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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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Why do electrocatalysts based on polyoxometalates and carbon materials have a weaker activity/performance in acidic media?

I am testing now some doped N and S doped carbon nanomaterials alone and immobilized in POM for the purpose of developing a nanocomposite that can serve as an electrocatalyst for energy-related ...
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Does reduction/ oxidation take place separately at a half cell electrode?

In the redox reaction chapter, we learn that oxidation and reduction go hand in hand. The oxidising agent oxidises by accepting the electron released by the reducing agent and gets reduced in the ...
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Pourbaix diagram and the order of the species

Figure 1. Pourbaix diagram of iron (Source) The line between $\ce{Fe}$ and $\ce{Fe^2+}$ is there because the potential $\ce{Fe/Fe^2+}$ is $\pu{-0.44 V}$. The same applies for $\ce{Fe^2+/Fe^3+}$ with $...
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Can static electricity damage solar cells?

How does static electricity damage common solar cells making them less photo reactive? At watt voltage and/or amps would change the chemistry of the common solar cell? I want to think that as long ...
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What defines a discharged battery?

In the case of an AA Alkaline battery, what actually happens inside the battery once it is fully discharged? What components of the battery change as we use it?
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178 views

Electrolysis of water: Which equations to use? (IB Chem)

There is a list of standard electrode potentials at 298 K from the p. 23 of IB Data Booklet 2016. Which of the following equations (forward/backward reactions), from the two possible ones involving ...
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Charge phone using simple voltaic cell [on hold]

Can i charge my phone using voltaic.cell and. How because i have cut the usb wire and found 4 wire in it which is red,black,green,white which one is connected to mg and which one is connect to copper
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Where does copper form?

I thought zn and cu both lose 2e- to pt but someone is telling me it's wrong]
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90 views

Determining the reduction potential of a half cell reaction at a given pH

$E^\circ_\ce{Cu^2+|Cu} = \pu{0.34 V}$. What will be reduction potential at $\mathrm{pH} = 14$ for the same couple? Given that $K_\mathrm{sp}$ of $\ce{Cu(OH)2}$ is $10^{-19}$. My Attempt I think ...
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199 views

Can gas be made to block radiation better?

Can any gas block radiation? I ask this because I would like to know if the properties of any gas element would chemically react differently with radiation from adding an electrical current. This ...
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Why is reduction potential of water ( 2H₂O + 2e⁻ → H₂ + 2OH⁻ ) is -0.83 insted of 0, as in the case of (2H⁺ → H₂)?

I came across this value of reduction potential of water while solving a question. Also, I noticed that, for example $$\ce{Ag+ → Ag}$$ has a fixed standard potential, and the same is used when we do ...
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Which is anode and which is cathode?

A maybe (hopefully) simple question about the denotations of "anode" and "cathode". The below image is a schematic of a polymer solar cell (Source (WBM)). (The figure text is quoted as well for the ...
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107 views

Confusion about the relation between gibbs free energy and electromotive force

$$\Delta G = -nFE$$ My textbook says that we can measure that this $\Delta G$ is measured when the work is done reversibly. But my confusion is how will we work reversibly when we have an ...
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1answer
129 views

Does Intercalation and Deintercalation of Lithium ions occurs in Half Cell?

The important feature of Lithium ion batteries is the ability to intercalate and deintercalate lithium ions in anode and cathode . However when we use half cell, using lithium metal foil as anode, ...
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Formula Issue: At what relative concentrations of Pb2+ and Cd2+ will these half-reactions have the same reduction potential 25 degrees Celcius? [closed]

Standard reduction potentials for the Pb2+/Pb and Cd2+/Cd half-reactions are −0.13V and −0.40V, respectively. This is the question, I’m just confused on which formula should be used. E=E^0-(0.0592V/n) ...
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115 views

what should be the onset potential using cyclic voltammetry?

I am working for PEM fuel cell cathode material. I am confused regarding the onset potential determination for my catalyst (CV attached, fig 1 is complete CV while fig 2 is its zoom image for clear ...
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1answer
186 views

Why is the conjugate of a strong oxidizing agent a weak reducing agent?

