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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Salt bridge in galvanic cell

When we make a galvanic cell using zinc rod (in zinc sulphate solution) and copper rod (in copper sulphate solution), there is a flow of sulphate ions from the copper compartment to the zinc ...
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188 views

What is the substance turning salty water green when electrolysed? [duplicate]

I am a student and I take O.L. Chemistry, in my knowledge I know if I electrolysed concentrated aqueous NaCl solution I should get Hydrogen evolved at the cathode and chlorine at the anode. I did an ...
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Electrochemistry - Understanding Diffusion Potential

I have a big problem trying to wrap my head around this for several hours and I cannot seem to make sense of it. I have to link this scheme with the 3 colored potential profiles on the bottom of the ...
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331 views

Decomposition through thermolysis, electrolysis, photolysis [closed]

What decides whether a compound will dissociate (break-up) under thermal decomposition or photolysis or electrolysis i.e if I am provided with a compound and I'm asked to dissociate it then how will I ...
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2answers
92 views

Why we do not add salt water to the batteries instead of acid? [closed]

Actually I was just thinking that since we add acid to the batteries to increase the conductivity but the thought simply crossed my mind that salt are strong electrolytes so there should be a good ...
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2answers
129 views

Is there a quick way to approximate a logarithm in Nernst equation?

The problem is as follows: In a galvanic cell the cathode is an $Ag^{+}(1.00\,M)/Ag_{(s)}$ half-cell. The anode is a standard hydrogen electrode immersed in a buffer solution containing $0.10\,...
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1answer
2k views

Water colour changes to yellow after electrolysis [closed]

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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3k views

Why the second ionization energy of helium is greater than the first? [closed]

maybe because the first electron has a lower energy. Why does this happen?
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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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2answers
172 views

Does voltage or current matter most when setting up an efficient water electrolyzer? [closed]

I am setting up a homemade water electrolyzer for producing hydrogen gas, which will solely be used by myself for experimental purposes, and have heard the wattage used has a large part to play in ...
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71 views

Predicting directions of redox reactions [closed]

Hello! In this textbook example question, how come the chlorine reaction, which has the greatest reducing power will not react? If it has the greatest E of 1.36 V that means it has most reducing ...
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3answers
407 views

Why doesn't the bulb get brighter if I add another cell in parallel?

Suppose we add another cell and connect it to the same bulb shown(Two cells connected to the same bulb). From the second cell perspective, it sees a resistor and the same chemical reaction should ...
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67 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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1answer
431 views

why does galvanic cell stop working when charge neutrality is not maintained? [closed]

In galvanic cell, salt bridge maintains charge balance between solutions. If there's no salt bridge, charge neutrality will be broken as solution(anode) becomes positive and that of cathode becomes ...
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1answer
3k views

How does a change in the surface area of the electrodes affect the voltage produced by a galvanic cell?

I did a lab where I increased the surface area of the electrodes in a galvanic cell, that resulted in an increase in voltage. However, I have been reading and that is not supposed to happen. I am a ...
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2answers
419 views

Effect of salt bridge on Nernst potential

I learned 2 things: A salt bridge is necessary in a galvanic cell so charge does not build up in the halfcells countering the potential difference created by the separate redox pairs. Indeed, this ...
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1answer
860 views

Extraction of metals using electrolysis

I came across a question that goes as: The electrolytic method of reduction is employed for the preparation of metals that are: Less electropositive Moderately electropositive Highly electropositive ...
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1answer
1k views

How to state something as strong or weak oxidising agents?

It is said that conc. $\ce{H2SO4}$ is a strong oxidising agent. Why is it regarded as strong? In case of acids, we say something that fully ionizes in an aqueous solution is a strong acid. But what ...
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1answer
61 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
56 views

Can the electrochemical stability of a aqueous KOH solution be increased by adding more KOH?

