# What is Electrochemical: Definition and 65 Discussions

Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electrical potential as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving between electrodes via an electronically-conducting phase (typically, but not necessarily, an external electrical circuit such as in electrolessplating), separated by an ionically-conducting and electronically insulating electrolyte (or ionic species in a solution).
When a chemical reaction is effected by a potential difference, as in electrolysis, or if electrical potential results from a chemical reaction as in a battery or fuel cell, it is called an electrochemical reaction. Unlike chemical reactions, in electrochemical reactions electrons (and necessarily resulting ions), are not transferred directly between molecules, but via the aforementioned electronically- and ionically-conducting circuits, respectively. This phenomenon is what distinguishes an electrochemical reaction from a chemical reaction.

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1. ### Can Electrochemical Degreasing be Affected by Chlorides and Soap?

Hi, Why contamination of the bath for electrochemical degreasing by chlorides or soap adversly affects degreasing of parts? What's the difference if chlorine is produced instead of hydrogen or oxygen? I thought that this gases only help the grease to break away from the part's surface. I'm...
2. ### Chemistry Calculate the activity of the chloride ion in a solution

Hi everyone! I have to calculate the activity of ##Cl^{-}## I have a solution formed by ## Na_{2}SO_{4}## 0.0016 m + ##NaCl## 0.0014m + ##FeCl_{3}## 0.0012m I calculated the ionic strength ##I## ##I=0.0134## The activity of the chloride ion is ##a_{Cl^{-}}=m_{Cl}*\gamma _{Cl}## But I don't...
3. ### Chemistry Is bronze tarnish electrochemical corrosion or chemical corrosion?

I can't figure it out.
4. ### Galvanic cell - open circuit voltage and EMF

Hi, having not a deep knowledge of electrochemistry I've some doubts about processes involved in a galvanic cell. Take for instance a Zn/Cu Daniell cell for which E0cell is 1,10V. That means emf for it is 1,10V. Starting to read from how battery works I had a first understanding of how...
5. ### Potentiostat and powersource in electrochemical cell

Hi, Could someone please explain to me some terminology. Is a potentiostat considered a "power source" for an electrochemical cell (the cell is for the CO2 reduction reaction). An example of this type of cell can be seen here...
6. ### Relation of Charge polarity and voltage polarity

Homework Statement What is the relationship of charge polarity and voltage polarity? I understand an anion has negative charge and cation ion has negative charge, but does an anion have a positive voltage and the cation have a negative voltage? Given the above is generally true, when is the...
7. ### Electrochemical overpotentials (V3+/V4+ redox)

Hey, Does anyone know a good source for overpotentials on carbon / graphite electrodes? Especially looking data for V4+ + 2H+ + e- <-> V3+ + H2O (+0.34V vs. SHE) overpotential. Or are there any ways to estimate the overpotentials? Thanks
8. ### Reference Probes in pH and other electrochemical measurements

I am amused by how skillfully most of the texts I have avoid discussing reference electrodes in electro-chemical measurement-They simply start out by discussing the H2 and Calomel electrodes with no further explanation. Both have certain hazards and seem overly complicated. So--why are these...
9. ### Polyolefin Ion Membranes in Electrochemical Cells

Hi, I was wondering if any old polyolefin membrane would work as a separator in an electrochemical cell, or if there is only a special "porous" version. For example, would a grocery store sack (polyethylene) work. It is my understanding that polymers of this sort are naturally porous...
10. ### Hello, i with lab equipment for electrochemical harvesting of microalgae

Hello, I'm an Aquaculture Engineering student at lima. I'm trying to do an experiment of electrochemical harvesting of microalgae. But it seems my weakness at physics its getting in the way plus i don't know to well how to operate the equipment which none knows either since its new to the lab. I...
11. ### Using electrochemical hydrogen compressor in reverse