I am a grade 12 student. While I was reviewing some electrochemistry, I had the following question. Take this reduction half-reaction: $$\ce{F2 (g) + 2e- <=> 2F- (aq) + $\pu{2.87V}$}$$ I know ...
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Which half cell equation do you switch when calculating E° cell?

Given the following standard potentials calculate the overall $E^\circ_\mathrm{cell}$: $$ \begin{align} \ce{Pb(SO4)(s) + 2 e- &→ Pb(s) +SO4^2-(aq)} &\quad E^\circ &= \pu{-0.356 V} \\ ...
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50 views

Current in a Lithium Ion Battery

I am trying to find the current transferred to the anode and cathode of a Lithium Ion Battery at different voltages. I know the temperature (approximately) of the battery, the battery's starting ...
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1answer
93 views

Unknown salt formed from electrolysis of urine

I am not sure what I was expecting to happen with this but I created a circuit to electrolyze various household liquids. My electrodes are copper — or at least claim to be, I think they might just be ...
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2answers
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Oxidation of metals/halogens by oxygen gas in acidic aqueous solution

I had some confusion about the correct answer to the following question: Which substance can be oxidized by $\ce{O2(g)}$ in acidic aqueous solution? Two of the answer choices were metal cations (...
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Why is the reaction between potassium permanganate and hydrogen peroxide spontaneous?

When hydrogen peroxide is mixed with potassium permanganate, oxygen gas and water vapour are formed, according to the reaction (source): $$\ce{2MnO4- + 3H2O2 -> 2MnO2 + 2H2O + 3O2 + 2OH-}$$ This ...
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Still taught to reverse oxidation half cells in electrochemistry?

In a question, Oxidation of metals/halogens by oxygen gas in acidic aqueous solution, there was a point made that reduction half-cells should not be reversed. I was taught ($\approx 1970$) in the ...
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What is the ideal temperature and pressure to crack water?

Using sun mirrors and solar cells for electricity. What temperature, pressure and voltage ideal for cracking water. Source: NPR Source Would it take more or less electricity to crack water under ...
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Metal that does not deposit silver (Ag)

Hi Chemistry enthusiasts! I am working on my scholarship exam practice but I am considered myself as a newbie so I would like to hear your opinion :) From (1)-(4) below choose the metal that does ...
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Is it possible to generate electricity by using two inert electrodes in a galvanic cell?

The Daniell cell has two active electrodes, meaning that both the copper and the zink electrodes participate in the redox reaction. However, in a lemon battery for example, the copper electrode is ...
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1answer
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Electrolytic cell to remove soft solder from silver?

Hi my chemistry is pretty dire but have vague idea that an electrochemical cell could be used to remove soft solder (lead/tin probably) from a piece of sterling silver in need of a repair. The ...
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1answer
71 views

Pale blue species forming during electrolysis of NaHCO3

I have a solution of 3500 ml $\ce{H2O}$ + 454 g $\ce{NaHCO3}$ in electrolysis at a potential of 12.5V using a lead anode and copper cathode. The surface areas aren't measured but they are enormous. I ...
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25 views

Calculate chemical potentials to find electrode Fermi level

I'm running some simple simulations of the semiconductor-electrolyte interface and I'm having a hard time figuring out the equilibrium condition. Can someone please help me with my electrochemical ...
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2answers
320 views

Using a calcium metal anode in aqueous solution?

In school, I am doing an electrochemistry lab in which I need to create a galvanic cell battery with the highest voltage possible using two beakers, a salt bridge, and electrodes. To maximize the ...
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What is the flow of electrons, cations, and anions in a voltaic cell (please see image attached)?

This is an IB question. The mark scheme says that the correct answer is A and only A. But I believe B is also correct. The following is my thought process. Since A is more reactive, it undergoes ...
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For Hess' law type questions, when do you take the inverse of the constant and when do you switch the sign?

For example, when you're given the enthalpy $\Delta H$ of a reaction and you want to switch that reaction around in order to add it to something else, you switch the sign. Furthermore, when adding ...
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What is the difference between molar conductance and molar conductivity?

I'm learning (or at least trying to learn) about electrochemistry, but a major obstacle to that, is that different books I refer use different terms for the same symbols. So in a last ditch attempt to ...
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Would electrolysis work with a conductive (but waterproof) divider between anode and cathode?