My goal is to increase the efficiency of a nickel-iron battery. One of the options to reach this goal is:suppressing the hydrogen production. Due to electrolysis, the electrolyt will start ...
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2answers
335 views

Copper anode dissolves in electrolysis of copper sulfate solution [closed]

I did an experiment with copper sulfate where you place two copper rods in an aqueous solution of copper sulfate. You apply an electric current and copper metal builds up on the cathode. I noticed ...
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2answers
586 views

How do ions conduct electricity? [closed]

I mean to ask what do ions actually do while conducting electricity? Do they simply take up the electrons and transport it? If it is so, I do not understand how anions can take up more electrons if ...
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2answers
99 views

What are possible anode materials for copper(II) sulfate electrolysis?

I'm a student doing a research paper about copper sulfate electrolysis with an experiment by varying anode material, and aside from Pb and graphite (and pure Ti which I think wouldn't work without ...
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1answer
44 views

How ro interpret the given cell representation? [closed]

I have encountered cell emf having a reactant and product in the subscript. But this is the first timeI have witnessed 3 elements/compounds/ ions. How do i interpret this and what would be the ...
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1answer
2k views

Effect of resistance (distance) on the voltage of a galvanic cell [closed]

I'm doing an experiment at school on the rate of reaction in galvanic cell so I wanted to question how the length of wires and the addition of different resistors could affect the rate of reaction. I'...
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1answer
58 views

Energy level of the product in a cell reaction

I'm very new to chemistry, so please try to be as plain as possible with your answers. I'm studying the chemistry of alkaline cells: The cell I'm interested in has the following chemical reactions ...
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1answer
1k views

Why is the maximum work done by a voltaic cell negative [closed]

The maximum work done by a voltaic cell is given by -nFE. Why the negative sign? From what I know, a battery does positive work on the load attached to it
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515 views

Disproportionation Reaction [closed]

This is the problem I am trying to balance for redox: $$\ce{HXeO4 -> XeO6^{4-} + Xe + O2}$$ It is supposed to be in a basic solution. However, my answer does not contain $\ce{OH-}$ on either side:...
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1answer
70 views

Corrosion rate of a metal in a liquid in relation to the size of electric current

I am trying to determine the formula for calculating the corrosion rate of a metal in a liquid in relation to the size of electric current that is passed between 2 metal plates. For example: we have 2 ...
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1answer
656 views

What is the difference between these two Electrochemical cell

can someone please tell me the difference between the 1st and 4th electrochemical cell in the picture, I understand that in the 4th cell Cu is 0.1M so does that make it nonspontaneous and would the ...
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824 views

How do you calculate the power (in watts) required per mole of product for or an electrochemical reduction?

Is it the transfer current density of the product multiplied by the overpotential?
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1answer
2k views

Is Q in the Nernst equation [Reduction]/[Oxidation] or [Oxidation]/[Reduction]?

The Nernst equation is given by : $$E_{\text{cell}} = E_0 – \frac{RT}{nF}\ln{Q}$$ I have seen ${Q}$ given as both ${[\text{oxidation}]/[\text{reduction}]}$ and ${[\text{reduction}]/[\text{oxidation}...
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How to use the Nernst Equation

So I understand the Nernst Equation, but I don't have some info. (Please bear with me, I'm in secondary.) I'm doing a Cu - Al cell. My E cell is negative (-1.33). Does this have an affect on the ...
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2answers
84 views

Can iron oxide in well-point water be removed by electrolysis? [closed]

Can iron oxide dissolved in well point water stored in a 1000l plastic tank be removed by using a 12V battery charger and simple electrodes? If so what material should the electrodes consist of?
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108 views

Redox and anode/cathode in lead acid battery

I have watch a video about lead acid battery and I am very confused about the way the half reactions are labelled. I have learned that oxydation is the loss of electron (so it's the half reaction with ...
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2answers
56 views

How does a battery create a potential differece (voltage)? [closed]

I'm 15 and recently started electronics and I just had a question about batteries. (I've been told by people on physics stack exchange to come here to have my question answered). From what I ...
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1answer
56 views

