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Topic: Electrode potential

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  Standard Electrode Potentials
This potential is a measure of the energy per unit charge which is available from the oxidation/reduction reactions to drive the reaction.
The electrode potential depends upon the concentrations of the substances, the temperature, and the pressure in the case of a gas electrode.
The standard electrode potentials are customarily determined at solute concentrations of 1 Molar, gas pressures of 1 atmosphere, and a standard temperature which is usually 25°C. The standard cell potential is denoted by a degree sign as a superscript.
hyperphysics.phy-astr.gsu.edu /hbase/chemical/electrode.html   (1055 words)

 Silver Colloids: Definition of Terms
We cannot measure the "absolute" potential of an electrode; therefore, the electrode potential must always be referred to an "arbitrary zero point," defined by the potential of the reference electrode.
In equilibrium, the potential of the electrodes is the equilibrium potential and the cell voltage is the electromotive
It is important to note that the magnitude of the zeta potential is affected by both the nature of the surface of the particle, and the composition of the dispersant.
www.silver-colloids.com /Papers/definitions.html   (0 words)

 Electrochemistry Dictionary
An electrode that is shared by two series-coupled electrochemical cells in such a way that one side of the (usually planar) electrode acts as an anode in one cell and the other side acts as a cathode in the other cell.
An electrode reaction is considered to be under “diffusion control” when the overall rate of the reaction is is controlled by the rate of the diffusion of the reactants to the electrode surface rather than the rate of the reaction itself.
The concept of the Donnan potential is analogous to that of the equilibrium electrode potential.
electrochem.cwru.edu /ed/dict.htm   (11070 words)

 Electrochemistry P
This type of electrode is especially useful for removing small traces of impurities from the solution by electrolysis (e.g., waste treatment) because the solution is well stirred and it contacts a large surface of the electrode material.
The two current densities at which the electrode reaction is proceeding in the anodic and cathodic directions at an electrode potential.
It is related to the irreversible phenomena at the electrodes (electrode polarization) or in the electrolytic phase (concentration polarization).
www.corrosion-doctors.org /Dictionary/Dictionary-P.htm   (1837 words)

 OMEGA ENGINEERING - Electrode Basics
The potential generated at the junction site of the measuring portion is due to the free hydrogen ions present in solution.
The potential of the reference portion is produced by the internal element in contact with the reference fill solution.
Electrode demise can usually be characterized by a sluggish response, erratic readings or a reading which will not change.
www.omega.com /techref/ph-3.html   (832 words)

 BASi LC News
The role of the reference electrode in any electrochemical cell is to provide a stable half-cell potential; that is, it serves as the reference point along the potential axis which represents the oxidizing or reducing power of the working electrode.
These electrode potentials are determined by variables such as the half-cell reaction, the concentrations or the activities of the components of the half-cell, temperature, etc. X is a molecule (caffeic acid) which is oxidized at approximately +500 mV relative to the Ag/AgCl electrode.
Since the reference electrode potential is set as the zero point on the potential axis, it should not be surprising that oxidations may take place at negative potentials, and reductions at positive potentials.
www.bioanalytical.com /info/newsletter/LC/0412   (1696 words)

 Silver chloride electrode   (Site not responding. Last check: )
The electrode is a silver wire that is coated with a thin layer of silver chloride either by electroplating or by dipping the wire in molten silver chloride.
The potential of the electrode remains constant as long as the chloride concentration remains constant.
The silver-silver chloride reference electrode develops a potential proportional to the chloride concentration, whether it is sodium chloride, potassium chloride, ammonium chloride or some other chloride salt.
www.corrosion-doctors.org /References/silver.htm   (406 words)

 Battery and Cell Chemistries. Battery primer.
The cathode or positive electrode (the oxidising electrode) which accepts electrons from the external circuit and is reduced during the electrochemical (discharge) reaction.
The model of the cell as two half cells is used by electro-chemists and cell designers to calculate electrode potentials and and characterise the chemical reactions within the cell.
The larger the difference between the electrode potentials of the anode and cathode, the greater the EMF of the cell and the greater the amount of energy that can be produced by the cell.
www.axeonpower.com /chemistries.htm   (0 words)

 Galvanic Cells and Electrode Potential
If oxidation-reduction reactions are split into half-reactions, it is possible to arbitrarily assign to each a voltage (the reduction potential) that indicates the relative tendency of that half-reaction to occur.
The anode is to be connected to the negative wire (fl) from the voltmeter.
Record the voltage and which electrode is the anode.
www.sonoma.edu /users/b/brooks/115b/galvanic.html   (774 words)

