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
191 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
41 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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29 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
170 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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30 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
209 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
95 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
67 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
49 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
47 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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31 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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2answers
165 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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23 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
156 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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0answers
21 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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32 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
219 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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1answer
57 views

Why does iron oxide form hydrous iron oxide while chromium oxide does not?

Both Cr2O3 and Fe2O3 share a similar structure, and both can form some sort of passivating layer, but only one of them hydrates, thus turning into rust and providing a pathway for more water and O2 to ...
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0answers
34 views

Will changing the salt in the salt bridge change the voltage produced in a galvanic cell?

I have used zinc sulfate and copper sulfate as the solutions, and used zinc and copper electrodes. For salt bridge I took lithium, potassium, calcium, sodium and zinc nitrates. The results are as ...
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1answer
66 views

What is the anodic reaction of aluminum in water

Standard electrode potentials are reported for materials that are not usable as actual electrodes in water because they react spontaneously and rapidly. https://www.engineeringtoolbox.com/electrode-...
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1answer
27 views

Do the cathodes of all batteries increase in mass as the battery is used?

I understand the mechanism behind the cathode's increasing mass in many batteries. As the cathode receives electrons, ions are reduced to form atoms. In short, more electrons equals more mass in the ...
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2answers
186 views

Does increasing one of the electrolytes in a galvanic cell increase the voltage?

I would like to know how you could increase the voltage in zinc and copper galvanic cell: $$\ce{Zn(s) + Cu^2+ → Zn^2+ + Cu(s)}$$ I know that temperature and surface area is a factor that affects the ...
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0answers
37 views

Out of KCl, CaCl2, MgCl2, NaCl, which causes the greatest corrosion rate of iron and why?

I know that salts act as an electrolyte in a redox process and rusting of iron, where iron loses electrons and oxidizes, and oxygen gains electrons and reduces. I did an experiment with KCl, NaCl, ...
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26 views

Variation of battery potential with current density

It is found experimentally that the potential of an electrochemical cell with applied current density varies as follows: To produce the passage of current through a cell it is necessary to apply a ...
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1answer
87 views

Using PV = nRT to solve an electrolysis problem

Question: Two electrolytic cells are connected in series (the same current passes through each cell). One cell for the electrolysis of water produces $\pu{100 cm^3}$ of oxygen, measured at $\pu{273 K}$...
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1answer
40 views

Decline in current during electrolysis

I observed a sharp decrease in the current when I carried out the electrolysis of water. Just to set the context, I used a voltage of $\pu{12V}$ and the concentration of my electrolytes were $\pu{0.15 ...
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41 views

phenolsulphonic acid

Phenolsulfonic Acid( PSA) is produced after sulphonation of Phenol at around 100 degrees. They use this product in tinplating. Once a stable PSA is formed after sufficient reaction , unreacted ...
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1answer
41 views

Electrochemistry - reduction potentials - an IB Chemistry Question [closed]

I have re-read the Electrochemistry chapter from my textbook just now to remind my self of the exact formulae. I still don't understand how to approach this question, however - how can we work it out? ...
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1answer
547 views

How does precipitate affect cell potential?

A cell is set up with copper and lead electrodes in contact with $\ce{CuSO4(aq)}$ and $\ce{Pb(NO3)2(aq)},$ respectively, at $\pu{25 °C}.$ The standard reduction potentials are: $$ \begin{align} \ce{Pb^...
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78 views

What happens when solution containing two or more cations are electrolysed at an excess potential?

$\pu{250 mL}$ of a waste solution obtained from the workshop of a goldsmith contains $\pu{0.1 M}$ $\ce{AgNO3}$ and $\pu{0.1 M}$ $\ce{AuCl}$. The solution was electrolyzed at $\pu{2 V}$ by passing a ...
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1answer
362 views

Why does the specific conductivity against concentration curve for NaCl curve more than KCl?

I understand why KCl has a higher specific conductivity than NaCl.. but I dont understand why the curvature is more significant for NaCl (KCl is a straight line). Ive provided a picture of this here, ...
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35 views

Could Carbon Monoxide be reduced by oxidising a more reactive metal?

