Questions tagged [electrochemistry]

The branch of chemistry that deals with the study of redox reactions and how they can be applied to generate electricity (in electrochemical cells) and to carry out non-spontaneous reactions using electricity (electrolysis).

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17 views

Which is a better electrolyte? PLEASE HELP

I need to know which is a better electrolyte to use when electroplating copper, is copper sulphate or copper nitrate better? PLEASE HELP ASAP
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Does anyone know a database that shows the effect of electrolyte concentration on the production of hydrogen gas during electrolysis of water?

I'm currently studying in the International Baccalaureate model. This high school model asks their students to do an individual work called the Internal Assessment. One of the subjects I study is ...
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Can I use an electrolyte containing a different cation from the anode when doing an electroplating experiment?

For example, I want to purify copper. So the anode will be impure copper and cathode will be pure copper. However, instead of using copper sulphate/halides/nitrate solution, can I use magnesium ...
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A question about potential difference across a membrane

Membrane potential of living cells arising from the difference of concentration of ions on both sides of the membrane, but why didn't someone use selective polymers as AEM (Anion Exchange Membrane) ...
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Why isn't Mg deposited on the cathode after electrolysis?

Well here's a question from my book: A solution containing one mole per liter of each $\ce{Cu(NO3)2}$, $\ce{AgNO3}$, $\ce{Hg2(NO3)2}$ and $\ce{Mg(NO3)2}$ is being electrolysed by using inert ...
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27 views

Solution for Electroplating Selenium?

I need to electroplate selenium onto a conductive metal (for an experiment). The end goal is a thin film of pure, elemental selenium. Unfortunately I can't find anything on the internet: Ideally, I'd ...
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1answer
35 views

Redox flow battery [closed]

What is meant by decoupling of power and energy in context of redox flow battery? I understand that the electrolyte containing the active ions can be stored in tanks and that adds flexibility in scale ...
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2answers
34 views

How do the two half cells of Daniel cell know when they are connected?

I'm currently studying electrochemistry in school, and there is something I don't can't quite understand about Daniel cell. When you put $\ce{Zn}$ solid into $\ce{ZnSO4}$ solution, does the electrode ...
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3answers
67 views

Balancing redox equations with oxygens in multiple oxidation states

How do you balance this using the ion-electron method; $\ce{CrO5 + H2SO4 -> Cr2(SO4)3 + H2O + O2}$ The oxygen has multiple oxidation states in $\ce{CrO5}$, and none of the sites I looked this up ...
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40 views

Why does increasing the concentration of the salt bridge in a galvanic/voltaic cell increase voltage?

I recently set up an experiment with 1M half cells made up of zinc and copper nitrate. They were connected with a sodium nitrate salt bridge of varying concentrations. As the concentration doubled 5 ...
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41 views

Electrolysis of copper without any copper initially in solution

Let's say we have two copper electrodes as shown in the image, and there is a solution with copper nitrate. In this case, I know that copper will deposit onto the cathode and copper from the anode ...
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How to deal with the unit “Coulomb per equivalent”? [duplicate]

In a question that I came across they defined $1\,\pu{F}$ as 96500 coulomb per equivalent. Now as far as my knowledge is concerned $1\,\pu{F} = 96500\,\pu{C/mol}$. The question involved asks to ...
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Is there a quick way to approximate a logarithm in Nernst equation?

The problem is as follows: In a galvanic cell the cathode is an $Ag^{+}(1.00\,M)/Ag_{(s)}$ half-cell. The anode is a standard hydrogen electrode immersed in a buffer solution containing $0.10\,...
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2answers
48 views

Why does the oxidizing strength of the chlorates decrease with increasing oxidation number?

Here is a table of the standard reduction potentials of the chlorates from wikipedia: Intuitively, one would expect that the more positive the oxidation state, the more oxidizing that compound would ...
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Why is the ionic product of water $K_w$ the same in acid, water, and alkali?