 E - Glossary of chemical terms
Electrode potential is defined as the potential of a cell consisting of the electrode in question acting as a cathode and the standard hydrogen electrode acting as an anode.
Electrode potential is defined by measuring the potential relative to a standard hydrogen half cell
Potential energy is the energy stored in a body or system as a consequence of its position, shape, or state (this includes gravitational energy, electrical energy, nuclear energy, and chemical energy).
www.ktf-split.hr /periodni/en/abc/e.html   (0 words)

 Electrode potential
This potential difference can be measured by comparison with a reference electrode where the potential difference between the two phases is known.
The ultimate reference is the normal hydrogen electrode, the potential of which is defined as zero.
An equilibrium is established between the ions and adsorbed gas and the metal which determines the potential of the electrode.
www.tannerm.com /electrodePotential.htm   (0 words)

 Chemistry : Chapter 17 : Overview   (Site not responding. Last check: )
Since cells separate the half–reactions, it is often convenient to talk about the potential of the half–reaction or the electrode potential.
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)

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.
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.
In this mode, the working electrodes are poised in a potential region where the response of the analyte of interest is dramatically different; that is, where the slope of the current-potential curve is large.
www.epsilon-web.net /Lc/manuals/Principles/Basic/basic.html   (6453 words)

 Electrochemistry Encyclopedia --- Polarography)
Simple principle of polarography is the study of solutions or of electrode processes by means of electrolysis with two electrodes, one polarizable and one unpolarizable, the former formed by mercury regularly dropping from a capillary tube.
The dropping mercury electrode was polarized by alternating current and the corresponding rapid changes of electrode potential were followed on the screen of an oscilloscope.
For analytical purposes the potential dependence of the first derivative of electrode potential by time was used – it formed a closed, oval-shaped curve, with cathodic and anodic branches opposite each other; on such a curve, the electrolytic processes appeared as indentations.
electrochem.cwru.edu /ed/encycl/art-p03-polarography.htm   (5298 words)

 Experimental Unit A
The potential of the standard reference electrode is constant and ideally does not change during the measurement.
The p function is directly proportional to the measured potential and by definition is equal to the negative log of the activity of the analyte, i.e.
Electrode manufacturers recommend that a new or cleaned electrode be soaked in water, or buffer followed by water, for up to several days to establish the gel layer.
www.msu.edu /~bchug/bch471/471cpeua.htm   (3303 words)

 Counterion Triple Layer for Explaining Stirring and Temperature Effects on pH Measurements
This paper reports the pH glass electrode potential based on the double capacitor theory and a new, novel concept of mobile countertion triple layer next to the double layer to explain the electrode potential changes caused by stirring and temperature.
In a basic solution, the electrode is negatively charged, at the interface, the counterion cations will compensate the electrode potential resulkting in a less negative potential, The stirrignand temperature effects as a function of pH are in a linear relationship as shown in Figs.
The pH glass and the SCE reference electrodes are considered as capacitors, their potentials are related to the capacitance potentials, E = q/C. This counterion triple layer is the one containing counterions next to the double layer and may be removed by stirring and temperature.
www.weissresearch.com /TripleLayer.htm   (1864 words)

 C - Glossary of chemical terms
Calomel electrode (calomel half cell) is a type of half cell in which the electrode is mercury coated with calomel (Hg Cl
Cathode is a negative electrode of an electrolytic cell; to which positively charged ions (cations) migrate when a current is passed as in electroplating baths.
In a primary or secondary cell (battery or accumulator) the cathode is the electrode that spontaneously becomes negative during discharge, and form which therefore electrons emerge.
www.ktf-split.hr /periodni/en/abc/c.html   (0 words)

 pH electrode potential
Potential measured by pH meter is a sum of all potentials present in the system.
Second source is the glass electrode silver wire covered with AgCl and immersed in the solution of chlorides, and third is the reference electrode - silver chloride or calomel, depending on the application.
Carefully choosing potentials of both reference electrodes (which can be done with selection of chlorides concentration) it is possible to compensate for all other sources of potential in the electrode so that isopotential point is at pH=7.0.
www.ph-meter.info /pH-electrode-potential   (478 words)

 Electrode Potential and Galvanic Corrosion
The absolute potential of the anode and cathode cannot be measured directly.
Defining a standard electrode, all other potential measurements can be made against this standard electrode.
If the standard electrode potential is set to zero, the potential difference measured can be considered as the absolute potential.
www.engineeringtoolbox.com /electrode-potential-d_482.html   (0 words)

