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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4
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1answer
86 views

In a battery, what happens to LiCoO2 when the lithium leaves? It becomes CoO2?

What chemical compound exists at the cathode of a lithium-ion battery when the lithium is not there? The cathode is usually described as $\ce{LiCoO2}$, so does it become $\ce{CoO2}$? $\ce{CoO2}$ ...
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3answers
2k views

How does electrolytic conduction depends on the size of ions & their solvation?

The textbook says, The smaller the effective size of the ion after solvation, the greater will be its conducting power." But, on the Internet, it is explained as follows: Radius decreases, ...
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1answer
114 views

Nernst equation and equilibrium

I am currently stuyding electrochemistry, and recently I've stumbled upon a problem where one is supposed to calculate the concentration of Fe3+ ions after a solution containing Fe2+ was titrated ...
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0answers
36 views

How can I calculate the diffusion limiting current density?

I know the concentration of a substrate in a water solution and I want to calculate the diffusion limiting current density for an electrode that reacts with that substrate. What are the steps to ...
2
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1answer
77 views

What is the number of electrons being transferred in electrolysis of aluminum oxide? [closed]

$$\ce{ 2/3 Al2O3 -> 4/3 Al +O2}$$ As we know, to find the Gibbs free energy, we need to use this formula: $$ G= -nFE^\circ$$ What would $n$ be in this case? After breaking it down into the half ...
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1answer
39 views

Why the electrolyte is made up of the same metal which is being electro refined? [closed]

For example for the electrorefining of Cu the electrolyte is CuSO4... WHY the salt of the same metal is used as an ELECTROLYTE..??
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2answers
54 views

Why we do not add salt water to the batteries instead of acid? [closed]

Actually I was just thinking that since we add acid to the batteries to increase the conductivity but the thought simply crossed my mind that salt are strong electrolytes so there should be a good ...
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2answers
212 views

How do ions conduct electricity? [closed]

I mean to ask what do ions actually do while conducting electricity? Do they simply take up the electrons and transport it? If it is so, I do not understand how anions can take up more electrons if ...
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1answer
423 views

Does standard electrode potential depend upon temperature?

Does standard reduction potential depend on temperature? I am confused because my institute gives the definition for standard reduction potential as the potential that is measured at standard state ...
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3answers
147 views

Current with an ionic solution [closed]

For the last assignment of the school year, my science teacher gave the class questions about chem, physics, etc. The third question had me confused and I'll be thankful for all the help given. The ...
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1answer
59 views

Are electrostatic effects temperature dependent? [closed]

A charged particle like an ion, does its repulsive or attractive effect on other particles change with temperature? Are electrostatic effects temperature dependent?
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1answer
49 views

Role of potassium hydroxide in alkaline battery?

Is the role of potassium hydroxide ($\ce{KOH}$) in an alkaline battery to provide hydroxide for the reaction with zinc? Would the battery cease to work if $\ce{KOH}$ was removed and only $\ce{OH-}$ ...
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2answers
190 views

In a galvanic cell, why do electrons move through the wire from zinc to copper?

I understand that there is aqueous $\ce{Cu^2+}$ in this scenario which pulls on the electrons from the zinc causing the electrons to move through the wire, but how does the electronegativity of $\ce{...
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0answers
28 views

Why isn't the chemistry of a zinc-air battery (meaningfully) hindered by an activation energy barrier?

Virtually every source I've read pertaining to zinc-air batteries explain the chemistry of it either using these formulae or a simplified version of them: $$ \begin{align} &\text{Anode:} &\...
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0answers
37 views

Reduction potential for reduction of O2 to H2O2 in alkaline medium

I've read that $\ce{H2O2}$ is a good reducing agent in alkaline medium and can reduce $\ce{Fe^3+}$ ions to $\ce{Fe^2+}$ in alkaline conditions. But I need to verify this using the standard reduction ...
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1answer
98 views

How does the charge imbalance affect the cell reaction when there is no salt bridge in a galvanic cell?

As mentioned in the answers to this question Why is it important to use a salt bridge in a voltaic cell? Can a wire be used? a salt bridge is used to keep the two half cells neutral. i understand how ...
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3answers
2k views

Do We change sign of electrode potential when reversing an equation?

