# 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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### Why does the application of external mechanical pressure increase the performance of lithium-ion batteries?

Many electric vehicle batteries - specifically lithium-ion ones considered for this query - can be subjected to external mechanical pressure because it increases battery performance. What components ...
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### Which is more efficient way to generate energy using hydrogen: direct hydrogen combustion or through fuel cell? [closed]

Which is more efficient way to generate energy using hydrogen: direct hydrogen combustion or through fuel cell? Please explain so that even a primary school student can understand.
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### What is 'absorbance power' in electrochemistry?

I have been asked $\ce{250 mL}$ solution of unknown molarity of $\ce{CuSO4}$ in water was electrolysed using platinum electrodes. After the passage of a current $2 \times 10^{-3}$ ampere for $19.3$ ...
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### Why do we need salt bridge in a cell during potentiometric measurement as there is no or minimum redox activity at electrodes?

In electrochemical cell, we need salt bridge to maintain electrical neutrility in both halves cells during redox reaction?. But in during potentiometric measurement, no or minimum current is drawn and ...
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### what does Area(A) in Randles-sevcik equation refer to? geometrical area of electrode or electrochemical active surface area/

In the Randles-Sevcik equation, $$i_p = 0.4463 \ nFAC \left(\frac{nFvD}{RT}\right)^{\frac{1}{2}}$$ we have an area $A$ in the formula. is this the electrochemically active area or geometrical area? ...
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### Van Der Waals Interactions [closed]

The radius of one sphere is 5 nm, and another sphere is 10 nm. Determine the van der Waals interaction for the following conditions: a) Distance between the spheres is 20 nm and the hamaker constant ...
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### Water electrolysis [closed]

What happens when the power source is cut off from the electrodes? Do the electrons that travelled from the anode to cathode return back to the anode? Are the electrodes re-usable?
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### Reduction Potential of Fe[(C2O4)3]3- /Fe2+

I need the standard reduction potential of the couple $\ce{[Fe(C2O4)3]^3-}$ / $\ce{Fe^2+}$ . I searched for it in many reduction potential tables on the web in vain. If someone can tell me where to ...
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### How can the difference between surface energy and electrostatic repulsion be calculated in electroplating?

When metals are electroplated unto surfaces, there are a myriad of forces at play. To set a clear example, if one were to electroplate a magnet with a diamagnetic metal such as bismuth, there will be ...
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### Electrodes selection in electrolytic cell [closed]

In electroplating, why is metal to be electroplated connected to positive terminal of the battery only????
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### Entropy change during electrolysis of water

Consider the electrolysis of water reaction: $$\ce{H_2O -> H_2 + 1/2O_2}$$ At room temperature and atmospheric pressure, the change in enthalpy of this reaction is $\Delta H = \pu{+286 kJ mol-1}$. ...
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### Considering Gibbs energy or electrode potential to find disproportionation tendency

The following data was given (without the asterisks and footnote) asking us to find the oxidation states that would have a tendency to disproportionate - By tendency to disproportionate, I understood ...
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### Conductance and concentration of a strong electrolyte

I learnt that with the increase of concentration, conductance of tr electrolyte decreases. While looking for the reason I found in my textbook that if concentration increase, amount of ions increases ...
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### Electrochemical etching of silicon

I am doing some research on porous silicon in electrochemical biosensors. I have come across the electrochemical etching method to produce porous silicon for the biosensors. I have also come across ...
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### Thickness of proton exchange membrane (Nafion)?

I am looking into using a proton exchange membrane for a bio-energy cell experiment. Previous scholars have been using Nafion as a PEM to place between the anode and cathode (air-cathode). the ...
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### Cathodic protection

My doubt is regarding cathodic protection. I have understood protection of metal by using sacrificial anodes as its a clear example of an electrochemical cell. However, in ICCP we make a less reactive ...
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### In a perfect electrolytic cell, would the anode and cathode change by the same amount

If I had a theoretically perfect electrolytic cell, such as one with Copper anodes and cathodes, and a copper nitrate solution, over a given time period with a voltage applied, would the change in ...
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### Potential difference between metallic electrodes in water

If I dip two pieces of metal in tap water I measure a potential difference between the two electrodes with a common digital voltmeter. For example, for Cu and Al I measured 0.55 V and for Cu and Fe I ...
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### What are the half-cell redox reactions of water in different pH solutions?