Electrochemical hydrogen compressors (https://en.wikipedia.org/wiki/Electrochemical_hydrogen_compressor) basically convert an electrical potential difference into a pressure difference. Would it be possible to run one of these in reverse, i.e. using a pressure difference to create a voltage? If...
12. ### Solution Potential Witout Electrodes (Pourbaix diagram help)

http://C:\Users\jason\Desktop\Research Summer 2016\cucl pb.PNG I am currently attempting to use SEA to plate CuCl2- on to the surface of a magneli phase Titanium oxide membrane. I can roughly rationalize the y-axis and how it functions when there is an electrochemical cell (follow OCP), and how...
13. ### Exploring the Future of Fuel Cells: A Ph.D Student's Perspective

Hi My name is Mesut. I am a Physics Ph.D. student at University of Arkansas at Little Rock. I am working on Fuel Cells. Thanks
14. ### Explaining The Non-Reaction Of An Iron Nail With Equilibrium

The question asks: Recall that you observed very little corrosion occurring on the iron nail immersed in NaOH(aq) solution. This observation is difficult to explain from an electrochemistry perspective since electrochemistry principles predict a spontaneous reaction that should cause...
15. ### High Temperature electrochemical measurements

Hi all, I'm interested in high temperature sample holders of electrochemical measurements especially for Li-ion batteries. But I couldn't find one. Does anyone use it before? Best regards
16. ### 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...
17. ### Electrochemical potential and negative Hall resistance

Homework Statement In the case of the b trajectories, I want to understand why the electrochemical potential at voltage contact 3 must be the same as the current contact 4. And can you say anything about the electrochemical potential inside the sample itself? Homework Equations - I know...
18. ### Electrochemical Cells (involving partial pressures and pH)

Homework Statement A voltaic cell utilises the following reaction: 4 Fe2+(aq) + O2(g) + 4 H+(aq) ---> 4 Fe3+(aq) + 2 H2O(l) What is the emf of this cell when [Fe2+] = 1.3 M, [Fe3+] = 0.010 M, PO2 = 0.51 bar and the pH of the solution in the cathode is 3.5. The standard reduction potentials...
19. ### What is the importance of the solution in an electrochemical cell?

I'm wondering about the importance of the electrolytic solution in an electrochemical cell. For example, we have Zn/ZnSO4 and Cu/CuSO4. According to the electrochemical series, Zn will reduce Cu, and we will have a reaction. Zn(s) -> Zn2+(aq), Cu2+(aq) -> Cu(s). So there MUST be Cu2+ in the...
20. ### Schools Graduate school for Materials Engineering? (Electrochemical?)

Hello, I need some help trying to decide my future degree. Any comments would be appreciated! My History: I want to dedicate my career innovating Electrochemical technologies (Fuel Cells, Batteries, Solar Cells, etc...). Before entering college, I originally applied as a "Chemical...
21. ### Chemical reaction of electrochemical etching

Greetings all, I have some questions regarding to chemical reaction between Silicon,Si (wafer) and chemical dissolution. FYI, I'm doing electrochemical ething to fabricate porous Si. Could anyone help me to solve this chemical reactions? 1) Si (silicon wafer) + HF (hydroflouric acid)+...
22. ### Me With An Electrochemical Cell and Equivalence.

Hi, Please don't be spooked by the long post, it's just that it contains two problems (I beg your pardon if I shouldn't have put both in one post, I just figured it'll be better than creating two posts...). I can't figure how to solve these, so if you please could please help me with...
23. ### Electrochemical reduction of Hydrogen forms hydride?

Would the electrochemical reduction of H2 form Hydrogen Anions of H- H2 + 2e- -> 2H- If this is the case, is the following true? H- + (1/2)H2 -> H2
24. ### Difference between electrochemical equilibrium and chemical equilibriu

1. What is electrochemical equilibrium and what is chemical equilibrium? 2.What are the differences between the two above? 3. The difference between the two i think is electrochemical equilibrium is a state whereby the electrical charge in both compartments are equals. Wherease...
25. ### Why is the potential changing in my electrochemical cell setup?