I have a cell equation as: $$\ce{2Cr^0 + 3Cd^2+ -> 2Cr^3+ + 3Cd^0}$$ I am provided the standard reduction potentials as: $$\begin{align}\ce{Cd^2+ + 2e- &-> Cd} && E= \pu{-0.4V}\...
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1answer
134 views

Rusting of iron is quicker in saline water than in ordinary water [duplicate]

I feel so because, saline water has more more electrons and because of that there will be oxidation will take place faster and hence the overall process will speed up. Is this explanation good enough ...
3
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1answer
395 views

How to find the potential of a mixed Iron/ Cer solution?

Given the following half-reactions: \begin{align} \ce{Ce^{4+} + e^{−} &-> Ce^{3+}} & E° &= \pu{1.72 V}\\ \ce{Fe^{3+} + e^{−} &-> Fe^{2+}} & E° &= \pu{0.771 V}\\...
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0answers
65 views

What happens to a flat lemon and can it be recharged? [closed]

A lemon can be used as a battery, and is often used to teach kids the basics about electricity and chemistry. This is due to their acidic and electrolytic properties. What happens to a lemon when it ...
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0answers
50 views

Aluminum Hydroxide electrolysis

Does molten Aluminum Hydroxide break up to aluminum, water, and oxygen by electrolysis? It's easy to write the equation $$\ce{4Al(OH)3 -> 4Al + 6H2O + O2}$$ but is this actually possible?
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2answers
15k views

Derivation of relationship between Gibbs free energy and electrochemical cell potential

Why is $\Delta G = -nFE$? I don't understand what the motivation is behind this definition. Was it derived or just given? The textbook provides no justification for this equation. In fact, much of ...
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1answer
95 views

Calculation of the cell potential of a lemon battery experiment

I have the following problem that I would like to get checked. I’m told to calculate the cell potential of a simple lemon battery experiment. After Finding out the oxidizing agents and the reducing ...
5
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1answer
339 views

Electrolytic Refining of Silver Nitrate

I read that the electrolytic refining of Silver is done using dilute silver nitrate as an electrolyte and a small percentage of free $\ce{HNO3}$. The following reactions are possible at the anode: $$\...
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1answer
71 views

How does electrolytic conductance depend on solvation?

My textbook says: If the ions are strongly solvated their effective size will increase and hence their conductance will decrease P.s after reading my textbook, I don't think I'm sure what solvation ...
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0answers
68 views

Why is E°(cell) not ∆E°cell?

$E^\circ_\mathrm{cell}$ is the EMF of the cell for a reaction with respect to standard hydrogen electrode (SHE). So why don't we represent $E^\circ_\mathrm{cell}$ or $E_\mathrm{cell}$ by $\Delta$ ...
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1answer
129 views

Calculating the biological standard potential

I have an electrochemical cell with following overall reaction: $$\ce{5 Sn^4+ + 2 Mn^2+ + 8 H2O <=> 5 Sn^2+ + 2 MnO4- + 16 H+}$$ I have defined the half reactions as: $$ \begin{align} \ce{Sn^...
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1answer
179 views

What is the state of aggregation of iodine formed during electrolysis of molten nickel(II) iodide? [closed]

Assume the electrolysis of molten $\ce{NiI2(l)}$ (inert electrodes) in a cell. The cell with a heating element is in the room; the room is at $\pu{25 °C}$ and $\pu{101.3 kPa}.$ The half-reaction for ...
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2answers
69 views

What are possible anode materials for copper(II) sulfate electrolysis?

I'm a student doing a research paper about copper sulfate electrolysis with an experiment by varying anode material, and aside from Pb and graphite (and pure Ti which I think wouldn't work without ...
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0answers
33 views

Problem interpreting CV diagram in a paper

I am an undergraduate materials science student. I am currently preparing to conduct some research over the summer on alkaline electrolyte membrane fuel cells and have been reading some papers to get ...
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1answer
94 views

Why is it necessary to bubble hydrogen through the electrolyte in a hydrogen electrode? [closed]

I searched from the internet but i got confused. I was not sure about my answer.
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1answer
42 views

Where do the electrons in lead–acid battery come from? [closed]

$$ \begin{align} \ce{PbO2 + H2SO4 &-> PbSO4 + H2O + O} &\quad &\text{(anode)}\\ \ce{Pb + H2SO4 &-> PbSO4 + H2} &\quad &\text{(cathode)} \end{align} $$ The cathode’s $\ce{...
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0answers
19 views

Nernst equation for mixed cathode battery

What is the Nernst equation for a mixed cathode battery or a cell where there are multiple half reactions? I assume it is similar to unequal voltage connected in parallel? https://youtu.be/XoLzn49IZjM ...
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1answer
45 views