Note I am not trying to "double fuel efficiency" in a car or something scamey like that. My purpose is to fill balloons with hydrogen and possibly power an HHO torch (also make it safer because pure ...
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1answer
29 views

[Co(H2O)6]3+ vs [Co(NH3)6]3+ oxidising water

Cobalt(III) complexes cannot be prepared by addition of the ligand to a solution of the metal cation because the aqua cation $\ce{[Co(H2O)6]^3+}$ has no stable existence in solution. It is strongly ...
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What do electrons usually do when lead acid battery is idle?

Lead acid batteries operation are governed by Redox reactions for charging and discharging. But, what do electrons usually do when lead acid battery is idle? And why? Assumptions: Say more ...
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Reduction Potentials [closed]

Standard electrode potential values can be used to judge the reducing ability of a metal. When I was introduced to this topic a simple picture was painted: you put a metal into a solution of its ions. ...
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8k views

Express the maximum work from a voltaic cell

The net cell reaction of an electrochemical cell and its standard potential is given below: $$\ce{ Mg + 2Ag+ ->Mg^{2+} + 2Ag} \ \ \ \ \ \ \ \ E^\circ=3.17\:\mathrm{V}$$ The question is to find the ...
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Confusion on electrode potentials

Standard electrode potential values can be used to judge the reducing ability of a metal. When I was introduced to this topic a simple picture was painted: you put a metal into a solution of its ions. ...
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1answer
64 views

When surface area of electrodes is increased, why does the current in the galvanic cell increase?

I did a lab in galvanic cells where I changed the surface area. As a result, the current increased, but I don't really understand why. I guessed it was because more are means that more ions from the ...
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1answer
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What are the products in the reaction of sulphuric acid and Group 2 metals?

When group 2 metals, says magnesium, is reacted with nitric acid, oxide of nitrogen is produced beside hydrogen gas. The standard electrode potential values agree with this: $$ \begin{align} \ce{Mg^...
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What is the reasoning behind deriving electrode potential of a metal-metal sparingly soluble salt electrode?

Considering a sparingly soluble salt $M_xN_y$ of the metal $M$, in which the corresponding reaction is $M_xN_y$ = $xM^{y+}$ + $yN^{x-}$, the standard electrode potential is given by $E^{o}_{M_xN_y/M/...
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1answer
699 views

Nernst equation for a fuel cell when gases are stored separately

I have run some tests with a PEM fuel cell and the voltage we have found was $1.44\ \mathrm{V}$. Given that the standard potential for a fuel cell is $1.229\ \mathrm{V}$ what is causing the difference ...
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Does increasing the concentration of the anode electrolyte in a galvanic cell increase or decrease the voltage produced

Im in kind of a pickle here. I am using nernst equations to calculate the theoretical voltage produced for different concentrations of $\ce{Al(NO3)3}$. Reaction: $$\ce{2Al(s) + 3Pb^{2+}(aq)⟶2Al^{3+}(...
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How does a Pt and reference electrode measure the cell potential in a potentiometric titration?

I'm trying to perform a potentiometric titration to determine the redox potential of a $\ce{Fe^3+|Fe^2+}$ couple. To do this, I am using an $\ce{Ag|AgCl}$ electrode connected to an inert $\ce{Pt}$ ...
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1answer
32 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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1answer
166 views

Does higher Oxidation/ reduction potential translate to higher energy storage in battery?

Some articles refer to the fact that Lithium is preferred metal of choice for batteries because their half cell voltage is high (slightly above 3V) If that is the case why can't we use other metals ...
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What are the reasons that make platinum a good electrocatalyst for oxygen reduction reaction? [duplicate]

Researchers are trying to find new electrocatalysts for energy related reactions in fuel cells in order to replace the expensive platinum-based materials. I would like to know what are exactly the ...
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2answers
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Where does Free Energy go in a Redox Reaction?

This doubt came to my mind while answering the following question: Why does a voltaic cell not operate unless the two separate compartments are connected by an external circuit? The answer seems ...
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3answers
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No sign flipping while figuring out the emf of voltaic cell?

I learnt that for a voltaic cell, the value for the $E_\text{cell}^\circ$ when the reaction is spontaneous is given by $$E_\text{cell}^\circ = E_\text{cathode}^\circ - E_\text{anode}^\circ, \label{...