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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20 views

Reduction Potential of Fe[(C2O4)3]3- /Fe2+

I need the standard reduction potential of the couple $\ce{[Fe(C2O4)3]^3-}$ / $\ce{Fe^2+}$ . I searched for it in many reduction potential tables on the web in vain. If someone can tell me where to ...
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How can the difference between surface energy and electrostatic repulsion be calculated in electroplating?

When metals are electroplated unto surfaces, there are a myriad of forces at play. To set a clear example, if one were to electroplate a magnet with a diamagnetic metal such as bismuth, there will be ...
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Electrodes selection in electrolytic cell [closed]

In electroplating, why is metal to be electroplated connected to positive terminal of the battery only????
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62 views

What is exactly molar conductivity? [closed]

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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Why is HNO3 a stronger oxidising agent than H3PO4?

Why is $\ce{HNO3}$ a stronger oxidising agent than $\ce{H3PO4}$? $\ce{N}$ and $\ce{P}$ have the same oxidation number. Is it the electronegativity difference between $\ce{N}$ and $\ce{P}$?
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Entropy change during electrolysis of water

Consider the electrolysis of water reaction: $$\ce{H_2O -> H_2 + 1/2O_2}$$ At room temperature and atmospheric pressure, the change in enthalpy of this reaction is $\Delta H = \pu{+286 kJ mol-1}$. ...
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1answer
82 views

Considering Gibbs energy or electrode potential to find disproportionation tendency

The following data was given (without the asterisks and footnote) asking us to find the oxidation states that would have a tendency to disproportionate - By tendency to disproportionate, I understood ...
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Thickness of proton exchange membrane (Nafion)?

I am looking into using a proton exchange membrane for a bio-energy cell experiment. Previous scholars have been using Nafion as a PEM to place between the anode and cathode (air-cathode). the ...
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2answers
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[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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How would you make your pool Zn ionizer? [closed]

So I'm trying to make a Zn ionizer for my pool, much like the Cu ionizer. As the benefits vs side effects with Zn are far better. Just seems to make a cloudy mess. Anyone know a way around this cloudy ...
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1answer
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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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Why can we disregard stoichiometric coefficients when computing reduction potentials?

A $\ce{Cr(s) | Cr^3+ || Cd^2+ | Cd(s)}$ galvanic cell has redox half reactions: $$ \begin{align} \ce{Cd^2+ + 2e- &-> Cd(s)} &\quad E^\circ &= \pu{-0.4 V}\tag{R1}\\ \ce{Cr^3+ + 3e- &-...
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33 views

Conductance and concentration of a strong electrolyte

I learnt that with the increase of concentration, conductance of tr electrolyte decreases. While looking for the reason I found in my textbook that if concentration increase, amount of ions increases ...
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Electrochemical etching of silicon

I am doing some research on porous silicon in electrochemical biosensors. I have come across the electrochemical etching method to produce porous silicon for the biosensors. I have also come across ...
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1answer
2k views

faraday laws of electrolysis

I came across this question: A quantity of electrical charge that brings about the deposition of 4.5 g $\ce{Al}$ from $\ce{Al^{+3}}$ at cathode will also produce the following volume (STP) of $\ce{H2}...
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642 views

The spontaneity of a redox reaction

Suppose we have a redox reaction and we want to see in what direction the reaction is spontaneous. We do this by comparing the standard reduction potentials of the sub-reactions available in the main ...
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Cathodic protection

My doubt is regarding cathodic protection. I have understood protection of metal by using sacrificial anodes as its a clear example of an electrochemical cell. However, in ICCP we make a less reactive ...
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2answers
95 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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In a perfect electrolytic cell, would the anode and cathode change by the same amount

If I had a theoretically perfect electrolytic cell, such as one with Copper anodes and cathodes, and a copper nitrate solution, over a given time period with a voltage applied, would the change in ...
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Potential difference between metallic electrodes in water

If I dip two pieces of metal in tap water I measure a potential difference between the two electrodes with a common digital voltmeter. For example, for Cu and Al I measured 0.55 V and for Cu and Fe I ...
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1answer
83 views

Why Does Electrical Work Cause Changes in Internal Energy of the System? [closed]

If we look at system at constant temperature and volume which is galvanic cell, first law of thermodynamics states: $$ dU = dQ + dW'$$ Where W' is electrical work exchanged with surroundings and Q is ...
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43 views

What are the half-cell redox reactions of water in different pH solutions?

While reading about the electrolysis of aqueous sodium chloride solution, I realized that the half-cell reactions depend on the pH of the solution. According to my understanding, the following ...
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Why are conductance and conductivity additive in nature? [closed]

In my book, it is written that: $κ_{electrolytic solution} = κ_{electrolyte} + κ_{solvent}$ $G_{electrolytic solution} = G_{electrolyte} + G_{solvent}$ Where $κ$ and $ G$ are conductivity and ...
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What are the similarities / differences between the terms anode / cathode and oxidizing agent / reducing agent? [closed]

I'm kind of confused on how to distinguish the terms anode and cathode from oxidizer and reducer or oxidizing agent and reducing agent. Some references prefer to use one over the other in discussions ...
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2answers
145 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
61 views

Calculating time needed to coat an object using the process of electrolysis

Suppose we have an object with a surface area of $S=\pu{1.5 dm2}$, and we need to coat it with hard chrome. The thickness of the coat should be $d=\pu{80 \mu m}$. The mixture used for coating is of ...
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37 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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What Does Electrical Work Represent in Context of Electrochemical Cells?

If cell operates reversibly than change in Gibbs energy of system equals electrical work of the cell. As far as I know electrical work is work done by electric field when charge moves between certain ...
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2answers
91 views

How to measure chlorine content using ORP sensor?

