What is Electrode: Definition and 89 Discussions

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). The word was coined by William Whewell at the request of the scientist Michael Faraday from two Greek words: elektron, meaning amber (from which the word electricity is derived), and hodos, a way.The electrophore, invented by Johan Wilcke, was an early version of an electrode used to study static electricity.

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  1. M

    Voltaic cell + battery in series

    Hello, I wanted to know if connecting a battery in series with a voltaic cell would increase the rate of the redox reactions. Let's take the simplest example of a voltaic cell constituted by a Zn/Zn2+ half-cell connected to a Cu/Cu2+ half-cell. When the circuit is closed, the Zn electrode will...
  2. mksrm

    Voltage and electrode surface area

    Hi I am looking to find the equation that determines the minimum (and if possible maximum that might damage the electrode) voltage that starts the electrolysis process for a given area of a graphite electrode in a brine solution medium (lets say 30%) at equilibrium state. Also how does the...
  3. Wrichik Basu

    I Understanding iris electrode and iris doublet (Accelerator physics)

    Iris electrode The potential distribution in the vicinity of the iris electrode, denoted by ##V(r,z)## is rotationally symmetric. After some derivations, the author arrives at the following two equations: $$\begin{align} E_z &= - V'_0(z)\\ E_r &= \frac{1}{2}V''_0(z)r, \end{align}$$ where...
  4. Dario56

    Definition of Absolute Electrode Potential

    Hey guys, I have two questions: 1) I thought absolute electrode potential is galvani potential difference at the interface. However, it is given by this equation in John Bockris - Modern Electrochemistry: $$ E(abs) = ^M\Delta^S\phi - \mu_e^M/F $$ First term is galvani potential difference on...
  5. Dario56

    Understanding the Role of a Voltmeter in Electrode Potential Measurement

    Voltmeter is an instrument which measures electric potential difference between two points. When measuring electrode potential of some redox system (vs SHE for example), it is said that voltmeter reading contains sum of all potential differences present in a cell. This includes all...
  6. uzi kiko

    Electrolysis using a single electrode

    Hello Inspired by this video, I wondered if it was possible to create a process of electrolysis in saltwater using a single electrode. To my understanding (Please see the attached diagram), if a direct current passes through I2 (after the diode) a direct current must also pass through I1...
  7. J

    Uniform Field Gap (Rogowski profile) Electrode Design

    Hi, I am interested in designing an electrode that reduces the peak e-field intensity at the edges of the electrode. I've read some papers and it looks like there are quite a few. I'm not really familiar with the terms, so I decided to start off with what looks like is one of the simpler ones...
  8. HelloCthulhu

    Charge Capacity of an Electrode Based On Its Material

    Recently I've been researching parallel plate capacitors and was wondering what effects the material had on the charge capacity of the plate. I found one source for measuring the capacity based on its material, but haven't seen any textbook evidence to support it yet. Any feedback on the...
  9. E

    Interfacial PDs vs Electrode Potentials

    Consider the cell ##Pt | H_2 | H^+ || Ag^+ | Ag##. I’ve sketched the electric potential against distance across the cell: I would think the electrode potential of the ##Ag+/Ag## electrode is ##V_{Ag+/Ag} - V_{H^+/H_2}##, which I’ve labelled on the right. We set ##V_{H^+/H_2} = 0## as per...
  10. E

    Interpreting Electrode Potentials

    My teacher insists that the reverse reaction has a negated electrode potential (oxidation potential?). This doesn’t make sense to me, since I am under the impression that the electrode potential is a property of the half cell at equilibrium and not of either of the reactions in a particular...
  11. D

    Do these half-reactions have electrode potential that depends on pH?

