html   (1050 words)

 Electrochemical potential   (Site not responding. Last check: 2007-11-07)
Electrochemical potential is a thermodynamic measure that reflects energy from entropy and electric charge and is typically invoked in molecule processes that involve diffusion.
It represents one of many interchangeable forms of potential energy through which energy may be conservation of energy.
The electrochemical potential difference between the two sides of the membrane in mitochondria, chloroplasts, bacterium and other membranous compartments that engage in active transport involving proton pumps, is at times called a chemiosmotic potential (see chemiosmotic hypothesis).
read-and-go.hopto.org /Thermodynamics/Electrochemical-potential.html   (424 words)

 Argentum Solutions Inc. - Sterling Guidance on Corrosion and Materials Degradation   (Site not responding. Last check: 2007-11-07)
corrosion potential — the potential of a corroding surface in an electrolyte relative to a reference electrode measured under open-circuit conditions.
electrochemical impedance — the frequency dependent, complex valued proportionality factor that relates the applied potential and the current response in an electrochemical cell.
Under some circumstances the quotient of the electrochemical potential noise divided by the electrochemical current noise is inversely proportional to the corrosion rate.
www.argentumsolutions.com /definitions.html   (1787 words)

 electrochemical corrosion monitoring   (Site not responding. Last check: 2007-11-07)
Electrochemical techniques rely on electrochemical corrosion theory and the measurement of electrochemical potentials and/or currents to monitor corrosion damage.
The electrochemical potential is fundamentally related to thermodynamics of corrosion reactions, while currents are related to reaction kinetics (rate of corrosion).
The relationship between electrochemical potential and current is important in several electrochemical corrosion monitoring techniques.
www.corrosion-club.com /elchem.htm   (205 words)

 Session GG2.1   (Site not responding. Last check: 2007-11-07)
For this purpose, a gradient of the electrochemical potential is set up inside a porous material, which serves as an active electrode in an electrolytic cell.
This potential gradient leads to a position dependent rate of electrochemical dissolution or deposition of the preform material and thus to a graded porosity.
The potential of the method will be demonstrated on the example of W/Cu-FGM's which are prepared by producing a graded tungsten preform by anodic dissolution and subsequent infiltration with copper.
www.mrs.org /meetings/fall97/abstract_book/GG/node9.html   (293 words)

The concepts of potential and field, as those of energy and force are general and applicable to any system in which potential energy is stored, be it electrical, hydraulic, gravitational or chemical.
It is then shown that the chemical potential, or free energy per mole, is the potential whose corresponding field may be considered to generate a force responsible for the directed movement of the particles.
The electrical potential difference established across the membrane is the potassium equilibrium potential which depends on the ratio of the concentrations of the ion on both sides of the membrane.
www.fiu.edu /~cuervol/PhysiologicalMechanisms/MembranePotential.htm   (3143 words)

 Getting Started with Electrochemical Corrosion Measurement   (Site not responding. Last check: 2007-11-07)
The potential of the metal is the means by which the anodic and cathodic reactions are kept in balance.
In electrochemical studies, a metal sample with a surface area of a few square centimeters is used to model the metal in a corroding system.
In electrochemical corrosion measurement, the equilibrium potential assumed by the metal in the absence of electrical connections to the metal is called the Open Circuit Potential, Eoc.
www.mtec.or.th /th/research/famd/corro/electrochem.html   (3560 words)

 [No title]
The energy available from the electrical potential difference across the membrane, plus from the proton gradient across the membrane, can be harnessed for secondary active transport, or cotransport.
Even K+ transport, which sometimes appears to be passive (down its electrochemical potential gradient) depends on the proton pump (and hence active transport) because it requires the electrogenic component of the membrane potential to balance the K+ concentrations gradient.
R is the gas constant; T is the absolute temperature; a is the valency of the ion for which the equilibrium concentration is calculated; F is Faraday's number.
soils.umn.edu /academics/classes/soil5611/content/Nutrient_Uptake   (1033 words)

 Characteristic Noise Frequencies in the Pitting Corrosion of 90Cu-10Ni Alloy   (Site not responding. Last check: 2007-11-07)
The present communication describes a study of the electrochemical behaviour of 90Cu-10Ni alloy in chloride solution, with particular attention to the electrochemical potential and current noise response, which provide information on the dynamics of the corrosion attack.
Based on the nature of this phenomena electrochemical techniques of study were applied: anodic polarization with reverse sweep, electrochemical potential and current noise and impedance spectroscopy.
The current and potential fluctuations were recorded over a period of time for a fixed potential or current, whichever is the case.
ce.eng.usf.edu /research_labs/corrosion/pg21.html   (490 words)

 Gamry Instruments, Inc. (Tech Tip) Potentiostat primer
The controlled variable in a potentiostat is the cell potential and the measured variable is the cell current.
The Working Electrode is the electrode where the potential is controlled and where the current is measured.
A ZRA is often used to measure galvanic corrosion phenomena and/or electrochemical noise.
www.gamry.com /App_Notes/Potentiostat_Primer.htm   (1156 words)

 ECC 1989 Introduction to Electro Conformational Coupling Page 3 of 18 - JWLABS
Electrochemical potential of ions have been postulated to play a major role in free energy transductions and information transfer of cells.
In photosynthetic processes, the energy of a photon is used to pump a proton into an energy reservoir and ATP synthase then uses the electrochemical potential energy of the proton for synthesis of ATP [7,9,10].
The electric potential across cell membranes is of the order of 10 to 250 mV, which corresponds to a field intensity of 20 to 500 kV/cm.
www.jwlabs.com /ecc3.htm   (427 words)

 Media Portfolio
By convention, electrochemical cells are written in the form: Anode-Salt bridge-Cathode, with the detail shown here.
The inert platinum strip acquires a potential that is determined by the equilibrium: 2 H+(aÊ=Ê1)Ê+Ê2 e-
However, as signified by the direction of electron flow and the negative voltage, the standard hydrogen electrode is the cathode.
cwx.prenhall.com /bookbind/pubbooks/hillchem3/medialib/media_portfolio/18.html   (952 words)

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