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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1answer
19 views

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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60 views

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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combination of H2 and O2 after electrolysis [closed]

if we electrolysis water in a closed container H2 and O2 is formed, now as the container is closed both gases remain there when the electrolysis stop and water cool down will h2 and o2 remain in the ...
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29 views

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's the error in part (b) of this question about a voltaic cell reaction? [closed]

The problem in the image was asked on a GenChem test recently. The work seems fine but the answer doesn't pass the smell test for reasonableness as it seems to be WAY too high. Where's the error? (...
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28 views

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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Can Tin Oxide be used as an anode in electrolysis?

Can Tin Oxide (pure or plated on graphite, etc) be used as an anode in the electrolysis of sulfate salts? like lead oxide Electrodes. I've heard that tin-graphite composites are used in lithium-ion ...
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How are we going to handle oxygen shortage problem arising due to massive usage of current fossil fuel combustion and future Hydrogen fuel cell tech? [closed]

The current corona pandemic has created a situation where in order to save lives, there is a huge huge requirement for clinical oxygen (which is taken from the environment) all over the world. Now, ...
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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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does a reaction happen 1 mole times before cell stops working? [closed]

I have been told delta G=nF*delta E where n moles electron have been have pushed from anode to cathode,and n is the number of electron transfer in one balanced reaction. Does this imply the reaction ...
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What is reduction potential of Au(I)-GSH to make Au25(SG)18 clusters? [closed]

I am tryring to make Au25 glutathione clusters and was wondering what is the reduction potential for Au(I)-GSH to make Au(0) in clusters Au25(SG)18.
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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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Metal-Metal Insoluble Salt Electrode

How to derive the relation between the standard electrode potential of a metal-metal ion electrode and a metal metal-insoluble salt electrode? (Where the ion is a general ion with valency $n$, and the ...
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concentration affect on cell potential

I conducted a galvanic cell experiment and increased the concentration of the anode (Mg) and the cathode was kept at standard conditions. I am unsure about why the cell potential decreased as the ...
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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. ...
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1answer
65 views

Which Half-Reaction to Use? [closed]

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\...
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28 views

Is it possible to make a concentration cell without ion-permeable membrane?

I struggle to understand the use of ion-permeable membrane (or salt bridge). https://en.wikipedia.org/wiki/Concentration_cell If i pour two solutions with different concentration, why do you need the ...
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28 views

How does electrolyte impurities affect the voltage in a voltaic cell?

I'm currently doing my FYP assignment on electrochemistry (predominantly on voltaic cells). As I was conducting my research I managed to come off with this topic as stated in the title, however, I am ...
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Additivity of Electrochemical Potentials

When studying derivation of galvani potential difference from interphase equilibria it was written for example that electrochemical potential of zinc is equal to sum of electrochemical potentials of ...
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What happens inside salt bridges?

I don't understand how a salt bridge work exactly: what happens inside it and how it affect the cell's lifetime. I have already read: Salt Bridges/Porous Disks Salinic bridges in voltaic cells ...
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1answer
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More ions form pairs when concentration of acid increases, does that decrease the speed of reaction?

Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of ...
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1answer
47 views

How to convert cell diagram to a chemical equation?

How would one convert on the right side of the cell diagram: $$\ce{Zn(s) | Zn^2+(aq) || MnO4-(aq), Mn^2+(aq), H+(aq) | Pt(s)}$$ $$ \begin{align} \ce{Zn(s) &-> Zn^2+(aq)} \tag{ox}\\ \ce{MnO4-(aq)...
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Effect of concentration on voltage from the perspective of energy

As I understand it, the voltage in an electrochemical cell is due to the electrons transferred having a decrease in electrical energy as they go from one species to another. I assume that this change ...
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2answers
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How is Electrode Potential Developed on Inert Electrode?

How does redox couple develop its potential if electrode isn't the part of the redox system like platinum in SHE or Cl2/Cl- in water solution for example? Usually it is discussed how electrode ...
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Vanadium redox battery… why not nitrogen redox battery OR iron redox battery?

Vanadium redox battery operating on $$ \begin{align} \ce{V^2+ -> V^3+ +e-}\\ \ce{VO2^+ +e- +2H^+ -> VO^2+ +H2O} \end{align}$$ because Vanadium has multiple oxidation states. How about nitrogen ...
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84 views

Kohlrausch's Law [closed]

What is the proof of Kohlrausch's Law of Independent Migration of Ions? How did Kohlrausch calculate the limiting molar conductance of a weak electrolyte? I am asking this in context of ...
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1answer
51 views

What is exactly molar conductivity?

