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
31 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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23 views

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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114 views

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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25 views

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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29 views

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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38 views

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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26 views

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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45 views

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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25 views

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
70 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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29 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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30 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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494 views

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
33 views

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
60 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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23 views

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
53 views

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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1answer
117 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
43 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
67 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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45 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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2answers
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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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2answers
149 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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3answers
88 views

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
29 views

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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2answers
52 views

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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84 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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1answer
143 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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1answer
105 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
119 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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16 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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2answers
40 views

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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26 views

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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1answer
136 views

Electrolysis of copper sulphate using copper electrodes: Mass lost from anode is greater than mass deposited on cathode

In short, the aim of my experiment is to determine how the concentration of sulphuric acid in solution affects the mass liberated and deposited at copper electrodes, when copper sulphate is ...
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27 views

How to calculate Energy Efficiency of electrochemical production

I'm trying to understand some basic electrochemistry as a non chemist and struggling to find the info online effectively. Its clear that energy efficiency = Energy(useful) / Energy (input). So, I know ...
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3answers
190 views

How does the addition of NaCl to the cathode side effect the potential of a voltaic cell: Zn(s) | Zn2+(aq) 0.1M || Cu2+(aq) 0.1M | Cu(s)

By addition of $\ce{NaCl}$ to the $\ce{Zn}$ side of the cell, I observed precipitation of $\ce{ZnCl2}$. I measured the voltage to $\pu{1.05 V}$ before adding $\ce{NaCl}$ to the cathode side, I then ...
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2answers
73 views

Temperature Dependence of The Conductivity of Electrolytic Solutions

I have learned in my chemistry text books that the conductivity of electrolytic solutions increase with the increasing of temperature because the ions of electrolytic solution move faster by getting ...
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1answer
64 views

What does onset of oxidation mean in Cyclic volammetry

I've read a few posts on here on how to calculate onset of oxidations in Cyclic voltammetry. However, I dont know what it actually means when comparing the onsets of oxidations of two different ...
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1answer
24 views

Is there a generalize-able relationship between Ecell and T for a galvanic cell?

Is there a generalize-able relationship between Ecell and T for a galvanic cell (assuming constant concentrations of all components)? (ie: higher temp = bigger/smaller Voltage) Or is it entirely ...
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1answer
48 views

If we put an metal electrode in water with no metal ions present potential should tend to minus infinity?

If we consider an equilibrium between metal electrode and its ions in solution we know that equilibrium potential is proportional to activity of ions in solution from Nernst equation. Since this ...
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2answers
45 views

Is the electric conductivity of chlorine ions influenced by its oxidation state?

I'm a high school student researching the conductivity of electrolyte solutions. In this excerpt of the CRC Handbook, I noticed that different ions containing chlorine have different limiting molar ...
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22 views

What Determines the Value of Symmetry Factor (Charge Transfer Coefficient) and What is its Connection With Transition State Structure/Configuration?

I know that symmetry factor determines symmetry of energy barrier for reduction and oxidation. It is an fraction of electric potential energy difference of electron in electrochemical double layer ...
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149 views

Orientation of external cell when voltage is supplied by it to voltaic cell so as to oppose its cell potential

Given below is a page from our Chemistry Textbook: As it can be seen, the direction of $E_{ext}$ in figure $3.2(c)$ is opposite to the direction in figures $3.2(a)$ and $3.2(b)$. I understand that $...
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22 views

Electorchemical Systems (Newman 3rd edition) problem solving

I am trying to solve the very first problem (Problem 1.1) of Newman 3rd edition book. The book problem goes as follows: 'Starting with the following equation for the concentration overpotential: $\...
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2answers
121 views

How is it Possible to Measure Electrode Potential?

It is known that potential difference on metal/electrolyte or any kind of interphase can't be measured since voltmeter needed to measure it is made of metal which would in contact with metal and ...
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20 views

Why Do Electrodes Develop Equilibrium Potential?

When we place metal electrode in solution of its ions, metal ions from metal have tendency to go into solution and ions from solution tend to enter the metal lattice. My question is what is a cause of ...
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28 views

Why is zinc electrode at a higher potential than copper electrode in a galvanic cell?

I read somewhere that this happens because of better shielding of outer s electrons due to completely filled d orbitals of zinc, but I didn't understand it. Since Zn has an electronic configuration of ...
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2answers
181 views

What if kinetic energy of ejected electron = 0

When hf ≥ work function, Then the electron still comes out. So, if I say kinetic energy of ejected electron = 0, it should still come out. Right ? Then, how does the electron even move out or gets ...

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