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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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A galvanic cell with a salt bridge for demonstration purposes (high school) [duplicate]

I want to design a meaningful galvanic cell experiment for my high school science class. I am tempted to do an experiment without a salt bridge. Why? Because the most common batteries (i.e. lead ...
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24 views

Molar Conductivities of H+ and OH- V/S other Ionic Electrolytes [duplicate]

The following table gives the Ionic Molar Conductivities of a few electrolytes in water. What are the reasons for the unusually high values for both H$^+$ and OH$^-$ even though both undergo solvation ...
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1answer
230 views

Flow of current in graphite [duplicate]

Why current flows through graphite if we join the poles of a battery to it horizontally and why not vertically?
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4k views

Direction of flow of current in electrolytic cell [duplicate]

In an electrolytic cell, does current flow from Anode to Cathode or Cathode to ...
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1answer
263 views

Disproportionation Reaction [closed]

This is the problem I am trying to balance for redox: $$\ce{HXeO4 -> XeO6^{4-} + Xe + O2}$$ It is supposed to be in a basic solution. However, my answer does not contain $\ce{OH-}$ on either side:...
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90 views

Problem in anode in experiment of electrolysis of brass

I am studying the electrolytic determination of copper content in brass (~58% copper, ~40% Zn and other trace elements) by using standard method BS EN 16117-1:2011. Now the electrode used for the ...
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88 views

Why does conductivity of electrolyte solutions peak at high concentrations?

I've recently done a lab about conductivity of brine over time (high concentration salt water). I passed current through salt water and measured the current over time. The graphs I got showed that ...
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1answer
559 views

The similarities and differences between electron transfer and charge transfer [closed]

Please explain the similarities and differences among electron transfer,electron transport, charge transfer, and charge transport from the molecular, atomic and electronic levels. Is electron ...
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16 views

why do we modelize an electronic double layer with a classic capacitor?

in an electronic double layer, there is a voltage drop between the metal and the solution but in the litterature, scientists always modelize EDL with a classic capacitor. My question is why ? because ...
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1answer
276 views

Water electrolysis - what is happening to an iron anode?

So I made an experiment to find a good electrolyte for a water electrolysis. I tried citric acid, which turned out to not produce any gases at the anode, I tried sodium hydroxide, which turned out to ...
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80 views

What actually is electrode potential? [closed]

I was thinking about how Daniell cell works and got into a serious doubt. Let's consider a half cell of Zn. In standard conditions, it'll have an electrode potential of -0.76V with respect to SHE. If ...
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1answer
839 views

Why is the standard reduction potential of an anode negative in a galvanic cell?

It makes not intuitive sense to me why something can have a negative voltage , I understand the concept of voltage drop , but voltage is not being dropped in the anode so why would it be negative ?
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capacitive contribution voltammetry

I am working with a sheet of zinc metal where there is an oxide film on it (ZnO) in passivation conditions (pH=10). I have done voltammetry measurements for different scan rates with a 3 electrodes ...
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1answer
263 views

Removing aluminum oxide before galvanic current and potential measurements

I have an aluminum sample stored about 1 month ago. I am going to couple it for galvanic current and potential measurements. I think the Al sample grew an oxide film due to exposure to air. Would the ...
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22 views

Pseudocapacitive behavior in EC electrode materials [closed]

As we know in electrochemical capacitors or supercapacitors, the basic electrochemical signature is CV (cyclic voltammogram) curve. Some materials like $\ce{RuO2}$ and $\ce{MnO2}$ have a capacitive-...
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1answer
82 views

Coming up with a Mathematical Model to Predict how long a redox reaction can last

The description of my problem is as follows: I will like to find out how can I obtain a mathematical equation which could give me a surface plot of the current output as a function of both ...
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1answer
2k views

Can lead-acid batteries release CO? Or can a CO sensor detect gasses other than CO?