    Do following half-reactions have electrode potential that depends on pH? I know H+ or OH- ions wouldn't be included in Nernst equation for these, but would pH affect chemical balance in these reactions, and therefore electrode potentials? Br2+2e- -> 2Br- Cl2+2e- -> 2Cl- I2+2e- -> 2I- S2O8+2e-...
  12. P

    Calculating a Non-Uniform Electric Field Given 6 different Electrode Pairs

    I know how to find the electric field of more traditional designs i.e. a sphere, through Gauss' Law but I don't think Gauss' Law applies to this scenario. I tried to separate each part of the electrode into simple spheres and rods and using Gauss' Law to find these individual elements. This...
  13. fsonnichsen

    Electrode Polarization and Conductivity

    The common mantra is that when measuring conductivity in solutions the electrodes will build up a polarization layer and disturb the measurement, thus a 4 electrode measurement is used and an alternating current impressed up on the outer electrodes, usually around 1000 hz. I have been trying to...
  14. S

    Minimum breakdown voltage in Neon, Electrode spacing in mm

    Hello all. I am conducting a simple research project, and am having a little trouble with the math for paschen's law. my question is. At 74762 Microns of pressure, using pure Neon gas, what is the electrode spacing in mm for the minimum breakdown voltage of that gas? Thank you.
  15. B

    Unknown Electrolysis(?) reaction occurring

    I have obtained an experimental setup of a Marx bank which has electrolytic liquid resistors. In the tubing of the resistors are various strength solutions of copper sulfate. I was told that the electrodes are copper but there appears to be some sort of plating or other reaction occurring...
  16. E

    Which reference electrode to select?

    Hi. Is there any significant difference in quality and accuracy between reference electrode with Vycor frit (porous glass attached with heat-shrink tube) and the one equipped with ceramic frit (molten in the glass tube) like in this example...
  17. R

    Is a gold electrode supposed to corrode during electrolysis?

    Help! I was under the assumption that a gold electrode for oxygen would be able to sustain water electrolysis with sodium bicarbonate as the electrolyte without degrading, so I bought a foot long of 28 gauge 24k(pure gold) wire, but I've been putting it to the test for about 30 minutes and it's...
  18. T

    Standard electrode potential vs ionization energy

    Here is the Wikipedia page on electrode potentials. Here's how I'm reading it, which makes no sense: If a singly ionized atom of strontium donates an electron to the hydrogen in the standard hydrogen electrode, this will emit 4.101 eV of heat (395.68 kJ/mol). If cesium is used, there will be...
  19. MichaelLAndersonEE

    What is deposit on palladium electrode?

    I am not an electrochemist, but I do need to understand various issues with an analytical chemistry instrument. This is a somewhat open-ended question. The instrument applies a voltage waveform across two palladium electrodes. Typical waveform is 2 Hz, 4 Vpk sinusoid, for brief intervals...
  20. S

    Electronics DIY Stun Gun/Electrical Stimulator

    I am doing nerve conduction research for the Intel International Science Fair and I need to make a stimulating electrode or just something that I can make with common items and that can release enough voltage to stimulate/activate the nerve. I made one using a lighter, but I am not sure that it...
  21. hackhard

    Water Surface Touch Pad: Can My Project Work?

    an idea for my new project construction - a cubical bowl of tap water , 2 sheet electrodes for 1 pair (y-axis pair)of opposite face(square wave 10Hz 10vpp), 2 sheet electrodes for the other pair (x-axis pair)(similar square wave lags by half cycle ) left hand touches adc pin. right hand touches...
  22. Conductivity

    Why do we use electrode potential to predict other reactions

    Probably the title wasn't really clear. What I am asking for is an explanation. Isn't the potential of the electrode is created by a combination of ions and electrons? and we can't possibly measure the absolute potential. However, we can measure it relative to other electrodes such as hydrogen...
  23. T

    Potential of hydrogen electrode

    Homework Statement Homework EquationsThe Attempt at a Solution From the calculation of the potential of the cell and the potential for the copper electrode, it states that the hydrogen electrode has a potential of -0.09 V. But I thought hydrogen electrode is standard so it should be zero...
  24. A

    CNT electrode CCTO dielectric supercapacitors?