After studying displacement at school, I wondered if it is possible to reduce the toxic gas of carbon monoxide to less harmful and more useful substances, like so: Carbon monoxide + metal -> Carbon ...
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1answer
134 views

calculate cell potential for the voltaic cell where its involving the two cobalt species with Copper

Calculate the cell potential for the voltaic cell that results when the following two half-cells are connected at $\pu{25 ^\circ C}$: (1) A platinum electrode inserted into a solution of $\pu{0.10 M}$ ...
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1answer
111 views

Schrodinger's Equation and Wave Function

So I understand that there exists the shrodinger's equation, which on solving,gives the wave function of an electron. The wave function as I understand, gives all possible information about an ...
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1answer
800 views

NaCl electrolysis with copper electrodes

Considering the aqueous $\ce{NaCl}$ is already concentrated. If we were to use copper electrodes instead of inert graphite electrodes: Would copper react with the evolved chlorine gas to give $\ce{...
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2answers
415 views

Origin of electrode potential and its connection with electric double layer

Recently, I was learning about electrode processes and I came across the topic of "electrode potentials". I understood that at equilibrium, a potential difference was generated at the ...
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1answer
40 views

Why is there no salt bridge for hydrogen–silver bromide cell?

What is the reason there is no salt bridge for this cell? $$\ce{Pt(s) | H2(g) | HBr(aq) | AgBr(s) | Ag(s)}$$
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1answer
65 views

Derivation and visualization of cell potential dependency on temperature and entropy

Working from the thermodynamic identity $$\Delta{S} = -\left(\frac{\partial{\Delta{G}}}{\partial{T}}\right)_p,$$ is it allowed to integrate both sides to obtain an expression derived from the Nernst ...
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1answer
38 views

Do I have to systematically show the protons in my reaction equation to find the Pourbaix diagram's line equations?

I was trying to get the line equation for the Pourbaix diagram for the couple $\ce{Ni(OH)2}/\ce{Ni}.$ I can write two chemical equations for basic and acidic conditions, respectively: $$ \begin{align} ...
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4answers
810 views

In electrolysis, why does each atom wait to turn into gas until they reach a particular electrode?

More specifically why don't bubbles of both oxygen and hydrogen appear everywhere? If the electricity just breaks apart bonds wouldn’t the hydrogen and oxygen just immediately turn into gas and bubble ...
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1answer
99 views

Why does contaminated brake fluid conduct electricity? Using a voltmeter to test for water contamination in brake fluid

Contaminated brake fluid conducts electricity. In the automotive repair world, brake fluid is considered contaminated by two ways: Brake fluid is hygroscopic. Higher water content in brake fluid ...
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1answer
286 views

EMF - Intensive or Extensive Property

In electrochemistry, I know that standard emf of a cell (also called standard electrode potential (E°)) is an intensive property. But, I wanted to know whether non-standard emf will also be intensive ...
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1answer
122 views

Electrolysis of brine solution gives sodium hydroxide , chlorine and hydrogen gas but catner kellener cell it forms amalgam [closed]

Sodium hydroxide is generally prepared commercially by the electrolysis of sodium chloride in Castner-Kellner cell. A brine solution is electrolyzed using a mercury cathode and a carbon anode. Sodium ...
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16 views

How to estimate gas yield from polarization curve of the electrolyser

A good characterization of electrical properties of the alkaline water electrolysis of the water is its polarization curve. Is there a reasonable way to estimate gas yield for each point of the ...
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1answer
107 views

Electrochemistry -gold recovery

I was wondering how to answer a question I got from my students about the possible recovery of gold from solution. We just finished the reaction between silver ions and copper metal and they wondered ...
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1answer
109 views

How does strong acids conduct electricity in water?

How do strong acids conduct electricity in water? I have just studied ionization of water and I'm confused about some points. First: I know that water ionizes in a very small amount ($10^{-14}$) so ...
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1answer
45 views

Corrosion rate of aluminium

In which conditions the corrosion rate of aluminium is faster? a) acidic conditions b) neutral c) alkaline conditions I know that corrosion can be in a and c cases but I dont know when it'll be faster....
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2answers
72 views

How do oxide formations affect voltaic cells?

I asked a question previously on here but still have some confusion. To briefly summarize, I made a voltaic cell for a school project with 0.1 M copper nitrate and varying concentrations of aluminum, ...

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