Questions tagged [reduction-potential]

For questions about the reduction potential (A measure of the tendency of a chemical species to acquire electrons and thereby be reduced) or its applications. Also see the tag [electrochemistry].

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Relative stability of $\ce{V^2+}$ and $\ce{V^3+}$ and their Standard Electrode Potential

My book - NCERT Chemistry for Class XII -Page 218 Contains the following paragraph: Initially they mention that the Low value for Standard Electrode Potential of $\ce{Sc^3+/Sc^2+}$ is due to the ...
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what are the differences between reversible cells and rechargeable cells?

My chemistry textbook says daniel cells are reversible, but not rechargeable. Why is it that all reversible cells are not rechargeable? Are all rechargeable cells reversible? why/why not?
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Is there any Iron solution that can reduce to Iron metal upon heating etc?

The chemical should be water soluble and then should reduce to form Iron metal when heated up or upon adding some other chemical etc. The final product does not need to be solid metal, it can be in ...
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2 votes
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Standard Hydrogen Electrode Assignment

How did scientists decide that 0V is the Standard Hydrogen Electrode? Was 0V measured through experimentation or was it decided in a meeting/convention? I am a little confused by the cited texts below....
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1 answer
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Reducing sugars and redox potential

I am wondering if reducing sugars are those that can act as reducing agents, and they act as such with Tollens and Fehling reaction, then what's the redox potential here? And is it a reversible ...
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Lithium Air vs Li Fluoride battery capacity [closed]

Lithium air aka lithium oxygen batteries are described as highest theoretical capacity battery possible. In wikipedia, it says lithium air has energy density 5210 Watt hour per kg, including weight of ...
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Clarification on standard hydrogen electrode diagram

When looking at standard hydrogen potential electrode diagrams in the case of a negative standard reduction potential for the other half cell, I came across one part that does not make sense to me: (...
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does entropy of half cell reaction change with stoichiometry [duplicate]

the standard potential of the following cell is 0.23V at 288K and 0.21V at 308K. Pt|H2|HCl(aq)||AgCl|Ag calculate $\Delta{S}$ . I know that $\Delta{S}=nF(\frac{\Delta{E}}{\Delta{T}})$ here n is the ...
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Is hydrogen peroxide a better oxidizing agent than chlorine gas? [closed]

If we compare the standard reduction potentials of $\ce{H_2O_2}$ with that of $\ce{Cl_2}$: $\ce{H_2O_2 + 2H^+ + 2e^- <=> 2H_2O : E^o = 1.78V}$ $\ce{Cl_2 + 2e^- <=> 2Cl^- : E^o = 1.36V}$ (...
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2 votes
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Oxidizing properties of sulfuric acid: can it oxidize hydrochloric acid to chlorine?

Can $\ce{H2SO4}$ oxidize $\ce{HCl}$ to $\ce{Cl2}$? I know that $\ce{KMnO4}$ can do it, but my question is considering $\ce{H2SO4}$. In sulfuric acid, sulphur is in +6 oxidation state and in $\ce{KMnO4}...
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How to write the Nernst Equation for this reaction?

I am required to write the Nernst equation for the following reaction: $\ce{O_2 + 4H^+ + 4e^- -> 2H_2O}$ Clearly, here $\ce{O_2}$ is getting reduced from an oxidation number of zero to an ...
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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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Is it the solution energy or the reduction potentials (or both) that drives a galvanic cell?

I have received conflicting explanations for why the redox reaction in a galvanic cell occurs. Explanation 1: Some say that it occurs because the anodic metal dissolves more easily than the cathodic ...
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Reaction of Copper and concentrated sulphuric acid

We know that dilute $\ce{ H2SO4}$ doesn't react with copper because copper has higher reduction potential ($0.33$) as compared to hydrogen ($0.00$). However, it reacts with conc. $\ce{H2SO4}$ and ...
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3 votes
3 answers
227 views

Does a change in oxidation number in a redox reaction mean that an actual electron transfer occured?

Oxidation numbers are fictitious charges that pretend the entire molecule is an ion i.e. it artificially localizes electrons onto atoms within a single molecule. In a redox reaction, we find that an ...
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How to use anodic and cathodic overpotentials to calculate electrolytic energy efficiency?

I am trying to calculate the energy efficiency for $\ce{CO2}$ reduction to formate, coupled to water oxidation based on literature data. $$\ce{CO2 + 2e- + 2H+ -> HCOOH}$$ $$\ce{H2O -> 2H+ + 1/...
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How can I convert cathodic energy efficiency to overall energy efficiency?