    Will the high surface area of carbon nanotubes and high dielectric constant of calcium copper titanate be used together in supercapacitors?
  25. L

    A Image force in normal metal electrode tunneling

    Hi there, I have a question that I think has an answer but I cannot find it in the literature in any convincing way: I am using two models, WKB based and TMM based to calculate the transmission probability of electrons through a (initially rectangular) thin potential of the order of 1-2nm...
  26. L

    Glass electrode voltage calibration and pH analysis.

    Hi, I'm stuck on part b) of the question below: Q: In order to perform pH determinations with a glass electrode, the cell potential was measured for threestandard solutions with the following pH values at 25 C: 2.04, 7.05, and 9.20. The cell voltage readout(in mV) for each of the above solutions...
  27. P

    Electrolysis of water and actual electrode potential.

    For an electrolytic cell, the voltage source Vs, does not contribute directly to the potential on the electrolytic electrodes. Vs determines the current and can add charges to the electrodes. This can be observed when charging supercapacitors and is discussed in these threads ...
  28. R

    Water electrolyser electrode material

    I've been trying to build a closed system water electrolyser with easily available materials which allows me to collect the gases separately. To do so, I've been meaning to build an acrylic housing with a textile separator in the middle of two compartments which houses the anode and cathode. The...
  29. N

    Li ion battery electrode surface area

    What effect (if any) would changing the surface area of electrodes in a lithium ion battery have? Would it allow for faster battery charging? Faster discharge rate? Thanks in advance
  30. S

    Graphite electrode destroyed in electrolysis

    I built a Hoffman apparatus with graphite electrodes. I hooked it up to a make shift power supply from an xbox powerblock. It was filled with battery acid for the electrolyte. Now, the graphite electrode is 99% graphite rod. For some reason the graphite electrode on the negative(black)...
  31. AnkurGarg

    Electrochemical cell electrode potential difference

    In our textbook it is written that -voltmeter measures the electrode potential difference between 2 half cells (in an electrochemical cell) (electrode potential refers to the potential difference between electrode and its salt solution in which it is dipped) it should come-voltmeter measures...
  32. C

    Why is the central electrode in a G.M. tube positive?

    Why is the central electrode in a Geiger-Muller tube always positive (and not negative)? Many thanks!
  33. D

    Why doesn't electrode potential depend on amount of metal?

    When a metal (electrode) is in contact with water, an equilibrium forms: Mg ⇔Mg2++e- Adding more of the metal Mg should convert some of it into more electrons so that the ratio of Mg to Mg2+ remains the same (as the equilibrium requires). Therefore twice the amount of metal in contact with water...
  34. L

    Current density uniformity electrode array

    Hi All, I'm working on a research project that requires putting an electrode array with 4 elements into a flexible tube filled with conductive liquid. The electrode array is a series of balls, with the first being positive and the last being negative. The idea is to measure the change in...
  35. T

    Understanding Three Electrode System Interactions

    Hello, I have two doubts. In a three electrode system, do the reference electrode and the auxiliary electrode interact (by direct contact or other way) with the analyte? And why? The second doubt consists in this point and I think is connected to half of the previous question: during for...
  36. AdityaDev

    Electrochemistry: reference electrode

    Reduction half reaction : Cu2++2e- -> Cu(s) I have a doubt in using the reference electrode. For example if I have the calomel electrode (ESCE=0.24V) how do I use it with the copper half cell? Are these reactions correct? Cu2++2e- -> Cu(s) 2Hg+2Cl -> Hg2Cl2+2e- To get Ecell=0.24+ECu|Cu2+
  37. S

    Hydrogen electrode incoherence?