I recently found myself troubleshooting a CO alarm on a houseboat. Inside the cabin, a Fluke CO-220 was reading 40 ppm. In the generator engine compartment, the CO level was zero (while the generator ...
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1answer
205 views

How the Nernst equation is applied for electrodeposition? [closed]

For using the Nernst equation $$E = E_0 - \frac{RT}{nF}\ln\frac{[\ce{Red}]}{[\ce{Ox}]}$$ the concentrations of $\ce{Red}$ and $\ce{Ox}$ species are required. For the reaction $$\ce{Cu+ + e- <=&...
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2answers
176 views

Why does a pickled gherkin glow only at one end when a current is passed through it?

I recently saw this Periodic Video. The Professor (Martin Polyakoff) notes that, The Gherkin normally glows only at one end due to excitation of $\ce{Na+}$ ions. The end which glows can either be ...
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1answer
332 views

What does negative current reading in galvanic couple mean?

I used a multimeter in a galvanic testing between two metals. I connect one to metal A and the another end to metal B. Then I immersed the 2 metals in a salt solution, securing that they are apart in ...
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58 views

Understanding how to choose the right reaction for electrochemistry [closed]

I am quite new here and studying a bit of electrochemistry. In the course of my studies I encountered a problem I couldn't figure out: A sample of iron ore weighing $\pu{0.2792 g}$ was dissolved in ...
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2answers
267 views

Why is hydrogen evolved at the copper side of a lemon battery?

I have 2 quick questions about the principle of a lemon battery. What I understand is that: Zinc is oxidized, freeing up electrons that travel through an external wire to the copper electrode (to ...
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314 views

Measurement of cell constant

Why is cell constant value measured through indirect methods (like using a solution whose conductivity is already known)? Isn't it easier to measure the length and area of cross section of a ...
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2answers
542 views

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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1answer
329 views

Is it possible to improve electrolysis rate without increasing heat?

I'm separating water into hydrogen and oxygen by connecting a DC current to 99.9% pure nickel electrodes in a solution of NaOH in deionized water. It works great, except that any attempts to increase ...
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0answers
21 views

Is flow battery cycle life really as high as the literature claims?

I've seen a few reviews/journal articles now which claim that flow battery cycle life reaches the 10,000 mark and beyond with good capacity retention. However all of the primary sources I've came ...
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1answer
69 views

Which corrodes faster at 5% NaCl solution at room temperature: Steel or Aluminum? [closed]

Which corrodes faster at 5% NaCl solution at room temperature: Steel or Aluminum? Is it true that Al has high corrosion resistance? Or is it just a myth as stated in this article.
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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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31 views

Is there an alternative to potenstiostat in electrochemical measurements?

I want measure electrochemical measurements [potential and current] when 2 different metals are coupled. Is there an alternative equipment to use?
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47 views

Can corrosion from hydrogen peroxide solution model the corrosion protection activities of Al coating?

Immersion in hydrogen peroxide can make steel corrode very fast. However, the coated steel resisted the corrosion attack for a span of time, and as time passes, the coating becomes thinner. Some got ...
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0answers
12 views

Does Aluminum act as a sacrificial anode to steel in saltwater at room temperature? [duplicate]

The steel is coated with aluminum and is immersed at salt water solution. Does the $\ce{Al}$ behave as sacrificial anode?
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80 views

What can explain the more weight gain of aluminum coated steel than non-coated steel after NaCl immersion?

I have a 2 week experiment. I put aluminum coated and non-coated steel of the same size and shape in separate beakers with NaCl solution. Both are sealed. But, I am surprised that Al coated steel ...
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1answer
1k views

Voltage needed for electrolysis of water

Reading the wiki for electrolysis it reads that a potential of 1.23V is needed to separate hydrogen from the oxygen. With that being said, how was that calculated? Does it change with the water volume ...
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1answer
2k views

Difference between Oxidation Potential and Ionization Potential [closed]

Ionization potential indicates a substance's tendency to loose electron and become a positive ion. So, a substance becomes ion more easily if it has a lower ionization potential (lower energy needed ...
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1answer
53 views

Can a reference electrode be inserted into an electrochemical cell horizontally?