I know molar conductivity is conductivity of solutions by molarity, but then I see on next page of my book it defines molar conductivity $\Lambda$ as follows: $$\Lambda = \frac{\kappa a}{l},$$ where $...
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How does the solvation of Zn lead to oxidation? (galvanic cell)

This video explains a causality of electric potential difference in a galvanic cell that's different from what I've understood. The video says that the $\ce{Zn}$ is dissolved into the water, and ...
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1answer
37 views

Electrolysis of water using different kind of electrode and electrolyte safest as possible for splitting demonstration

I am planning to electrolyze water for an experiment. However, I have limited resources and want to do it as safely as possible The resources that I have: $\pu{12 V}$ DC battery Graphite (in the ...
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1answer
33 views

Copper plating with electrolyte not working (Cu(OH)2 vs CuSO4)

I've been experimenting using electroplating, and I recently made a solution by placing two copper pieces connected to a voltage source, in water. I suspect that this created copper(II) hydroxide, as ...
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42 views

What is the difference between these notations and terms?

I can't tell if they're being used interchangeably or if there's some nuanced difference betweem them. Here they are: $E^∘$ $E_0$ $E_h$ $E^⦵$ If I understand correctly, electrode potential is the same ...
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If the current is kept to zero in a potentiometric cell then how do electrons move from one electrode to the other? [closed]

If the current is kept to zero then how do electrons move from one electrode to the other electrode? How would the reduction happen if electrons don't move from one electrode to the other electrode?
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142 views

Are we technically reducing electrodes/wires for the instant that an electron passes through them?

In lecture I was taught that, in a galvanic cell at standard conditions, platinum is often used as an inert electrode when the species being oxidized or reduced exists only in solution, because ...
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How to run electrochemical tests on Microorganism (bacteria in a medium)?

I am trying to run some electrochemical tests(e.g.CV (Cyclic Voltammetry) & EIS (electrical impedance spectroscopy)) using half cell configuration on micro-organisms (e.g.bacteria). The bacteria ...
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Does a change in oxidation number in a redox reaction mean that an actual electron transfer occured?

Oxidation numbers are fictitious charges that pretend the entire molecule is an ion i.e. it artificially localizes electrons onto atoms within a single molecule. In a redox reaction, we find that an ...
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1answer
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Would ionic conduction be halted by shielding at the electrodes?

I've done this experiment myself and seen it front of my eyes. Set up a basic circuit with a battery, an LED, and connect the circuit with a salt-water solution and copper wire. The LED lights up. If ...
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How do I write a balanced redox reaction for the oxidation of chalcocite [(Cu2S) (s)] by O2 (g) to form Cu2+ (aq) and SO42- (aq) [closed]

I'm not exactly sure how to get the oxidation and reduction half reactions. Any help will be much appreciated!
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79 views

How can platinum function as an “inert electrode” while having a standard reduction potential of 1.2 from its 2+ oxidation state?

In lecture I was taught that, in a galvanic cell at standard conditions, platinum is often used as an inert electrode when the species being oxidized or reduced exists only in solution, because ...
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125 views

How exactly does electrolysis occur if the molar conductivities of cation and anion are different?

I'm having trouble wrapping my head around Kohlrausch law of infinite dilution and molar conductivities in general. For a salt $\ce{AB}$ the molar conductivity at infinite dilution can be expressed as ...
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77 views

Calculating the potential of an electrochemical cell (Nernst equation)

This is the problem: Calculate the ${E_\mathrm{cell}}$ (not ${E°}$) at 25°C. I found that the reaction is $$\ce{Cu(s) + Fe^2+(aq) -> Cu^2+(aq) + Fe(s)}$$ $\ce{Cu}$ gets oxidized and $\ce{Fe^2+}$ ...
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1answer
52 views

What is the voltage of an electrochemical cell at equilibrium?

I am having a hard time understanding what happens at equilibrium in an electrochemical cell (a full cell with two electrodes). At equilibrium, according to Nernst equation, the cell potential is $E_{...
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14 views

How to use anodic and cathodic overpotentials to calculate electrolytic energy efficiency?

I am trying to calculate the energy efficiency for $\ce{CO2}$ reduction to formate, coupled to water oxidation based on literature data. $$\ce{CO2 + 2e- + 2H+ -> HCOOH}$$ $$\ce{H2O -> 2H+ + 1/...
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Why transition metal chloride complex have lower reduction potential than metal aqua ions?

Why transition metal chloride complex have lower reduction potential than metal aqua ions? For example: $$ \begin{align} \ce{Au^3+(aq) + 3 e- &-> Au(s)} &\quad E^\circ &= \pu{+1.52 V}\...
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How can I convert cathodic energy efficiency to overall energy efficiency?

Im working on calculation which involve the energy efficiency of producing formate by CO2 electroreduction. I wonder how to convert the reported cathodic energy efficiency (71%) of papers e.g (1) this ...

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