 New Jersey Scuba Diver - Artifacts & Shipwrecks - Conservation of Metals - Preliminary Steps
Metals that have a potential more negative than hydrogen in a galvanic cell are said to have a negative electrode potential, and metals having a potential more positive to hydrogen have a positive electrode potential.
The more negative the electrode potential, the more active the metal, and the greater the tendency for the atoms to lose electrons and form positive ions which go into solution.
As a blanket explanation for the corrosion of different metals in a shipwreck in salt water, the large galvanic cell metaphor and the electromotive position of the metals have been overused and are not completely understood.
www.njscuba.net /artifacts/cons_09_metals.html   (6249 words)

 Standard Electrode Potentials
After studying this section, you will (a) know the meaning of the term "standard electrode potential", (b) understand the relationship between the electromotive force of a cell and the standard electrode potentials of its half cells, (c) be able to use a table of standard electrode potentials in order to calculate the e.m.f.
The cell potential (emf) of this cell under standard conditions is 1.10 V (volt).
The emf of the cell (1.10 V) is the potential difference between the electrodes of the cell, which is the difference between the abilities of the half-cells to attract electrons.
www.physchem.co.za /Redox/SEP.htm   (650 words)

 Engineering > Electrochemistry > Preview > Potential Sign
Looking at the Cu electrode, if the external circuit were closed and current were passed, the result would be that Cu ions migrated toward the electrode where they would be reduced to Cu metal as electrons flowed through the circuit from the zinc to the copper electrode.
So if we simply imagine the copper electrode as having some adsorbed cupric ions on the surface, this is consistent with the spontaneous tendency of the cupric ions to move toward the copper electrode and the result is a positively charged electrode.
The opposite process would be happening at the zinc electrode where the spontaneous tendency is for zinc ions to migrate away from the surface of the electrode, leaving the excess electrons on the zinc metal.
www.engineering.teleactivities.net /electrochemistry/preview/potential_sign.html   (509 words)

 The Hydrogen Electrode
The hydrogen electrode may be abbreviated SHE, NHE, or RHE.
The Standard Hydrogen Electrode (SHE) is officially the 0.0V thermodynamic reference point for all potential measurements.
The Reversible Hydrogen Electrode (RHE) is a fairly practical and reproducible electrode "standard." The term refers to a hydrogen electrode immersed in the electrolyte solution actually used.
www.consultrsr.com /resources/ref/hydrogen.htm   (498 words)

 Glosssary of Corrosion Related Terms
The slope (dE/di) at the corrosion potential of a potential (E)/current density (i) curve.
A term used in the automotive industry to describe the corrosion of vehicle body parts due to the collection of road salts and debris on ledges and in pockets that are kept moist by weather and washing.
The potential corresponding to the maximum active current density (critical anodic current density) of an electrode that exhibits active-passive corrosion behavior.
www.corrosionsource.com /handbook/glossary/op_glos.htm   (1628 words)

 [No title]
To draw up a scale of electrode potentials, choose one half cell as a fixed standard and measure other half cells against it.
If potentials at electrodes kept constant (use reference electrodes), cell EMF becomes indicator of membrane potential at various ion concentrations.
Polarography uses mercury droplet electrode that is regularly renewed during analysis.
www.resonancepub.com /electrochem.htm   (1320 words)

 Voltaic Cells   (Site not responding. Last check: )
In the diagram the electrodes are on the outer side of the diagram and a forward slash (/) is used to separate the electrode from the electrolyte solution found in the compartment.
Standard Reduction Potentials are the voltage generated when a half cell of a certain substance is connected to a reference half cell compartment.
The standard reduction potential for Co is -.28 v and the standard reduction potential for Au is +1.50 v.
members.aol.com /logan20/voltaic.html   (2559 words)

Since hydrogen electrode has the potential of 0.00 Volt, hence potential of Zn electrode is 0.76 Volt.
it is oxidized and it is anode and it is negative with respect to hydrogen electrode.
The standard oxidation potential of zinc is therefore + 0.76V.
www.citycollegiate.com /electrode_potential02.htm   (188 words)

 PinkMonkey.com - Chemistry Study Guide -9.6 Electrode Potential
Electrode Potential is denoted as EMF (electro motive force).
Potential of a single electrode cannot be measured directly.
It is measured by connecting reference electrode (with known electrode potential).
www.pinkmonkey.com /studyguides/subjects/chem/chap9/c0909601.asp   (126 words)

 Fluoride Electrode Measurements   (Site not responding. Last check: )
An external reference electrode must be used to perform the measurement.
Assuming that a saturated calomel electrode is used as the external reference, the potentiometric cell may be represented as
Sources of error include fluoride ion activity changes due to the ionic strength of solution, temperature, which can effect the measured potential through the Nernst equation which governs the electrode potential response and through the several equilibria that fluoride may have with species present in solution, and substances that complex fluoride in solution.
www.chem.usu.edu /~sbialkow/Classes/565/fluoride.html   (1025 words)

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