What is the effect of putting salt on water during electrolysis [closed]

I want to decompose $\ce{H}$ ion and $\ce{O}$ ion by putting carbon electrode in the water, but it look so slow. What if I put sodium chloride? Would putting $\ce{NaCl}$ have effect on output gas($\ce{...
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1answer
231 views

Would a voltaic cell still work if you replaced both the cathode and anode with a carbon/graphite electrode?

for example, in this cell: Zn(s)|Zn2+(aq)||Ag+(aq)|Ag(s) if you replace the silver cathode with a carbon electrode, i know it would still transfer electrons, but if you also replaced the Zinc ...
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1answer
109 views

How could burying a copper and zinc plate underground connected by a surface wire (earth-based Galvanic cell) promote crop growth?

Background: To quote a source: In the 1840s, W. Ross of New York reportedly obtained a severalfold increase in the yield of a field of potatoes when he buried a copper plate (5 ft x 14 ft) in the ...
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1answer
211 views

How does the charge imbalance affect the cell reaction when there is no salt bridge in a galvanic cell?

As mentioned in the answers to this question Why is it important to use a salt bridge in a voltaic cell? Can a wire be used? a salt bridge is used to keep the two half cells neutral. i understand how ...
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60 views

Why can't two 3° free radicals combine?

In Kolbe Electrolysis, my teacher told that when a 1° or 2° free radical is used, we get alkanes through dimerisation. Why wont dimerisation occur for a 3° one??
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62 views

Why is the ionic product of water $K_w$ the same in acid, water, and alkali?

Seen on the web: The concentration of [H+] and [OH−] both vary based on the the composition (acid/alkaline) of the solution, but the remarkable thing is that their product does not. When [H+] goes ...
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1answer
130 views

Copper (II) Acetate from 5% vinegar + salt, electrochemically

I'm trying to create Copper (II) Acetate crystals, but in these times of Coronavirus it's difficult to come by hydrogen peroxide. I could be patient, but I'm not, so I'm trying to make it ...
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1answer
74 views

Most understandable notation for reduction and oxidation potentials

Nowadays a lot of electrochemistry is done using just electrode potentials (i.e. reduction potentials), so if in doubt the notation $E^o$ tends to imply a reduction potential. However, some chemists ...
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119 views

Since a Voltmeter does not account for the internal resistance of a voltaic cell, how can the actual EMF of the cell be measured?

Since a voltaic cell has some internal resistance the voltage measured by the voltmeter connecting the electrodes, is actually lower than the emf of the cell, so how can I measure the EMF of the cell ...
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1answer
146 views

Electrolysis of molten sodium chloride [closed]

Can somebody explain me the electrolysis of molten $\ce{NaCl}$ via electrode potential? Reduction potential of $\ce{Cl-}$ is -1.36 V, while sodium metal is -2.76 V, but still sodium is reduced and ...
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1answer
103 views

What do electrons usually do when lead acid battery is idle?

Lead acid batteries operation are governed by Redox reactions for charging and discharging. But, what do electrons usually do when lead acid battery is idle? And why? Assumptions: Say more ...
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1answer
45 views

Is the Gibbs energy of bulk metals in a Daniell cell affected by temperature? [closed]

From literature values, it is implied that the change in Gibbs energy of a Cu-Zn voltaic cell is largely due to the difference in Gibbs energy of the bulk metals (solid Cu and solid Zn). Does ...
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1answer
6k views

Does the concentration affect the voltage in electrochemistry?

For my electrochemistry lab I'm using $\pu{10 mL}$ of $\ce{ZnSO4}$ and $\pu{10 mL}$ of $\ce{CuSO4}$ solutions connected with a salt bridge. I connect $\ce{Zn}$ metal and $\ce{Cu}$ metal to a voltmeter ...
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1answer
86 views

Redox - concentration cell

I'm studying galvanic cells and I've found a demonstration that lead me to an impossible result, so there must be a mistake, but I can't find what it is. My problem is about concentration cells made ...