Im working on calculation which involve the energy efficiency of producing formate by CO2 electroreduction. I wonder how to convert the reported cathodic energy efficiency (71%) of papers e.g (1) this ...
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How to calculate Energy Efficiency of electrochemical production

I'm trying to understand some basic electrochemistry as a non chemist and struggling to find the info online effectively. Its clear that energy efficiency = Energy(useful) / Energy (input). So, I know ...
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Understanding Pourbaix diagram

I am recently taking courses in environmental chemistry and I was introduced to Pourbaix diagram. I was taught that the lines in the Pourbaix diagrams are equilibrium lines. Lets take as an example ...
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Can water oxidize zinc?

According to this textbook, H₂O has lower reduction potential (-0.83 V) than Zn (-0.76 V). This mean zinc is unable to reduce water to hydroxide. If so, why this video demonstrate that by heating zinc ...
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1 answer
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Electrochemistry - reduction potentials - an IB Chemistry Question [closed]

I have re-read the Electrochemistry chapter from my textbook just now to remind my self of the exact formulae. I still don't understand how to approach this question, however - how can we work it out? ...
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Could Carbon Monoxide be reduced by oxidising a more reactive metal?

After studying displacement at school, I wondered if it is possible to reduce the toxic gas of carbon monoxide to less harmful and more useful substances, like so: Carbon monoxide + metal -> Carbon ...
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3 votes
1 answer
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calculate cell potential for the voltaic cell where its involving the two cobalt species with Copper

Calculate the cell potential for the voltaic cell that results when the following two half-cells are connected at $\pu{25 ^\circ C}$: (1) A platinum electrode inserted into a solution of $\pu{0.10 M}$ ...
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Origin of electrode potential and its connection with electric double layer

Recently, I was learning about electrode processes and I came across the topic of "electrode potentials". I understood that at equilibrium, a potential difference was generated at the ...
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2 votes
1 answer
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Do I have to systematically show the protons in my reaction equation to find the Pourbaix diagram's line equations?

I was trying to get the line equation for the Pourbaix diagram for the couple $\ce{Ni(OH)2}/\ce{Ni}.$ I can write two chemical equations for basic and acidic conditions, respectively: $$ \begin{align} ...
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0 votes
1 answer
531 views

EMF - Intensive or Extensive Property

In electrochemistry, I know that standard emf of a cell (also called standard electrode potential (E°)) is an intensive property. But, I wanted to know whether non-standard emf will also be intensive ...
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3 votes
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Why do nitrogen-containing organic compounds give N2 as the combustion product?

My teacher gave the explanation stating that consider that first the nitrogen in lower state is oxidised to $\ce{N2}$ and then the further oxidation would stop as the $\ce{N-N}$ bond energy of $\ce{N2}...
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2 votes
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What does the salt actually do during electrolysis?

Pure water does not conduct electricity. When you dissolve a salt like $\ce{Na2SO4}$ in water the solution becomes a better conductor. If electrolysis is done on this solution, oxygen and hydrogen ...
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Nernst equations for the reduction of sulfate(IV) and nitrate(V) anions

Write a Nernst equation $(\pu{25 °C})$ for system: $$\ce{SO3^2- + 3 H2O + 6 e- -> S^2- + 6 OH-}\tag{R1}$$ and system: $$\ce{NO3- + 3 H+ + 2 e- -> HNO2 + H2O}\tag{R2}$$ I am not really sure if ...
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6 votes
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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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7 votes
2 answers
406 views

How to refine manganese metal from manganese(IV) oxide found in batteries? [closed]

I opened up some lantern batteries, and inside there's $\ce{MnO2}$ powder, carbon rods, and zinc casings, and other stuff that I don't know what it is exactly. I scraped out $\ce{MnO2}$-containing ...
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1 vote
2 answers
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Why can't nitrate ion in aluminium nitrate solution oxidise copper when a copper spoon is used to stir the solution?

I have been recently studying electrochemistry and I came across the electrochemical series. A question was asked saying what will happen if a copper spoon is used to stir an aluminium nitrate ...
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2 votes
1 answer
293 views

Are the potentials of the electrolytes equal in Galvanic cell?

My book defines Electrode Potential for a Galvanic Cell as follows: A potential difference that develops between the electrode and the electrolyte is called Electrode Potential $$E= V_{electrode} - ...
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1 vote
1 answer
277 views

Why can't iodide be oxidised to iodate in acidic medium?

Even if we use a strong oxidising agent like 'permanganate ion in acidic medium' it doesn't help oxidise iodide to iodate, but a relatively weaker oxidising agent 'permanganate ion in alkaline medium' ...
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6 votes
3 answers
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Can carbon dioxide be reduced to carbon monoxide and oxygen to produce energy?