I took some phosphate buffer saline(7.4) into a beaker, included a Au electrode and reference electrode (Ag/AgCl) and tried to measure the potential using multimeter. The temperature and pressure is assumable same. The multimeter shows the potential some milivolts but the potential is decreasing...
26. ### Difference between Voltage Bias in STM/STS vs. Electrochemical Cell

Hello Everyone, I am a student studying electrochemistry – specifically energy storage devices. I have been familiarizing myself with various techniques to characterize the electrode surfaces. In particular, I am interested Scanning Tunneling Microscopy (STM) / Scanning Tunneling Spectroscopy...
27. ### Electronegativity vs electrochemical series

Carbon is higher in the electrochemical series than hydrogen, which indicates it is more electropositive, but Pauling values show carbon as more electronegative - 2.55 vs 2.2!? Any reason / explanation for the apparent contradiction? Tried looking for an Eo value for C (should be more...
28. ### Is Farady's law applicable to electrochemical cell

Farady's law are derived for electrolysis. My question is the same rule can be applied in the analysis of electrochemical cell? I think those two cell (electrolytic and electrochemical) are just opposite functional to each other.
29. ### What makes electron flow in an electrochemical cell

So, here is my question we know about an electrochemical cell in which when zink rod and copper rod are dipped in there respective solutions the electron flow from zink rod to cu ... but what makes those electron to flow ... here comes the answer the potential difference did that ... please...
30. ### Somewhat wierd question for Elec Eng.Nickel plating and electrochemical equivalents

1.A plate is to be nickel-plated to a thickness of 0.15mm in three and a half hours. The electrochemical equivalent of nickel is 0.305mg/C and the density of nickel is 8778kg/m^3 .Calculate the surface area of the plate that can be plated to the specified thickness with current of 12.4Amps...
31. ### Electrochemical cell question - strip on Zn in contact with zn2+/CN solution

The potential at which a metal is deposited in the electrowinning process can significantly affect the quality of the deposit. The potential itself can be dramatically affected by the addition of complexing agents and by adjusting the pH of the solution as the following calculations demonstrate...
32. ### Electrolysis (Chemistry) with electrochemical cell

How does concentration of solution (So42) affect the voltage in a electro-chemical cell?
33. ### Can this electrochemical reaction be explained? Steel, copper and electricity

My son brought home a fourth-grade science experiment a few days ago: He was to make some sort of property change in a steel nail. He had decided that he wanted to make it rust, so we set about creating an electrolyte solution out of salt and water and leaving it in there. There wasn't...
34. ### Voltage of electrochemical cell

hi i was wondering if somebody of you knows something about this stuff? it is about an electrochemical cell that is made of zinc and copper in sulfuric acid. now the reaction is: Zn-> Zn(2+)+2e- 2H+ + 2e- ->H2 my problem is, that i do not know whether this...
35. ### Solving the Nernst Equation for Zn^2+ Concentration

I built a cell with one side containing the solution 0.10 M CuSO4 with Cu(s) in it. The other side has 1 M NH3 and 0.05 M ZnSO4 with Zn(s) in it. The measured cell potential was 1.31. I am using the Nernst equation. I need to find the concentration of Zn^2+. E=E"-(0.059/2)logQ 1.31 =...
36. ### What ions produce a 2.00 V potential in an electrochemical cell?

Homework Statement Based on the following chart, what ions would you use to construct an electrochemical cell with potential closest to 2.00 V? [PLAIN]http://img546.imageshack.us/img546/5568/electrochemicalcellchar.png Homework Equations I know that I am supposed to add the voltages of...
37. ### Charging an electrochemical capacitor

I have a very basic question confusing me about charging electrochemical capacitors - When you charge a symmetrical electrochemical capacitor to 1V, because one electrode becomes positively charged and the other negatively charged, the electrode potential across one will be +0.5V, and the...
38. ### How to build a circuit for an electrochemical to extract different metals

Hello All, I am trying to build what is essentially an electrochemical cell which I will use to filter waste water and try to recover gold silver and copper among other metals on a High Surface Area Cathode like Carbon.I want this electronic filter to be selective about the metals recovered...
39. ### Can an Electrochemical Cell Without a Conductor Produce Voltage?

