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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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Where do negative ions migrate from the salt bridge to which electrode in the voltaic cell?

In the voltaic cell with Mg/Mg+2 and Ag+/Ag, I am not sure whether the ions move from the salt bride to the Mg cathode or the Mg+2 cathode. I distantly recall my teacher saying the cathode (in this ...
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Electrochemistry problem- delta G [on hold]

What is delta G per mole of dichromate ions for the reduction of dichromate ions, Cr2O7 2-, to Cr 3+ by bromide ions, Br-, in acidic solution? (Hint: Use the standard cell potential.) (a) +26.3 kJ (...
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Water colour changes to yellow after electrolysis [on hold]

A salesman recently conducted electrolysis experiment on 4 samples of water-- river water,tap water, his own water and water from Aquaguard RO filter. The colour change after electrolysis on different ...
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26 views

Why electrons move to Cu in galvanic cells?

I'm student who learning about chemistry, and I got problem about understanding why electorns move to Cu in galvanic cells. Let's think the reason for electrons going to Cu is that the standard ...
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28 views

Reaction between copper and silver(I) nitrate in aqueous medium

What is the reaction between $\ce{Cu}$ and $\ce{AgNO3}$ taking place in aqueous medium? The answer given was: "Only" oxidation of $\ce{Cu}.$ My concern is: how is only oxidation of $\ce{Cu}$ ...
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24 views

Decrease in molar conductivity with increase in concentration

Why does molar conductivity $Λ$ for strong electrolytes decrease with increase in concentration? I mean, more concentration would mean higher number of solute particles present in the solution, and as ...
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Electroplating on Brass - Specifics [on hold]

I'm familiar with the basics of electroplating but not with the specifics; I want to do chrome plating on brass to give it a finish, I know that first there is an acid bath, then nickel plating, and ...
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How to reverse copper electroplating?

We did a lab where we built a simple electrolytic cell. In a beaker was a solution of $\ce{CuSO4}.$ A copper strip (anode) and a copper wire (cathode) was place in it. A wire connected the copper ...
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Deodorants and it's electrical conductivity [closed]

Do deodorants conduct electricity? If so how much it conducts when compared to Salt water?
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Finding the ionic product through conductivity [closed]

The conductivity of saturated barium sulphate solution at $\pu{25 °C}$ is $\pu{3.6e-4 S m^-1}.$ The water from which the solution was made had conductivity of $\pu{0.6e-4 S m^-1}.$ What is solubility ...
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How does a pH glass electrode work?

Every source I read mentions the potential difference building up at the glass membrane (according to the Nernst equation). But how is this difference actually measured? Sticking an electrode into a ...
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“Hairy” corrosion on anodized alu-part in water

I got a water tank with a mechanical assembly in. The assembly consist of parts of anodized aluminium mounted on stainless steel plates (AISI 304). This is submerged down in fresh water. The tank is ...
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How do fuel cells work? [closed]

I have been reading an introductory book on fuel cells, and it's indicated that SOFC need to be brought to $\pu{600\! -\! 1000 ^\circ C}$ to be more efficient. So, my understanding is that if I want ...
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1answer
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How do I remove tetrabutylammonium perchlorate from an organic synthesis?

I am trying to remove tetrabutylammonium perchlorate (TBAP) from an organic synthesis where TBAP was used as an electrolyte. I am working with compounds containing the amide group. I have used flash ...
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1answer
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What should be the order of specific conductance (κ) of floride, chloride and bromide ions?

The equivalent conductance order is $\ce{Br-} > \ce{Cl-} > \ce{F-}$. $$Λ = \frac{κ}{c},$$ so $Λ$ is proportional to specific conductance? But in ion chromatography we get peak area where $\ce{...
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How does equalizing voltage for lead acid battery depend on the temperature?