Seen on the web: The concentration of [H+] and [OH−] both vary based on the the composition (acid/alkaline) of the solution, but the remarkable thing is that their product does not. When [H+] goes ...
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1answer
45 views

Electrode potentials vs interfacial potential differences

Between an electrode and an electrolyte there exists an interfacial potential difference. Many authors give the electrode potential to be the electric potential of the electrode relative to the ...
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37 views

Copper (II) Acetate from 5% vinegar + salt, electrochemically

I'm trying to create Copper (II) Acetate crystals, but in these times of Coronavirus it's difficult to come by hydrogen peroxide. I could be patient, but I'm not, so I'm trying to make it ...
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Why did my voltage decrease when I increased the temperature of my galvanic cell, and increase when I decreased the temperature? [closed]

I used a zinc electrode in a 0.1 M zinc sulfate solution, a carbon rod electrode in a 0.1 M copper sulfate solution and used potassium nitrate for my salt bridge. I measured the voltage at room temp ...
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1answer
77 views

Limiting molar conductivity of multiple solutes

Suppose there is a water solution at $\pu{25 °C}$ with $\ce{Na+},$ $\ce{Mg^2+}$ cations and $\ce{Cl-},$ $\ce{HCO3-}$ anions. Concentrations $[\ce{Na+}],$ $[\ce{Mg^2+}],$ $[\ce{Cl^-}]$ and $[\ce{HCO3-}]...
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65 views

What is the relationship between concentration and voltage in a galvanic cell? How do you calculate the theoretical?

I am a year 12 Chemistry student and I was wondering if you could help me with some questions I have about a Galvanic cell experiment? I am doing an experimental report in Chemistry. The experiment I ...
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43 views

Why is Electrochemistry often the method of choice for determining Ksp values? [closed]

I don't understand the relationship they have with one another. Please, someone explain.
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26 views

What is the electrolytic bath used in gold-plating of copper articles?

The answer is $AuCl_3 + NaCN$ Now I understand that for electroplating, we need gold to be deposited on the copper article, and the electrolyte must enable that deposition. But I don’t know what is ...
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1answer
96 views

Does the order of a written redox couple matter?

My understanding is that a redox couple is an unordered pair of two conjugate species. So we could speak of the redox couple consisting of $Ag$ and $Ag^+$; depending on whether a given redox couple is ...
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Don't understand the formation of Li dendrites regarding Sand's Time

I have a question about Sand' time which can indicate the start of the formation of lithium dendrites. From the paper I'm reading, it defines the concentration gradient in a cell as below. And, ...
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1answer
56 views

Most understandable notation for reduction and oxidation potentials

Nowadays a lot of electrochemistry is done using just electrode potentials (i.e. reduction potentials), so if in doubt the notation $E^o$ tends to imply a reduction potential. However, some chemists ...
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What is the hidden meaning of electrochemical stability window? [closed]

I don't really get the real meaning of the electrochemical stability window. I googled a lot, and the only thing I understand about the electrochemical stability window is that it's the voltage range ...
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2answers
329 views

Will galvanic corrosion happen on a ring made of gold and bronze?

I have recently got a custom-made ring from a jeweler. It’s made from a byzantine-period bronze ring enveloped in a gold bangle. The bronze ring is “glued” onto the gold ring through some kind of ...
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Which is the best kind of filter papers to use to extract silicon nanoparticles after acid wash, hydeophobic or hydrophilic?

I'm looking for filter papers to extract silicon nanoparticles after acid etching. I found that much of my material is get wasted with my Whatman Grade 4 filter paper. I am thinking to use membrane ...
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1answer
18 views

Reaction in Zinc-Carbon-Ammonium Chloride battery

I made a dry cell battery from zinc (Zn), carbon (C) and ammonium chloride (NH4Cl) which produced a current of 0.4 amps and voltage of 1.1V. However when I could not find the redox reaction that was ...
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1answer
248 views

Why do we write electrode potentials next to chemical reactions? [closed]

We might have a half cell consisting of the redox couple $\ce{Ag+}/\ce{Ag}$, which for example's sake might be fixed to be at the cathode (i.e. undergoing reduction). The reaction at the cathode is ...
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1answer
117 views

Computing i0 in the Butler-Volmer equation: How to interpret Wikipedia and Wolfram Alpha

So far, when using the Butler-Volmer equation, I had j0 given and could then just use I = A * j0 * [exp(...) - exp(...)], with <...
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Log(Q) is zero, therefore the effect of temperature change is unaccounted for by Nernst Equation?

I have an internal assessment on Nernst Equation. The experiment is seeing how changing temperature effects cell potential. The solution are zinc and copper sulfate with each having concentration of ...
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4answers
119 views

How Can I Induce Corrosion Electrochemically?