There are lots of questions about reducing or burning CO2 to carbon and oxygen to solve climate change, but of course that wouldn't work because it takes a lot of energy. But carbon monoxide is more ...
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Reduction by Activated Carbon

Does reduction by carbon itself occur when filtration is performed using activated carbon? Is it part of the central mechanisms involved in activated carbon filtration? One of the specificities of all ...
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0 answers
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Correlation between redox pseudocapacitance, surface area, and cell potential with metal oxide electrodes

I'm having difficulty intuitively reconciling two different ideas concerning metal oxide thin films in contact with aqueous solutions: 1) that charge storage by both redox pseudocapacitance and ...
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3 votes
2 answers
440 views

Disproportionation of silver(I) in aqueous solution

Use the following equations to predict whether or not $\ce{Ag+}$ ions will disproportionate in solution: $$ \begin{align} \ce{Ag+(aq) + e- &-> Ag} &\qquad E^\circ = \pu{+0.80 V}\\ \ce{Ag^2+(...
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-1 votes
1 answer
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Metal deposition on passing electricity [closed]

A question asks about the results on electrolysis involving metals, and the answer says that Mg and Al would be deposited on the cathode. Aren't their reduction potentials lower than that of water? ...
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1 vote
1 answer
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What is the number of electrons being transferred in electrolysis of aluminum oxide? [closed]

$$\ce{ 2/3 Al2O3 -> 4/3 Al +O2}$$ As we know, to find the Gibbs free energy, we need to use this formula: $$ G= -nFE^\circ$$ What would $n$ be in this case? After breaking it down into the half ...
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2 answers
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Is HBrO2 a reductor?

I'm working on a chemistry project and that features a reaction where $\ce{Br-}$ participates in a redox reaction as a reductor. Eventually, $\ce{HBrO2}$ competes with $\ce{Br-}$ to react with the ...
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4 votes
2 answers
2k views

How does overvoltage affect the products of electrolysis?

When you electrolyse an aqueous solution of $\ce{NaCl},$ the product formed at cathode is $\ce{H2}$ gas (preferential discharging), but the product formed at anode is $\ce{Cl2}$ gas. According to ...
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What happens when a piece of copper is placed in 1M HCl?

I know that the answer is that nothing happens, but the explanation is confusing me in some places. Firstly, we are given that: \begin{align} \ce{Cl2 + 2e- &-> 2Cl-} & (E &= \pu{1.36 V})...
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0 votes
1 answer
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How do you work out whether reduction would occur based on reduction potentials [closed]

I'm having a bit of trouble with standard reduction potentials. Specifically, when you're given a table of half reactions and reduction potentials...is the potential of the reverse reaction (the ...
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1 answer
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Nernst equation and equilibrium

I am currently stuyding electrochemistry, and recently I've stumbled upon a problem where one is supposed to calculate the concentration of Fe3+ ions after a solution containing Fe2+ was titrated ...
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Log(Q) is zero, therefore the effect of temperature change is unaccounted for by Nernst Equation?

I have an internal assessment on Nernst Equation. The experiment is seeing how changing temperature effects cell potential. The solution are zinc and copper sulfate with each having concentration of ...
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4 votes
1 answer
450 views

Subtracting standard electrode potentials

As far as I'm aware, if we construct a half cell ($\ce{A + e- <=> A-}$) under standard conditions then the standard electrode potential $E^⦵$ is the potential of the $A/A^{+}$ couple wrt. SHE, ...
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1 answer
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Effect of reduction potential on particle size of chemically precipitated silver particles [duplicate]

Is there no mathematical relationship between redox potential and particle size saying that an $X$ potential should yield a $Y$ particle size? Right now its general that large redox potential results ...
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Can the 5+ and 4+ oxidation state of Vanadium ion exist independently?

From my class text book: The oxidation states of Vanadium ions 5+ and 4+ are shown in the compounds $\ce{VO2^{+}}$ and $\ce{VO^{2+}}$ respectively, whereas $\ce{V^{3+}}$ and $\ce{V^{2+}}$ are ...
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1 vote
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Stability of cuprous iodide in aqueous solution

An aqueous solution of $\ce{Cu+}$ is usually unstable, but $\ce{CuI}$ is stable. Explain. $E^\circ(\ce{Cu^2+/Cu+}) = \pu{0.153 V}$ and $E^\circ(\ce{Cu+/Cu}) = \pu{0.521 V}.$ I found this question ...
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