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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Why is the water reduction of oxygen favored in acidic conditions?
The standard reduction potential of diatomic oxygen in acidic conditions is +1.23 volts. However, the standard reduction potential of diatomic oxygen in basic conditions is only +0.40 volts.
Why is ...
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What is an efficient way to generate CO2 electrochemically?
I would like to build a small carbon dioxide generator for experimental purposes. There are two requirements that are set in stone:
It has to be electrochemical. (Easy to switch on/off with ...
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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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Protons and osmotic potential
In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?
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Will a film of oil on water retard evaporation (of water) and prevent air and atmospheric impurities from diffusing into it?
I vaguely recall hearing that a layer of oil on water will slow down the evaporation of water, as well as serving as a barrier that would prevent (or retard) the diffusion of air and atmospheric ...
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Does conductivity change in a solution due to rust?
I plan on conducting an experiment in which I place an iron nail in water and analyze its rate of corrosion into rust with different concentrations of NaCl.
My original plan was to cover the water in ...
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How are the chemical reactions of the table of standard reduction potentials experimentally determined?
My background: I've read several books and articles on electrochemistry and even do photoelectrochemical research in a lab, so I'm somewhat familiar with the concepts and techniques.
In texts on ...
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Corrosion of a galvanic couple made with silver and gold
If a bangle is made out of gold and silver, connected with each-other would there be corrosion happening?
If so, can it be explained using the galvanic series?
Also do those metals undergo oxidation ...
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Is possible to figure out if a battery is NiCd or NiMH?
Aside from opening it of course. I'm not sure if this is the right place to ask this but I have a rechargeable battery pack for an Xbox One controller and the info on it says that it's a sealed nickel ...
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Nernst equation and electrolysis
Let's say we have a stable solution of
$\mathrm{A}_{\left(\mathrm{aq}\right)}^{2+}$
and $\mathrm{C}_{\left(\mathrm{aq}\right)}^{+}$
, with their respective counter-ions.
The associated redox ...
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What is the role of hydrochloric acid in a copper electroplating bath?
Considering water as a given, the third most important ingredient in a copper electroplating solution, as a short survey of related recipe webpages will show you, is hydrochloric acid (HCl). Here's a ...
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Clarifications on thermodynamic cell efficiency
The thermodynamic efficiency of any cell (especially Fuel cells) is given as $$\frac{\Delta G}{\Delta H} \times 100$$
I understood this partly, that since $\Delta G$ is the useful work obtained in ...
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Correct Definition of Absolute Electrode Potential
I thought absolute electrode potential is Galvani potential difference at the interface. However, it is given by following equation in John Bockris - Modern Electrochemistry (Ref.1): $$ E^M \mathrm{(...
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Need for bubbling hydrogen gas as part of hydrogen electrode
Why the hydrogen gas should be bubbled continuously through the electrolyte in a hydrogen electrode?
To keep the solution saturated with hydrogen gas
To clear the platinum electrode
To ...
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Why isn't my electrochemical cell producing its potential voltage
For a school project, I am testing how concentration affects the voltage output of three metals. So I am building voltaic cells with 0.1 M copper nitrate and 0.1 M, 0.01 M, and 0.001 M of zinc, ...
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Copper layer doesn't stick after Copper electroplating
I am playing around with copper plating using Copper Sulfate solution with electricity.
I am using 2-2.5 volts as power source and around 100-500 mA.
It is actually a very small container around 100 ...
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Explanation for a basic decomposition of water experiment
My son is trying to write a conclusion for a basic decomposition of water experiment using a 9 V battery (with a test tube placed over each terminal) placed inside a salt water solution. The results ...
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Is a strontium–fluorine battery the highest voltage battery using pure elements?
Strontium has a very low standard electrode potential and fluorine has a very high one.
\begin{align}
\ce{F2 + 2e^- &<=> 2F^-} &\quad E^\circ &= \pu{+2.87 V} \tag{R1} \\
\ce{Sr &&...