I am using advanced lead-carbon batteries (these ones) in an off-grid solar system. The spec specifies equalizing voltage 14.1 V for 12 V block @ 25 °C (77 °F). I keep the batteries in an outdoor shed,...
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34 views

Why does H2O electrolysis produce O2 on the anode instead of H2O2

If the oxidation of $\ce{H2O}$ produces $\ce{OH-}$ ions and the anode separates electrons from them leaving neutral $\ce{OH}$ molecules, why don't they bind to each other covalently?
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Why would water, and not saltwater, undergo electrolysis?

I am attending a cram school and there was a question that goes: Electrolysis decomposes chemicals by passing an electric current through a liquid or solution containing ions. Which of the ...
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Displacement reaction

I have read from somewhere that aluminium is unable to displace zinc from its solution due to formation of a layer of aluminum oxide which has lower E° than zinc . But this layer can be broken down ...
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42 views

Salt bridge confusion :(

How exactly does a salt bridge close the circuit? I understand its role of neutralizing the solustions but I can't see how it forms a complete circuit. Do charges flow back to the anode through it? ...
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What could be causing my cyclic voltammograms to have a sloped scan?

I am running a CV (cyclic voltammogram) in a two compartment bulk electrolysis cell with pH 7 phosphate buffer (0.5 ion concentration) and a napheon membrane separating the two compartments. I'm using ...
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1answer
33 views

Electrode potential for metal-metal ion and metal-metal insoluble salt-salt ion electrode

So I read it in a book that The potential of metal-metal ion electrode and metal-metal insoluble salt-salt anion electrode is same while their standard potentials are not same. Standard potential ...
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What Ion gets reduced in this aqueous electrolysis?

In an electrolysis of tin(II) iodide ($\ce{SnI2}$) with led cathode and nickel anode, why is it that the tin ion gets reduced and not the nickel ion?
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Electric potential of a redox reaction (without solids)

I need someone to help me with a problem: We have a solution which is $\pu{0.1 M}$ of $\ce{KMnO4}$ and $\pu{0.1 M}$ $\ce{Fe^2+}$ and has $\mathrm{pH}=0$. Given the electrical reduction potential of ...
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2answers
240 views

Leaching of copper using zinc

Why can we not use zinc for extracting copper from a solution containing $\ce{Cu^2+}$ ions even though it is a better reducing agent than $\ce{Fe}$? I am studying metallurgy and I cannot understand ...
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Why does the following “Battery” experiment work?

I did the following experiment: Experimental setup: Two electrodes (one made out of Iron,the other made out of Copper) are put into a (bluish) Copper(ii) sulfate lotion. Then, one connect a ...
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Why do Cu⁺ ions spontaneously form copper metal and Cu²⁺ ions in solution?

The standard electrode potentials for three reactions involving copper and copper ions are: $$ \begin{align} \ce{Cu^2+(aq) + e- &-> Cu+(aq)} &\quad E &= \pu{+0.15 V} \\ \ce{Cu^2+(...
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Can carbon dioxide be used as oxidant for iron?

Determine whether it is possible for $\ce{CO2}$ to be an oxidant for $\ce{Fe}$. Justify your choice by comparing the corresponding half reactions. I found the following half-reactions, both on ...
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How can I find the emf of a cell given the individual reduction and oxidation reactions and their respective potentials? [duplicate]

If I am given the individual oxidation and reduction half-equations, how can I find the emf of the combination? For example: $$ \begin{align} E^\circ(\ce{Fe^3+}/\ce{Fe^2+}) &= \pu{0.77 V}\\ E^\...
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39 views

In a galvanic cell, why do electrons move through the wire from zinc to copper?

I understand that there is aqueous $\ce{Cu^2+}$ in this scenario which pulls on the electrons from the zinc causing the electrons to move through the wire, but how does the electronegativity of $\ce{...
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Degradation of carbon anode in electrolysis of copper sulfate

I'm electrolysing a copper sulfate solution with a 12 volt DC supply using two carbon electrodes. The anode is reducing in mass and becoming thinner. Is there any way I can overcome this problem?
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Electrodes of the second kind

An electrode of the second kind consists of a metal sheet coated with a layer of a slightly soluble salt of the metal of which it is made, immersed in an electrolytic solution: the last one must have ...
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Why is it bad to charge a phone to 100%? [duplicate]

I see everywhere that a phone should ideally be between 20 and 80% to work efficiently, but I don't understand why, in an electrochemistry point of view. (I'm not talking about the fact that ...
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1answer
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Which conductivity law should I use to calculate the conductivity of a solution with high/low concentration?