    Today I was studying Atkins physical chemistry basics and I saw a bit of incoherence. ΔrG°=ΔrH°-TΔrS° ΔrG°=ΔfG°(products) - ΔfG°(substrates) ΔrG°=nFE° Data: ... ΔfH° ... ΔfG°...ΔS°(J*K*mol-1) H2(g)...0......0......130,684 H+......0.....0.....0 2H+(aq) 2e- => H2(g) Using second and third...
  38. marcophys

    HT 'low current' resistance fundamentals in Tungsten Welder - event horizon

    Does anybody understand the fundamentals of what is happening in this circuit? Tungsten welding info is all about high current... but this is a low current scenario. AC input, CDI Coil generated 20Kv (estimated) suffers voltage drop over 100mm of tungsten rod. The larger the diameter... the...
  39. S

    Li-ion battery positive electrode attraction

    I don't understant how the positive electrode can attract both electrons and the positive Li ions as they both flow to it. Also, the way to start the whole process is to let the electrons flow, right? (Close the circuit.) Without it, the ions also don't want to start flowing, although there is...
  40. G

    Polarized Slab between Parallel Plate Electrode

    Homework Statement Find the electric field everywhere for the following permanently polarized structures which do not support any free charge: (b) Permanently polarized slab P_0 i_x of thickness b placed between parallel plate electrodes in free space at potential difference V_0...
  41. Warpspeed13

    Calculating Electrode Erosion Rate in Arc Gas

    So I'm pretty sure this falls into both the realms of physics and electrochemistry. How would I calculate the rate of erosion of an electrode if it were sustaining an arc in a gas?
  42. S

    Calculation of absolute electrode potential and salt bridge qns

    >According to http://www.chemguide.co.uk/physical/redoxeqia/introduction.html each electrode has an absolute electrode potential which is the difference between the positiveness and negativeness. So if we had a Zn plate in water and it has a negative charge of -5 on the metal. Would the absolute...
  43. marellasunny

    Smaller electrode gap implies misfire;why?

    My book says smaller the electrode gap,greater the chances of a misfire. The reason stated is that this is because of a smaller activated volume. I understand the meaning of misfire: it is when electricity takes a different path due to electrically conductive residue lying between electrode...
  44. A

    ECG/EMG Electrode Measurement

    I need to collect data via measuring EMG signals in the upper arm. I have standard AgCl stick-on ECG electrodes. My question is, if I can use normal alligator clip cables for collecting this signal from the electrode and feed it into an instru-amp? Will this affect the signal strength and/or...
  45. Z

    Calculating electrode current density

    This is more electrical engineering than chemistry I would think. If the current density required is 200mA per cm^2, and the electrode is a hollow copper tube that is submersed in an electrolyte in which the inside of the tube is not touching any solution, should the current be calculated...
  46. S

    Using a Platinum Electrode & HCl in a Standard Hydrogen Electrode

    In Standard Hydrogen Electrode why only Platinum electrode should be used and why should it be dipped in HCl?why can't we use any other metal dipped in any other acid other than HCl?
  47. D

    How to quantify fringing fields around a finite width plate electrode?

    Homework Statement This isn't homework or coursework as such, but i thought it may be the best place to ask this question. The last time i posted in the other section it was deleted! Im considering the case of an electrode of finite width L in the x direction. The y direction is...
  48. W

    Deriving potential distribution between concentric spherical electrode

    Homework Statement For some work I am doing I wish to be able to define the potential distribution as a function of the radius (ρ) between two concentric electrodes. Homework Equations One solution (from reliable literature) defines the varying radial potential as: V(ρ)=2V0(ρ0/ρ...
  49. F

    Electrolysing Sodium Chloride: Silver vs Graphite

    If I was to electrolyse a hot sodium chloride solution I'm pretty sure a copper electrode would react to make copper chloride. Whereas I would have used graphite electrodes if the solution was cold, this reaction should produce sodium chlorate which can obviously be quite reactive with organic...
  50. B

    Electrode Potential: Establishing E & Measuring Ecell

    Am I right to think that the potential established at an electrode immediately when placed in solution is given by E = E° - \frac{R \cdot T}{F} \cdot log_e(Q_{surface}) where the potential E of the electrode results from the standard electrode potential (E°) of the reaction and the reaction...