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Delta G for Standard Hydrogen Electrode reaction
I’m dealing with electrochemistry problems.
For the following reaction
$$\ce{2H+ +2e- <=>H2}\quad E^\circ=0\ \mathrm{V}$$
Does it make sense to say
$$\Delta G^\circ=-nFE^\circ=0$$
Which would ...
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Copper electrode in a Daniel cell
Suppose I have a beaker containing $\ce{CuSO4}$ solution and I dip $\ce{Cu}$ rod in it. What reactions are going to take place? Is the $\ce{Cu}$ rod going to acquire any positive charge?
I am asking ...
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Electrolysis of molten nitrates, sulphates and carbonates
We know that nitrates, sulfates and carbonates doesn't or hardly oxidized by anode in the ...
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How to find the band gap for a compound?
I have processed a si/polymer hybrid using a silane coupling agent which I need to determine the energy gap / band gap. Would you please let me know the procedure to go about determining the band gap?...
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Correct equation for Ionic Conductivity (λ) in Solutions?
We haven't started on Electrochemistry at school yet, but I did manage to find some time to read up on the topic. One thing I've noticed from when I started, is that different books and sites use ...
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Why is neutrality so important in a voltaic cell? [closed]
I'm having trouble understanding the purpose of a salt bridge in a voltaic cell. I keep reading the same thing: without a salt bridge/porous cup, the anode will continue to lose mass and become ...
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Could a lead-acid battery electrolyte be replaced by hydrochloric or nitric acid?
Hydrochloric acid, as well as nitric acid, are also strong acids like sulfuric acid. So, why are not they used commercially in lead-acid batteries?
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How can I produce hydrogen gas efficiently and cheaply?
I have been intrigued by one of the principles of chemistry lately- electrolysis. In my knowledge, electrolysis is a quite dangerous operation as the decomposition of water produces hydrogen and ...
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Explanation for the reactions in a saltwater battery with zinc and copper electrodes
I am a physicist, not a chemist. I'm trying to get a basic understanding of the reactions taking place in a battery using a saltwater electrolyte with copper and zinc terminals. I'm writing a general ...
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Why are electrolysis cell plates turning a brown color?
I have been experimenting with electrolysis for producing oxyhydrogen and using potassium carbonate $(\ce{K2CO3})$ as an electrolyte. After several hours of electrolysis, I noticed that the plates ...
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Why can't a primary cell be recharged?
The explanation I have found is that primary cells have irreversible reactions, so passing current in the opposite direction cannot recharge the cell. But as far as I understood it, no reaction is ...
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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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What would the maximum energy density of a power source based on carbon-14
Various ways of generating electricity from small radioactive power sources have been long known.
The Voyager space probes launched in the 1970s use thermoelectric generation from plutonium sources to ...
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Why is mass gained at the cathode?
I'm dealing with a voltaic cell constructed like this:
(From “Electrochemistry”, chapter 19 from the book Principles of General Chemistry (v. 1.0).)
I understand that as oxidation occurs at the $\...
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How to determine the potential of a cadmium zinc cell under standard conditions?
I write the half-equations:
\begin{align}
\ce{Zn &<=> Zn^2+ + 2e^-}& E^\circ &= +0.763~\pu{V}\\
\ce{Cd^2+ + 2e- &<=> Cd}& E^\circ &= +0.403~\pu{V}
\end{align}
In ...
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Lemon Battery works on water?
My son and I were using a mini science experiment kit for creating batteries with copper, zinc, and lemonade, similar to the famous lemon battery project. My son's hypothesis was that the liquid had ...
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In a simple chemical cell
Why do the electrons, arising from the oxidation of the anode, flow through an external circuit? Why does it not just flow through the electrolyte and reduce the cathode? Why do the electrons give the ...
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Will oxidation/reduction of copper still occur in an electrochemical cell if it is not in an aqueous environment?