If I have an opening on the side of my electrochemical cell, I'm wondering if I can use this to insert a reference electrode. It is normally used to insert an L-shaped tube where you place the ...
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127 views

Standard potentials between a metal and inert electrode

I'm currently in the process of writing a practical report for a chemistry practical I undertook. In short the process was determining the effect of surface area on voltage produced in an ...
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1answer
41 views

Is it possible to have negative corrorion rate and weight loss, meaning specimen [steel] gained weight after immersion in electroyte solution?

Regarding this article, I have read that the corrosion rate and weight loss of a steel specimen after immersion in different corrosive media is negative. I'm surprised that this is really possible. Is ...
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1answer
1k views

Specific conductance of 0.1 M acetic acid

Find specific conductance of $\pu{0.1 M}$ acetic acid given that its molar conductivity is $\pu{4.6 S * cm2 * mol^{-1}}$. I used the formula $\Lambda_m = \kappa/c$, where $\Lambda_m$ is the molar ...
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What is the mechanism that creates a potential between Zn and Cu when they are connected with a wire? [duplicate]

When people explain a galvanic reaction, they usually stop the explanation in the dogma that one is more reactive/electronegative/nobler then the other. But that doesn't really explain the mechanism. ...
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1answer
165 views

What pulls the electrons from iron in rust formation?

In the first step of formation of rust in iron, there is something that pulls electrons from the iron lattice, resulting in the formation of $\ce{Fe^{2+}}$. The reaction is: $\ce{Fe -> Fe^{2+} + ...
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What are the effects of Ag/AgCl electrode liquid interface contamination?

I have been using a $\ce{Ag/AgCl}$ electrode with a porous teflon tip to measure open circuit potential between two electrodes separated by a membrane. I am worried that reagents such as iron chloride ...
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143 views

Does a zinc metal coating react with coffee in a coffee grinder?

I'm restoring an old coffee grinder and I want to give the grinder mechanism a nice zinc / silver coating. But I read it is not safe for zinc to be in contact with acidic foods. When I look at the ...
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1answer
103 views

Is possible to figure out if a battery is NiCd or NiMH?

Aside from opening it of course. I'm not sure if this is the right place to ask this but I have a rechargeable battery pack for an Xbox One controller and the info on it says that it's a sealed nickel ...
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2answers
134 views

Partial reactions in redox formation of rust

In the iron oxidation that results in rust, the first step is to steal 2 electrons from $\ce{Fe}$. The main thief is said to be the oxygen dissolved in water, witch uses the stolen electrons to form $\...
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0answers
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Thought Experiment: Is it possible to preserve the charge imbalance present during molten lead(II) bromide electrolysis?

Suppose I were to electrolyse some molten lead(II) bromide. According to what I have been taught, the lead ions travel towards the cathode and are reduced at it, while the bromide ions are oxidised at ...
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104 views

Aluminium etching

I'm trying to etch a very fine pitch ($\pu{0.5 mm}$) aluminium stencil for use with SMT printed circuit board making. I've done some reading on the topic and found that the safest way probably is to ...
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2answers
3k views

Why do positive ions go to the cathode?

In electrolysis why do positive ions go to the cathode? Since the cathode is positive, won't the positive ions face repulsion at the cathode and would require more energy? I understand that reduction ...
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1answer
803 views

Gibbs free energy and electrical potential

The relation between the Gibbs free energy and the electrical potential is: $$\Delta G=-zFE$$ $z$ is the valence of the electrochemical reaction and $F$ is the Faraday constant. If at equilibrium ...
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1answer
54 views

Why is Cl2 only formed in acidic media?

If aqueous $\ce{NaCl}$ and $\ce{NaClO}$ are added together no reaction occurs, but if you add dilute acid to the solution $\ce{Cl2}$ gas is formed. Why does this reaction only happen in acidic media? ...
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2answers
260 views

In a single cell battery, is voltage exactly equal to cell potential?

I've been researching electrochemical cells. In chemistry-focused sources, you usually see the potential difference between the electrodes referred to as cell potential, but in engineering/industrial ...