Contradiction in variation of conductance and conductivity on dilution

I do conceptually understand that on dilution conductivity decreases and conductance increases but if we look at the formula of conductivity, a contradiction seems to arise. $$\kappa=GG^*$$ where $\...
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0answers
27 views

Mass Transport and Ion Transport - Li-ion Batteries

I am new to the field and trying to grasp the theories/ physical phenomena behind the Li-ion batteries. I came across two phenomenons 'Mass transport' and 'Ion transport'. As I understood Mass ...
3
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3answers
242 views

Copper electrode in a Daniel cell

Suppose I have a beaker containing $\ce{CuSO4}$ solution and I dip $\ce{Cu}$ rod in it. What reactions are going to take place? Is the $\ce{Cu}$ rod going to acquire any positive charge? I am asking ...
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1answer
51 views

Why can't two 3° free radicals combine?

In Kolbe Electrolysis, my teacher told that when a 1° or 2° free radical is used, we get alkanes through dimerisation. Why wont dimerisation occur for a 3° one??
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0answers
99 views

Effect of charge density on electrolysis of dilute sulphuric acid

I am told that if electrolysis of dilute sulfuric acid is performed under high charge density, then the following reaction takes place at anode instead of evolving oxygen: $$\ce{2 HSO4- -> H2S2O8 +...
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1answer
211 views

Why does molar conductivity depend on the volume of the solution? [closed]

I have been searching the answer to this question everywhere and (almost) the only answer I get is to formula based: ‘Since molar conductivity = k / M = k/1/V for one mole = kV Therefore molar ...
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0answers
69 views

Did both temperature of nernst equation same

I saw the nernst equation I have a doubt.Did the temparature at which Standard potential is measured is also the temparature at which electrode potential is measured. I mean Did the temperature (T) in ...
2
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3answers
65 views

Trying to understand the chemistry in an iron carbon battery

I am trying to understand the chemistry that occurs in an iron carbon battery during charging. The negative electrode is iron, the positive electrode is carbon. The electrolyte is iron(II) chloride. ...
1
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1answer
583 views

What is the meaning of signs in electrode potentials?

Question Suppose you have a cell set up between a copper metal/copper(II) ion electrode and a reference electrode. Under standard conditions, the emf of this cell was −0.07 V. The standard electrode ...
2
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1answer
4k views

What is the electrical conductivity of pool water?

What is the electrical conductivity of pool water? I tried to find some information, unfortunately without success. I need to know it to make an underwater electronic project.
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1answer
24k views

Salt concentration and electrical permittivity of water

We know that the electric flux density $D$ can be related to electric field intensity $E$ as $$D = \epsilon(\omega) E$$ where $$\epsilon(\omega) = \epsilon_0 \epsilon_r(\omega)$$ and $\epsilon_0$ ...
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2answers
1k views

Does Copper reacts with Sodium Sulfate solution?

Okay I am trying to make a capacitor in which current collector is copper foil and electrolyte is sodium sulfate. Would this work? Do these two react with each other or not?
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4answers
272 views

What happens when a piece of copper is placed in 1M HCl?

I know that the answer is that nothing happens, but the explanation is confusing me in some places. Firstly, we are given that: \begin{align} \ce{Cl2 + 2e- &-> 2Cl-} & (E &= \pu{1.36 V})...
4
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1answer
115 views

Why is the concentration halved at the intersection of Hg²⁺/Hg₂²⁺?

For the couple $\ce{Hg^2+}/\ce{Hg2^2+}$: $E^\circ = \pu{0.91V}$. At the border the concentration is $c = \pu{0.10 mol \cdot L-1}$ for all ions. Hence build the stability diagram of mercury. I have: ...
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1answer
72 views

What is the substance turning salty water green when electrolysed? [duplicate]

I am a student and I take O.L. Chemistry, in my knowledge I know if I electrolysed concentrated aqueous NaCl solution I should get Hydrogen evolved at the cathode and chlorine at the anode. I did an ...
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1answer
204 views

why does galvanic cell stop working when charge neutrality is not maintained? [closed]

In galvanic cell, salt bridge maintains charge balance between solutions. If there's no salt bridge, charge neutrality will be broken as solution(anode) becomes positive and that of cathode becomes ...
1
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1answer
152 views

Would a salt bridge work through which the ions could not diffuse into the half cells?

Instead of covering the ends of the salt bridge in an electrochemical cell with a membrane, one could also plug them on both sides with a conductive non-porous material, for example gold, which doesn'...

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