Homework Statement let's say we have an electrochemical cell composed of 2 cups each cup contain a metal and the ions of that metal and an acidic componment like H2so4 the two cups arent attached with any kind of conductor if we try to measure the voltage with a voltmeter would it detect...
40. ### Solving Confusion: Ashcroft & Electrochemical/Chemical Potential

Hello. There is no agreement on the meaning of terms electrochemical potential and chemical potential (see for example http://web.mit.edu/6.730/www/ST04/Lectures/Lecture26.pdf"). While proper definitions would call chemical potential to \mu\equiv\left(\frac{\partial U}{\partial...
41. ### Solving a Voitaic Cell: 0.45V Electrochemical Potential

Homework Statement A voitaic cell consists of a Zn/Zn^2+ half-cell and Ni/Ni^2+ half-cell at 25C. The initial concentration of Ni^2+ and Zn^2+ are 1.50M and .100M respectively. What are the concentrations of Ni2+ and Zn2+ when the cell potential falls to 0.45V? Homework Equations...
42. ### Electrochemical Cells - oxidants and reductants

In an electrochemical cell involving copper and magnesium copper gains electrons (is the oxidant) and Magnesium the opposite. I understand that Cu is the least reactive of the two electodes and therefore the Mg gives up electrons to stop the Cu from oxidising, but why does this difference in...
43. ### Electrochemical cells: Is gibbs free energy dependent upon concentration?

Is the gibbs free energy of some reaction in an electrochemical cell dependent upon reactant concentration? The Nernst equation clearly states that open circuit potential is dependent upon concentration, and basic thermodynamics states that open circuit potential is directly proportional to...
44. ### Are Electrochemical Gradients the Driving Force for Ion Movement?

Or, the combination of a chemical gradient and an electric gradient. So suppose you have a postsynaptic membrane. The postsynaptic space is negatively charged, but it also has a huge number of Na+ ions relative to the extracellular space. So if you open up a channel, the electrical gradient...
45. ### Electrochemical Cells, Cell Potentials: Using Nernst Equation

Homework Statement The standard reduction potentials for Ni2+ and Sn2+ are as follows: Ni2+ + 2e− → Ni E° = −0.23 V Sn2+ + 2e− → Sn E° = −0.14 V Calculate the equilibrium constant at 25°C for the reaction Sn2+(aq) + Ni(s)→ Sn(s) + Ni2+(aq) Homework Equations Nernst...
46. ### Recharging an electrochemical cell

If you want to recharge an elctrochemical cell, which electrode do you supply with more electrons? My thinking was: There was a P.D. between the elctrodes but now that the cell is spent, the P.D. is lower. To create a P.D. again, you must make the negative electrode more nagative or the...
47. ### Gradient (Electrochemical, proton, ion, etc)

I just started learning about cellular respiration and I'm not clear as to what the word "gradient" means. I see it tied to many terms such as electrochemical gradient, proton gradient and ion gradient. Is a gradient just a space or "field" with varying concentrations of something (protons...
48. ### Electrochemical investigations using a three electrode system

Hi, I am trying to understand what's going on in a standard three electrode system such as one used in cyclic voltammetry and the functions of each of the electrodes. I.e What role does the Working, Counter and Reference electrodes play? The conclusions iv'e come to so far is that working...
49. ### Electrochemical Cell | 75W Bulb | 50min | 12V Battery

Homework Statement A 75.0-W light bulb is powered by connecting it to a standard 12.0 V auto lead-storage battery. How much energy (J) is required to keep the bulb burning for 50.0 continuous minutes ? Assume 100 percent efficency.Homework Equations 1 watt = 1 J/s 1 J = 1 C x 1 V The Attempt...
50. ### RC Charge/Discharge for Electrochemical Capacitor

I am a student working on designing an electrochemical capacitor (an area which i have limited experience). When I charge this capacitor through an RC circuit I notice two non ideal effects. I need to adress the cause of these effects if I can ever hope to correct them. The first problem is...