While reading about the electrolysis of aqueous sodium chloride solution, I realized that the half-cell reactions depend on the pH of the solution. According to my understanding, the following ...
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### Why are conductance and conductivity additive in nature? [closed]

In my book, it is written that: $κ_{electrolytic solution} = κ_{electrolyte} + κ_{solvent}$ $G_{electrolytic solution} = G_{electrolyte} + G_{solvent}$ Where $κ$ and $G$ are conductivity and ...
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### What are the similarities / differences between the terms anode / cathode and oxidizing agent / reducing agent? [closed]

I'm kind of confused on how to distinguish the terms anode and cathode from oxidizer and reducer or oxidizing agent and reducing agent. Some references prefer to use one over the other in discussions ...
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### Why Does Electrical Work Cause Changes in Internal Energy of the System? [closed]

If we look at system at constant temperature and volume which is galvanic cell, first law of thermodynamics states: $$dU = dQ + dW'$$ Where W' is electrical work exchanged with surroundings and Q is ...
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### What Does Electrical Work Represent in Context of Electrochemical Cells?

If cell operates reversibly than change in Gibbs energy of system equals electrical work of the cell. As far as I know electrical work is work done by electric field when charge moves between certain ...
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### Can you create a temporary bond in between an atom and a filter by electrically charging the filter?

I want to be able to turn a filter on and off by electrically charging the filter so that it creates a temporary bond that blocks up the filter then, by discharging the filter, releasing the temporary ...
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### Enthalpy of Reaction and Efficiency of Electrochemical Energy Devices

For electrochemical energy devices such as batteries or fuel cells working reversibly, efficiency is defined as: $$\eta = \frac {\Delta_rG^⦵} {\Delta_rH^⦵}$$ Since cell operates reversibly Gibbs ...
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### Calculating the value of equilibrium constant using cell potential differences

Calculate $\Delta G^\circ$ and $K$ at $\pu{25 ^\circ C}$ for the following reactions. (a) \begin{align} \ce{Cu^2+ + 2e- &-> Cu}\quad E^\circ = \pu{0.34 V} \\ \ce{Fe^3+ + e- &-> Fe^2+}\...
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### Grotthuss mechanism and diffusion of hydroxyl ions

Does a new water molecule form and result in a new hydroxide being formed?
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### How does the membrane potential change so drastically during an action potential?

I understand that the Nernst potentials $$V = \frac{k_\mathrm{B}T}{e} \ln\left(\frac{c_\mathrm{out}}{c_\mathrm{in}}\right)$$ for all ions inside and outside a cell barely change when an action ...
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### What is a suitable material for a cathode in electroplating experiment?

I am going to do an electroplating experiment, whereby I will be using a Cu(NO3)2 solution to plate onto a cathode. What is an easily accessible cathode which I can use for this? Would a strip of Ag (...
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### How is it possible to electroplate using an Al3+ solution, when water is a stronger oxidant?

Suppose that I wanted to electroplate Al(s) onto a Cu(s) Cathode, (using an Aluminium Nitrate solution and Al(s) anode). At standard conditions, Al(s) is the strongest reducing agent, which is good. ...
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### Why do galvanic cells need a salt bridge while electrolytic cells don't?

I see the questions of why a galvanic cell needs a salt bridge and why a electrolytic cell doesn't need a salt bridge being answered separately but I still can't grasp why you are not allowed to mix ...
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### Need help to calculate results of an electrochemistry cell potential lab work

So, the lab work is this. I made an AgCl electrode of a silver wire by coating it with AgCl. This was done by electrolysis by immersing the wire in HCl and using platinum as a counter electrode and ...
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### What determines the product at the anode/cathode of a electrolytic cell with an aqueous solution?