I'm very interested in measuring corrosion in metal alloys, particularly in salt solutions. I understand metals corrode over time, however, I was wondering if it's possible to electrochemically "speed ...
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2answers
2k views

Butler-Volmer equation with concentration dependence?

For a simple elementary reaction on electrode \begin{equation} O+e^-\rightleftharpoons R \end{equation} We can derive the Butler-Volmer equation. But it seems that the formula found on John Newman's ...
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Molecular mechanics of current flow in electrolysis of alkaline water - effect of electrolyte concentration?

I’m confused about the how to explain the effect of electrolyte concentration (eg. NaOH) on the magnitude of the current when an external voltage is applied. I want a precise explanation and not a ...
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1answer
42 views

galvanic cell vs electrolysis [closed]

At school(high school), to calculate the voltage needed for electrolysis, we calculate the voltage produce if the elements were in a galvanic cell, preceded by a minus. So if a galvanic cell with Cu ...
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27 views

What is the Gibbs free energy of Lithium-Graphite and Lithium Cobalt-Oxde

I'm trying to do some hand calculations for Lithium-Ion batteries and I can't seem to find the standard state Gibbs free energy of formation for either Lithium-Graphite or Lithium Cobalt-Oxide. They ...
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18 views

What determines the potential of a half-cell with chemically inert electrode in a solution containing more than one redox pair?

Let's assume we have an electrode made of an inert metal as platinum or gold immersed in a complex mixture containing many compounds (in various concentrations) that can undergo redox reactions. We ...
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24 views

What happens when mixing saline water + sodium-occluding Zeolite?

If the Zeolite occludes the sodium ions and also softens the water. The remaining chloride (from the NaCl) should form Hypochlorous acid with the water? I do realize that the solution needs lots of ...
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1answer
42 views

Electrode potentials in a potentiostat

I am not a chemist but for a university project i am dealing with simulations concerning a potentiostat using a 3-electrode setup. For example in the book Electrochemical Methods (Bard & Faulkner,...
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2answers
12k views

Correct equation for Ionic Conductivity (λ) in Solutions?

We haven't started on Electrochemistry at school yet, but I did manage to find some time to read up on the topic. One thing I've noticed from when I started, is that different books and sites use ...
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How does hydrogen peroxide affect the redox potential of water?

I work in water treatment and we use hydrogen peroxide $(\ce{H2O2})$ to treat levels of ferrous iron and help our coagulant (aluminum sulfate) react better to clump solids. We’re told that generally ...
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Will there be an interference by ions in the salt bridge to current flow, when these have lower electrode potentials?

Research tells that there is no effect of the salt bridge on the current flow or the voltage generated by a voltaic cell, however there seems to be a difference according to the reduction potential of ...
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4answers
354 views

Where to buy/How to build a Devanathan-Stachurski cell?

I'm preparing to do some hydrogen permeation tests to calculate the diffusivity of some iron samples. I would like to do this using the Devanathan-Stachurski cell, which consists of two cells, one ...
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Single electrode potential measurement

My textbook says that in a galvanic cell, it's not possible to measure single electrode potential independently. Instead, a Standard Hydrogen Electrode is used as the system is under equilibrium. Can ...
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3answers
3k views

How does copper reduce dilute nitric acid to nitric oxide and concentrated nitric acid to nitrogen dioxide?

Here are the 2 equations: \begin{align} \ce{3Cu + 2NO3- + 8H+ &<=> 3Cu^2+ + 2NO + 4H2O} & E &= 0.62~\mathrm{V}\\ \ce{Cu + 2NO3- + 4H+ &<=> Cu^2+ + 2NO2 + 2H2O}& E &...
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1answer
53 views

Electrolytes in electrochemical half cells

In most of the examples in my book I have come across, the electrolyte for an electrochemical half cell has always been the aqueous version of the metal used. For example, a silver electrode is ...
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167 views

Some materials emit more photoelectrons than others - why?

Again, I'm a physicist turning to chemists (so bear with me). So I've been measuring some materials by changing the wavelength of the incident light on the material and I have a detecting tip like in ...
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1answer
42 views

Since a Voltmeter does not account for the internal resistance of a voltaic cell, how can the actual EMF of the cell be measured?

Since a voltaic cell has some internal resistance the voltage measured by the voltmeter connecting the electrodes, is actually lower than the emf of the cell, so how can I measure the EMF of the cell ...

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