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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How does cell potential change with temperature for positive enthalpy and negative entropy?
A recent United States National Chemistry Olympiad question asked:
A certain voltaic cell has a standard cell potential that increases with increasing temperature. Which best explains this ...
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Fundamental understanding of electrode potentials
The electrical double layer, is commonly used to describe the origins of electric potentials that is fundamental to electrochemistry. This model is quite outdated from my understanding, but it is ...
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Deriving Nernst Equation for a hydrogen-oxygen Fuel cell
Reading across electrochemistry books (particularly the fuel cells chapter of the book "Alternative energy systems and applications" by Hodge) I came across the following formulae:
$$\Delta ...
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Using biochemical standard state versus chemical standard state
Can I use the table below to calculate the standard cell potential, $E^{\circ}$, of ethanol oxidation to acetaldehyde (EtOH + 1/2O2 $\rightarrow$ Acetaldehyde + H2O)? Does it matter that the half-...
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Does reduction occur well above the reduction potential?
I was reading the voltammetry section of Analytical Chemistry 2.1 (Harvey), and it says that for the reduction of $\ce{[Fe(CN)^{III}6]^3-}$ to $\ce{[Fe^{II}(CN)6]^4-}$, which has a standard reduction ...
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Why does metal atom get an effective potential difference in voltaic cells [closed]
Why is it that metal atoms , experience this potential difference when immersed only in their salt solutions. When they are in contact in real life we cannot see current conducting through it.
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what does the oxidation/reduction potential actually mean? [closed]
The standard potential of a species is actually its tendency to gain/lose electrons and get reduced/oxidized. But what I want to understand : 1- Is the standard potential an absolute quantity, or a ...
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Regarding the standard reduction potential and electrolyte/solid interface
I am modelling lithium-sulfur batteries ($\ce{LiS}$ batteries) and a strange phenomenom happens during charge, named infinite charging, which I show below:
The factor $f_\mathrm{C}$ that appears in ...
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Why is the reduction potential of Cu$^{2+}$ less than Cu$^+$?
The reduction potential is the electrical potential of the species to be reduced. It's basically how positive it is (compared to a reference, since voltages are relative).
Tables list the following
$$\...
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In a voltaic cell with standard hydrogen electrode is the measure half cell always the cathode?
I am a bit confused. My openstax textbook states:
"When the half-cell X is under standard-state conditions, its potential is the standard electrode potential, E°X. Since the definition of cell ...
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what are other metal oxide that can be used as electron acceptors?
I am using silver oxide as a cathode because it's common. I was reading that " some solid metal oxides (e.g., silver oxide, lead dioxide, and manganese dioxide) possess high redox potentials. ...
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Deriving reduction potential from redox reactions
From a past USNCO test:
40. What is the standard reduction potential of $\ce{Hg^2+(aq)}$ to $\ce{Hg(l)}$?
\begin{align}
\ce{2 Hg^2+(aq) + 2 e- &-> Hg2^2+(aq)} &\quad E^\circ &= \pu{+0....
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What parameters do you use to find the order in which elements will leave a solution during electrolysis?
I am looking to perform electrolysis on a molten solution of many elements, specifically a mix of iron, sodium, potassium, silicon, aluminum, and titanium oxides and chlorides. What I'm trying to ...
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Electrode potential and likeliness to reduce/oxidize (electrolysis) [closed]
I'm a little confused about situations where multiple chemical compounds can be reduced/oxidized and the likelihood of this happening to one compound over the others, depending on the electrode ...
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Why is there a discrepancy between predicted and nominal voltages of alkaline batteries?
According to Wikipedia, the sum of standard reduction potentials for the half reactions for alkaline battery yield $\pu{1.43 V}:$
$$\begin{align}
\ce{Zn(s) + 2 HO–(aq) &-> ZnO(s) + H2O(l) + 2 e–...
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Why does copper(II) sulfate react with potassium iodide in aqueous solution?
According to the list of standard reduction potentials [1, p. 5-79] $E^\circ(\ce{Cu^2+/Cu^+}) = \pu{+0.153 V},$ while $E^\circ(\ce{I2/I^-}) = \pu{+0.5355 V}.$ Doesn't it mean that iodine has more ...
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How to determine the cell potential of chromium(III) — permanganate cell?
Determine the cell potential of the following cell:
$$\ce{Pt | Cr^3+ (\pu{0.125 M}), Cr2O7^2- (\pu{0.200 M}), H+ (\pu{0.600 M}) || MnO4- (\pu{0.150 M}), Mn^2+ (\pu{0.400 M}), H+ (\pu{0.250 M}) | Pt}$$
...
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Cyclic voltammetry graph of graphite electrode in NaOH
I'm a student who is a beginner to cyclic voltammetry and university electrochemistry in general. For my lab experiment, I performed cyclic voltammetry on a graphite electrode in 1 M NaOH with Ag|AgCl ...
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Arranging the following elements in the increasing order of their oxidising power [closed]
I was given the following equations and asked to arrange them in increasing order of their oxidizing power:
$\ce{Co^{+3} + e- -> Co^{+2}}$ with an electrode potential of $+1.81\, \mathrm{V}$
$\ce{...
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Why is the standard electrode potential positive for half cells that are easily reduced?
I was studying electrochemistry from my school textbook.
The cell potential in the book is defined as the difference between the electrode potentials of the cathode and the anode.$$E_\text{cell}=E_\...
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Why do we sometimes change the sign for standard electrode potentials?
Question:
In this cell, the copper is oxidized and $E_{cell} = \pu{+1.15 V}$.
$$\begin{align}
\ce{Cu^2+(aq) + 2e− -> Cu(s)} & &(E &= \pu{+0.34 V})\\
\ce{Mn^3+(aq) + e− -> Mn^2+(aq)} ...
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Why chlorate(V) is one of the primary products of disproportionation reaction between chlorine gas and hot concentrated NaOH?
Cold diluted $\ce{NaOH}$ reacts with $\ce{Cl2}$ producing hypochlorite:
$$\ce{2 NaOH(aq, dil, cold) + Cl2(g) -> NaClO(aq) + NaCl(aq) + H2O(l)},\tag{R1}$$
whereas hot concentrated $\ce{NaOH}$ yields ...
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Electrolysis when E_cell = 0
I'm a bit confused by the electroplating of Zinc onto Copper, with Zinc (anode) and Copper (cathode) electrodes in a Zn(NO3)2 solution.
The reduction reaction is: Zn2+ + 2e- ---> Zn (s) (E_rxn = -0....
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Why is my battery of galvanic cells not enough to power a lamp rated for a lower voltage than the battery provides?
I made a series of 12 galvanic cells with saltwater as an electrolyte and zinc and copper as electrodes. It produces 8.8 V, but it can't even light a 2.5 V bulb (the bulb can be lit by a 1.5 V source)....
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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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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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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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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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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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Calculating the potential of iron–copper electrochemical cell with Nernst equation
Calculate the ${E_\mathrm{cell}}$ (not ${E^\circ})$ at $\pu{25 °C}.$
$$\ce{Cu(s) | Cu^2+ (\pu{0.10 M}) || Fe^2+ (\pu{0.0030 M}) | Fe(s)}$$
$$
\begin{align}
E^\circ(\ce{Cu^2+/Cu}) &= \pu{0.339 V} \\...
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How to use anodic and cathodic overpotentials to calculate electrolytic energy efficiency?
I am trying to calculate the energy efficiency for $\ce{CO2}$ reduction to formate, coupled to water oxidation based on literature data.
$$\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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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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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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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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