If you perform electrolysis on Aqueous Sodium Chloride of various concentrations, how does the product at the anode change but the product at the cathode does not? What is the mechanism behind this ...
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Hello, I will list the questions directly, if you want to know details please read below. As in the figure, we have water+baking soda in a plastic cup, there are 2 versions in figure that affects LED'...
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### How are ions transported in solid state electrolytes?

Consider an inorganic solid state electrolyte in a solid state Li-on battery. It being solid means that the atoms or ions that make up the solid itself are not mobile. Then how do the ions move ...
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### Effect of side reactions on galvanic cell using iron rod as anode and sodium chloride as salt bridge

We just made a galvanic cell on a chemistry lesson using iron, iron sulfate , copper and copper sulfate. We used a sponge soaked in $\ce{NaCl}$ solution as the salt bridge. The issue is that we ...
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### What an electrolyte “really” does in electrolysis?

I am reading about electrolysis and I have trouble to understand why an electrolyte must be added in order for electrolysis to occur. I have read this question but still can't get it. The definition ...
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### How to write the Nernst Equation for this reaction?

I am required to write the Nernst equation for the following reaction: $\ce{O_2 + 4H^+ + 4e^- -> 2H_2O}$ Clearly, here $\ce{O_2}$ is getting reduced from an oxidation number of zero to an ...
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### What is the typical resistance of a piece of 1 cm^2 of carbon paper?

I have been using carbon paper (Carbon sheet 99.8% from STERM CHEMICALS) to load catalysts for fuel cell study. Just now, I realized that for a 1 cm^2 piece the resistance is about 3 ohms! Is that a ...
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### What is the reason for decomposition of layered cathode materials?

Articles like this claim oxygen can evolve from layered metal oxide cathode materials when charging the Li-ion battery. Is it the high positive potential given to the cathode while charging pulling ...
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### Entropy Changes in Electrolytic/Galvanic Cell?

One of the most fundamental equations in chemical thermodynamics states: $$\Delta_rH_m^⦵ = \Delta_rG_m^⦵ + T\Delta_rS_m^⦵$$ If we look at this equation in context of net chemical reaction in ...
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### Why does a potential on the reference electrode create an offset on the measure electrode of a pH probe? [closed]

I am making an analog front end for a pH probe and i encountered a design where creating an offset on the reference electrode, creates an offset on the measure electrode. How does that work ? Does the ...
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### is electrolysis of water less efficient with warm water? E.g 40, 50, 60… °C

I see there is High-temperature electrolysis which is a whole different animal than room temp electrolysis. I want to know if electrolysis of lukewarm water will behave much differently. My guess is ...
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### What does the horizontal axis on cyclic voltammograms mean?

In cyclic voltammograms (like the one in the attached image) what exactly is the horizontal axis' voltage refering to? Is it the measured voltage between the reference electrode and working electrode? ...
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### Why a Li-ion battery, when in storage, is better kept around 85% instead of 100%?

I discovered that in my laptop settings, I can select an option that is best chosen when the laptop is mainly connected to AC power, and apparently keeps the battery at a lower SOC. I found this ...
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### About the acidity of phenytoin

Can you explain why phenitoin is weak acid even though nitrogen is base? Does carbonyl group always make structure acid? If this structure doesn't have carbonyl group, would it be base not acid?
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### How to melt and roll silver chloride into sheets

I want to make silver chloride cathodes for a magnesium salt water battery. Are there any tips on how to proceed? I hope to melt the silver chloride in a covered ceramic crucible in an electric ...
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### Electrolysis in Electrophoresis of proteins and DNA

Can electrolysis happen in an electrophoresis assay (such as SDS-PAGE)? To perform electrophoresis, the substances must be dissolved in an aquatic buffer with a previously determined ionic strength. ...
I was hoping for some help with choosing half-reactions for an electrolytic cell. This was the problem that sparked the question (Question #6 from the 2020 USNCO Part II): The correct answer is 2\...