In my project I need to measure pH, turbidity, and chlorine level of treated drinking water. I found sensors for measuring pH, turbidity, and also chlorine. The actual problem begins is that the cost ...
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2answers
372 views

Does a zinc metal coating react with coffee in a coffee grinder?

I'm restoring an old coffee grinder and I want to give the grinder mechanism a nice zinc / silver coating. But I read it is not safe for zinc to be in contact with acidic foods. When I look at the ...
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1answer
19 views

Can you create a temporary bond in between an atom and a filter by electrically charging the filter?

I want to be able to turn a filter on and off by electrically charging the filter so that it creates a temporary bond that blocks up the filter then, by discharging the filter, releasing the temporary ...
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1answer
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Enthalpy of Reaction and Efficiency of Electrochemical Energy Devices

For electrochemical energy devices such as batteries or fuel cells working reversibly, efficiency is defined as: $$ \eta = \frac {\Delta_rG^⦵} {\Delta_rH^⦵} $$ Since cell operates reversibly Gibbs ...
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Calculating the value of equilibrium constant using cell potential differences

Calculate $\Delta G^\circ$ and $K$ at $\pu{25 ^\circ C}$ for the following reactions. (a) \begin{align} \ce{Cu^2+ + 2e- &-> Cu}\quad E^\circ = \pu{0.34 V} \\ \ce{Fe^3+ + e- &-> Fe^2+}\...
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Grotthuss mechanism and diffusion of hydroxyl ions

Does a new water molecule form and result in a new hydroxide being formed?
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36 views

How does the membrane potential change so drastically during an action potential?

I understand that the Nernst potentials $$V = \frac{k_\mathrm{B}T}{e} \ln\left(\frac{c_\mathrm{out}}{c_\mathrm{in}}\right)$$ for all ions inside and outside a cell barely change when an action ...
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2answers
1k views

How does an anode metal come into solution if it cannot react with an electrolyte?

From what I understand, an anode material is chosen so that it does not react with the anode electrolyte solution. I was just wondering, then, that when you have a galvanic cell which has a Mg metal ...
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1answer
49 views

How is it possible to electroplate using an Al3+ solution, when water is a stronger oxidant?

Suppose that I wanted to electroplate Al(s) onto a Cu(s) Cathode, (using an Aluminium Nitrate solution and Al(s) anode). At standard conditions, Al(s) is the strongest reducing agent, which is good. ...
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What is a suitable material for a cathode in electroplating experiment?

I am going to do an electroplating experiment, whereby I will be using a Cu(NO3)2 solution to plate onto a cathode. What is an easily accessible cathode which I can use for this? Would a strip of Ag (...
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54 views

Why do galvanic cells need a salt bridge while electrolytic cells don't?

I see the questions of why a galvanic cell needs a salt bridge and why a electrolytic cell doesn't need a salt bridge being answered separately but I still can't grasp why you are not allowed to mix ...
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2answers
81 views

Will an alloy leaching in an acid act as both anode and cathode?

If an alloy is placed in an acid where selective leaching is occurring, will the alloy act as both anode and cathode? If the alloy does act as both anode and cathode then will the potential difference ...
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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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35 views

Nernst Equation for an electrolytic NaCl(aq) cell

I am examining a brine cell $\ce{Ti_{(s)}|Cl2_{(g)}|Cl-_{(aq)}||H2O, H+_{(aq)}|H2_{(g)}|Ni_{(s)}}$ with the net reaction: $$ \ce{2 NaCl_{(aq)} + 2 H2O -> Cl2 + H2 + 2 NaOH_{(aq)}} $$ I want to ...
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1answer
219 views

Electrochemistry - Redox & Electroplating

I've stumbled across an electrochemistry problem that I need help on: $$\ce{Fe~|~Fe^{+2}~||~Cl^{-},Cl2~|~Pt}$$ I understood that iron is at the anode and is being oxidized, however I do not know ...
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1answer
1k views

Variable oxidation state of transition metal ions

Transition metals can form stable ions with different oxidation states. But I am confused why doesn't only the most stable state exist. Let me clarify my question more: $$\ce{Ti^{2+} -> Ti^{3+} + ...
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1answer
424 views

Why does magnesium deposit during electrolysis of a molten mixture of MgI2 and AlBr3?

During the electrolysis of mixed salts, I read, and was taught, that the cation with a higher ionization energy would deposit at the cathode. I was also told that you cannot use the standard electrode ...
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1answer
54 views

Need help to calculate results of an electrochemistry cell potential lab work

So, the lab work is this. I made an AgCl electrode of a silver wire by coating it with AgCl. This was done by electrolysis by immersing the wire in HCl and using platinum as a counter electrode and ...
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1answer
22 views

What determines the product at the anode/cathode of a electrolytic cell with an aqueous solution?

If you perform electrolysis on Aqueous Sodium Chloride of various concentrations, how does the product at the anode change but the product at the cathode does not? What is the mechanism behind this ...
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1answer
318 views

Homemade diode working mechanism

Hello, I will list the questions directly, if you want to know details please read below. As in the figure, we have water+baking soda in a plastic cup, there are 2 versions in figure that affects LED'...
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3answers
5k views

How to convert sodium aluminate back to sodium hydroxide?

I had dissolved a bunch of aluminium foil in an aqeous solution of sodium hydroxide. The resulting solution consists mainly of sodium aluminate with very little excess sodium hydroxide. What I want to ...
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How are ions transported in solid state electrolytes?

Consider an inorganic solid state electrolyte in a solid state Li-on battery. It being solid means that the atoms or ions that make up the solid itself are not mobile. Then how do the ions move ...

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