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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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4answers
280 views

Is there any electronic component to water conductivity?

Answers to Decrease in temperature of a aqueous salt solution decreases conductivity indicate that the electrical conductivity of salt solutions arises from the mobility of ionic species and therefore ...
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3answers
73 views

How Can I Induce Corrosion Electrochemically?

I'm very interested in measuring corrosion in metal alloys, particularly in salt solutions. I understand metals corrode over time, however, I was wondering if it's possible to electrochemically "speed ...
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1answer
25 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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1answer
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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1answer
35 views

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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0answers
27 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 $\ce{Cu}$ ...
1
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1answer
26 views

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 ...
2
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1answer
288 views

What does the osmotic pressure do in an electrolytic solution?

I have learnt that in an electrochemical cell, the osmotic pressure in the solution hinders the flow of ions from the electrode to the solution, rather some ions may accumulate on the electrode ...
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0answers
12 views

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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0answers
10 views

Deodorants and it's electrical conductivity [on hold]

Do deodorants conduct electricity? If so how much it conducts when compared to Salt water?
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0answers
47 views

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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0answers
18 views

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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0answers
27 views

“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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0answers
24 views

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 ...
1
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1answer
59 views

Why do power requirement figures for water electrolysis on the web seem to be wrong?

I need to calculate the power needed to electrolyse 1 mole of water for a project. We will either use Polymer Electrolyte Membrane Electrolysis or Alkaline Water Electrolysis, they operate on 1.75V-2....
5
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2answers
2k views

Difference between intercalated lithium and metallic lithium (Li-ion batteries)

I have a question about Li-ion batteries. I sometimes see the two terms - intercalated lithium and metallic lithium - used when talking about this type of batteries and I was wondering what is the ...
3
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1answer
46 views

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 ...
1
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2answers
152 views

Galvanic Electrochemical Cell Without half cells

Is it possible to create a galvanic cell without a half cell? In the book I was reading, Illustrated Guide to Home Chemistry Experiments, the following lab (Laboratory 16.4) was suggested: add 2M ...
2
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1answer
31 views

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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1answer
73 views

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 ...
4
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1answer
92 views

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,...
3
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2answers
3k views

Why does the cathode have to be made out Cu in a Zn-Cu voltaic cell?

The classic voltaic cell has a $\ce{Zn}$ anode and $\ce{Cu}$ cathode. The reduction half reaction occurring at the cathode combines aqueous copper ions and electrons supplied by the anode to form ...
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2answers
789 views

Nernst equation for a fuel cell when gases are stored separately

I have run some tests with a PEM fuel cell and the voltage we have found was $1.44\ \mathrm{V}$. Given that the standard potential for a fuel cell is $1.229\ \mathrm{V}$ what is causing the difference ...
2
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1answer
70 views

Na Cl battery within Zn Cu battery?

https://youtu.be/iHBz77E625o In this video there are pieces of matboard that are soaked in water saturated with NaCl. The pennies themselves are made of zinc and copper. With the electrical energy ...
0
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1answer
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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2answers
97 views

No current in homemade galvanic cell

I built a galvanic cell using 0.01 M solutions of copper sulfate and zinc sulfate. I used copper and zinc electrodes and immersed them into the proper solutions (copper into copper sulfate, zinc into ...
0
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1answer
41 views

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 ...
0
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1answer
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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0answers
12 views

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 ...
1
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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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0answers
34 views

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 ...
10
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2answers
6k views

Why does increasing number of salt bridges increase voltage of electrochemical battery?

In an experiment, I set up a cell with lead nitrate (w/ lead electrode) and zinc sulfate (w/ zinc electrode), with a salt bridge containing potassium nitrate. I observed that by increasing the number ...
2
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1answer
59 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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0answers
19 views

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?
2
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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 ...
0
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0answers
23 views

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 ...
0
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1answer
85 views

Does reduction/ oxidation take place separately at a half cell electrode?

In the redox reaction chapter, we learn that oxidation and reduction go hand in hand. The oxidising agent oxidises by accepting the electron released by the reducing agent and gets reduced in the ...
2
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1answer
67 views

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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0answers
35 views

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 ...
5
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3answers
8k views

Express the maximum work from a voltaic cell

The net cell reaction of an electrochemical cell and its standard potential is given below: $$\ce{ Mg + 2Ag+ ->Mg^{2+} + 2Ag} \ \ \ \ \ \ \ \ E^\circ=3.17\:\mathrm{V}$$ The question is to find the ...
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3answers
29k views

Why is the reaction between potassium permanganate and hydrogen peroxide spontaneous?

When hydrogen peroxide is mixed with potassium permanganate, oxygen gas and water vapour are formed, according to the reaction (source): $$\ce{2MnO4- + 3H2O2 -> 2MnO2 + 2H2O + 3O2 + 2OH-}$$ This ...
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0answers
35 views

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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1answer
87 views

Pale blue species forming during electrolysis of NaHCO3

I have a solution of 3500 ml $\ce{H2O}$ + 454 g $\ce{NaHCO3}$ in electrolysis at a potential of 12.5V using a lead anode and copper cathode. The surface areas aren't measured but they are enormous. I ...
0
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1answer
34 views

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^\...
0
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1answer
2k views

Changing Temperature of a Galvanic/Voltaic Cell: Should I wait for the electrodes to also change in temperature?

I'm conducting an experiment where I change the temperature of the sulfuric acid in a lead acid storage cell. My one question in controlling the variables is that should I let the electrodes also ...
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1answer
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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1answer
181 views

Do We change sign of electrode potential when reversing an equation?

I have a cell equation as: $$\ce{2Cr^0 + 3Cd^2+ -> 2Cr^3+ + 3Cd^0}$$ I am provided the standard reduction potentials as: $$\begin{align}\ce{Cd^2+ + 2e- &-> Cd} && E= \pu{-0.4V}\...
2
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1answer
103 views

Cathodic protection of active metals

Cathodic protection prevents the removal of positive form the metal surface by applying a negative charge to the metal. Is is possible to prevent the reaction of an active metal (i.e. sodium) with ...
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0answers
31 views

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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0answers
18 views

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 ...