I have a set of NaCl solutions with concentrations ranging from 0.05 M to 0.1 M. I have been trying to calculate the conductivity of these solutions and compare the obtained values with the ...
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half equations for a lead-acid cell

we are learning about galvanic cells. I would like to know the half equations and overall equation that occurs in this lead acid cell. so far my understanding for the oxidisation section is that in a ...
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Negative Voltage for Full Redox Reaction?

I have a question about voltages including redox reactions. I know that half equations may have negative voltages when choosing what is undergoing reduction, and what is undergoing oxidation in a ...
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1answer
34 views

Electrolytes are ionic compounds that conduct electricity [closed]

Electrolytes are ionic compounds that conduct electricity, or the flow of charged particles, when dissolved in water. This occurs via the separated ions acting as those charged particles, or charge ...
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Rate of cathodic reaction vs Tafel slope

One of my reference engineering books says that for the cathodic protection process (in seawater): Al $\rightarrow$ Al$^{3+}$ + $3e^-$ (anode, setting the protection potential at about -900 mV SCE) ...
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1answer
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What is the balanced chemical equation for a redox reaction between a lithium-cobalt battery and a graphite electrode?

I'm doing a project for my last year of secondary school on lithium cobalt batteries and got confused about the equation. This is the only equation I can find (source: www.science.org.au): \begin{...
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Current and reversible heat in battery reaction

In the book Battery Technology Handbook by Kiehne [1] (Google Books) on page 21, equation (32): The reversible heat effect per time unit can be related to current flow, because each multiple of the ...
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Energy balance in battery thermodynamics

I am trying to understand the derivation of a general energy balance in battery thermodynamics. The following relation is frequently found to determine the heat generation of a battery: $\dot{Q} = \...
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1answer
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Balancing redox equation with oxygen on both sides?

The problem is to balance this equation in an acidic medium. $$\ce{As2O3 (s) + NO3- (aq) -> H3AsO4 (aq) + N2O3 (aq) }$$ However, I am getting stuck balancing the oxygens after dividing them ...
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Can I make an ionic liquid from glycerin and zinc sulfate?

Can I make an ionic liquid (dissolved salt without water) by combining zinc sulfate and glycerin? I've been using 1 M $\ce{ZnSO4}$ as my electrolyte in supercapacitor study. Works very well up to ...
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1answer
65 views

Why should I not use different battery types together?

Everyone knows about this but I'm curious about why one should never mix batteries of different types. By type I mean the same shape of the cell like AAA but with different chemical reactions and ...
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1answer
111 views

What happens if you put a piece of copper into a solution containing Al3+ ions?

This is a question in my studies, and I am a little bit confused! I would think it happens nothing because copper is below aluminium in the reactivity series, right?
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1answer
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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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Is it possible to electroplate from a gallium anode?

I have been looking at some papers on electro-deposition of iron gallium alloys and these all use solutions made up of Fe and Ga sulphates. I am just curious as to why perhaps an anode made of one of ...
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1answer
126 views

Replacing Salt Bridge with Platinum Sheet

What would happen, if in a galvanic cell, the salt bridge is replaced by an inert platinum sheet? Would charges accumulate on the sheet? Would the cell still work, and produce less emf than earlier, ...
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Regarding Standard Electrode Potentials

If the standard hydrogen electrode (SHE) is set arbitrarily to have a potential that is equal to 0 V, and has an absolute real potential. Then, in electrochemistry, how are the electrode potentials of ...
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Polarity of Cell Electrodes [duplicate]

I understand that the anode in a galvanic/voltaic cell is considered to be 'negative' while the cathode is 'positive'. However, in an electrolytic cell, the cathode is 'positive' while the anode is '...