Notation of the reduction and oxidation of copper typically includes the aqueous state. Illustrated below:
$$\ce{Cu(s) -> Cu^2+(aq) + 2e-}$$
This event usually occurs at 0.34 V. What if the copper ...
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Galvanic cell involving a hydrogen electrode and copper electrode in sodium hydroxide
A galvanic cell consists of a standard hydrogen electrode and a copper
electrode. Suppose that the copper electrode is immersed in a
solution that is $0.100\ \mathrm{M}$ in $\ce{NaOH}$ and that ...
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Formation of species in electrolysis
I understand the principles of electrolysis of salts in aqueous solutions, but there are two points on which i am unsure.
At the positive electrode, how can you work out which ions will ...
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Why can some redox half-reactions be combined and some cannot? [duplicate]
I mean by "combining" is to make a new half-reaction equation and not an overall equation for a reaction in whole.
For instance, I was trying to arrive at the following half-reaction:
$\ce{MnO2(s) + ...
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In a galvanic cell, why does an electrode with a higher potential "pull" the electrons from the electrode with a lower potential?
I'm doing Grade 12 Chemistry and I'm unsure of this, taking the hydrogen electorde as having a potential of 0 volts.
I'll use the copper-zinc cell as an example. Just let me know if I've got the full ...
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Express the maximum work from a voltaic cell
The net cell reaction of an electrochemical cell and its standard potential is given below:
$$\ce{ Mg + 2Ag+ ->Mg^{2+} + 2Ag} \ \ \ \ \ \ \ \ E^\circ=3.17\:\mathrm{V}$$
The question is to find the ...
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How do you measure an element’s electric charge?
I was reading about the history of the periodic table and the description of an element’s atomic number as its proton number. I couldn’t find the source again but it was stated that they figured out ...
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Why is the reduction potential of Cu$^{2+}$ less than Cu$^+$?
The reduction potential is the electrical potential of the species to be reduced. It's basically how positive it is (compared to a reference, since voltages are relative).
Tables list the following
$$\...
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Finding EMF of a galvanic cell without standard potentials
For the galvanic cell
$$\ce{Ag | AgCl(s), KCl (\pu{0.2 M}) || KBr (\pu{0.001 M}), AgBr(s) | Ag}$$
find the EMF generated given $K_\mathrm{sp}(\ce{AgCl}) = \pu{2.8e-10},$ $K_\mathrm{sp}(\ce{AgBr}) = \...
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Redox potential of a lead–acid battery
In the German Wikipedia there are two reactions on the poles of the battery shown with the following potentials:
$$
\begin{align}
\ce{Pb + SO4^2- &-> PbSO4 + 2 e-} &|\pu{-0.36 V}\\
\ce{...
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Decreasing magnitude of peaks in cyclic voltammogram?
I'm in an instrumentation course and we covered cyclic voltammetry earlier in the semester and will be doing an experiment in CV next week.
My question is this:
If you have a reaction and sweep the ...
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How would using different salts in a salt bridge effect the voltage generated by a voltaic cell?
If I use a range of different nitrate solutions (e.g. calcium nitrate, iron nitrate) for the salt bridge in a voltaic cell, what effect would it have on the flow of ions in the voltaic cells?
Will ...
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Negative potential of the oxidation of iron(II) to iron(III)
The oxidation potential which I found on the internet the following reaction
$$\ce{Fe^{2+} -> Fe^{3+} + e^-}$$
is $\pu{-0.77 V}$. But how can it be negative? Negative oxidation potential means ...
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Unknown white precipitate in electrolysis of water
I was electrolysing water using a copper anode and zinc cathode. The water was from the tap and where I live is very hard. I was using about 20V between the two electrodes. As I applied the voltage,...
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How can Nernst equation apply in this redox reaction?
$$\ce{CuSO4 + Zn -> ZnSO4 + Cu}$$
What is the cell potential of the voltaic cell with copper and zinc electrodes if the system is at 50 degrees and the solutions are both at 1 mol? How can it be ...
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