Questions tagged [redox]
Redox is the portmanteau of reduction and oxidation. This tag should be used in questions where both the reduction and the oxidation process are under focus. This tag is not limited to inorganic chemistry. If the question is specifically about either reduction or oxidation (not both) of an organic compound, use [organic-reduction] or [organic-oxidation] instead.
1,447
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Voltaic cell equilibrium confusion
In a voltaic cell, taking one with $\ce{Zn}$ and $\ce{Cu }$ electrodes for an example, an EMF is formed because the equilibria at the $\ce{Zn}$ electrode is shifted more towards the $\ce{Zn^2+ + 2e-}$ ...
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How is MnS + 2HCl -> MnCl2 + H2S a redox reaction, in terms of electron transfer?
$$\ce{MnS + 2HCl -> MnCl2 + H2S}$$
If oxidation and reduction is taken to be the loss of hydrogen and the gain of hydrogen respectively, then I can see how the aforementioned reaction is redox — $\...
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Incompatibility of Helmholtz Double Layer and Redox electrochemistry
In an electric double layer capacitor(EDLC) (or any situation with a Helmholtz double layer) what prevents the ions from being reduced or oxidized like the ions in an electrochemical cell?
If it is ...
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Simultaneous electrolysis on applying a suitable amount of potential difference
This question was asked in the JEE in 2020:
$\pu{250 mL}$ of a waste solution obtained from the workshop of a goldsmith contains $\pu{0.1 M}$ $\ce{AgNO3}$ and $\pu{0.1 M}$ $\ce{AuCl}.$ The solution ...
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3
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Do molecules containing enough oxygen to burn themselves exist?
Is there a molecule with enough oxygen in it (for example, something like $\ce{HCOOOH}$) such that it can undergo complete combustion without requiring any additional oxygen? For example the above ...
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327
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How does cyclopentadienyl anion act as reducing agent?
I am a second year university student, so I'm afraid my chemistry isn't great. I am looking for an explanation of how the $\ce{Cp-}$ anion acts as a reducing agent.
To contextualise - in a simple ...
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Balancing OH- reduction to H2 [closed]
I have to balance the following redox equation:
$\ce{B + NaOH -> NaBO2 + H2 + Na2O}$
Here I identified B as the species which undrgoes oxidation and wrote the oxidation half-reaction:
$\ce{4OH- + B ...
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Converting pyrite to iron sulfate
I was reading a Jules Verne book recently, in which the following chemical reaction was done:
He placed a layer of branches and chopped wood, on which were piled some pieces of shistose pyrites ... ...
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2
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Oxidation of sulfuric acid to Marshall's acid and its half cell reaction
$\ce{H2O2}$ can be prepared by successive reactions:
$\ce{2NH4HSO4 -> H2 + (NH4)2S2O8}$
$\ce{(NH4)2S2O8 + 2H2O -> 2NH4HSO4 + H2O2}$
The first reaction is an electrolytic reaction and second is ...
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3
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Can oxidation and reduction be described in terms of transfer of oxygen in the following way?
After reading and thinking about oxidation and reduction a bit, I tried to come up with a way to explain it to myself… Could someone verify if this is technically correct?
Consider 2 elements A and B ...
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446
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Can a salt bridge run out and become a regular bridge? [duplicate]
The goal of a salt bridge is to maintain electroneutrality in both of the half-cells.
At the anode half-cell, the anode is oxidized. The resulting electrons travel up the wire to the load while the ...
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Specifically how does the presence of moisture and oxygen affect the yield of ferrocene? [closed]
In a lab this week at uni we made ferrocene (I'm a second year Chemistry student). This was done by reacting nBuLi with cyclopentadiene (kept in freezer) to create the Cp anion in-situ.
To this ...
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What happens with electric charges in a salt water battery?
When building a simple salt water battery, consisting of a zinc-anode, copper-cathode and an NaCl-solution, I noticed the following:
When closing the circuit, the current decreases over time. (No ...
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Why do diluted sulfuric acid and hydrogen peroxide etch copper only when chloride ions are present?
I've mixed 30 ml 10% sulfuric acid with 20 ml 3% hydrogen peroxide and put a drop of this solution onto copper foil. The solution quickly removed the oxide layer from the copper but did not dissolve ...
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3
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How can one determine if a chemical reaction is impossible to balance?
I asked this question on Math Stackexchange, but thought I'd get a more chemical view:
https://math.stackexchange.com/questions/4326904/determining-whether-or-not-a-system-of-equations-has-nonzero-...
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2
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How to calculate/estimate the contamination rate of ultra pure water (UPW) in the presence of metals?
Metals are known to release ions into ultra pure water. Do any equations or empirical data sets exist for estimating the rate of contamination with different metals? I don't need a specific solution; ...
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Equilvalence point in redox Titration of Fe(II) and Fe(III) with Reinhardt-Zimmermann solution
In the lab at university, we need to conduct a simultaneous determination of iron(II) and iron (III) ions using potassium permanganate solution.
In the first step, we just fill up our given sample ...
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True or false: "A used AA battery contains fewer moles of electrons than a new AA battery."
I recently took a Gen. Chem. 2 exam that contained this question. I answered false, but my professor said the answer is true. My reasoning was that any electrons that leave the anode end up at the ...
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2
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The oxidation number of N and Cl in NOClO4
My doubt is not about the solution itself, actually I was able to find the solution myself.
We could split NOClO4 as (NO+) + (ClO4-) and then proceed, but here I "knew" this split. Is there ...
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2
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Why do we need salt in a salt water battery?
I am having problems understanding why we do need salt added to the water to make this shown galvanic cell work.
I understand that Zinc wants to dissolve into the electrolyte, resulting in $\ce{Zn^2+}$...
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2
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Balancing complex redox reaction in a basic solution [closed]
I'm incredibly lost right now. I understand fully how to balance redox reactions in acidic/basic solutions, but the problem my teacher posted is not letting me use the method taught to us. I've ...
3
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0
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282
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What reaction does happen when molten sodium hydroxide reacts with aluminium?
The reaction between aqueous sodium hydroxide and aluminium follows this equation:
$$\ce{2NaOH + 2H2O + 2Al = 2NaAlO2 + 3H2}$$
But it's obviously not possible to balance this equation without the ...
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151
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Why is comproportionation thermodynamically favoured for the synthesis of Mn(acac)3?
I'm currently learning about ligands in school and I'm wondering why does comproportionation happen in the overall equation? There are fewer chemical species on the product side and the entropy of the ...
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2
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162
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Where does the free electron from from in Ag/AgCl reaction?
For the Ag/AgCl half reaction, where did the free electron that AgCl captured come from? Did it come from the Ag wire? If so, why would Ag wire give an electron to AgCl, both atoms are Ag and have the ...
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1
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What role does ammonium play in the explosion of ammonium nitrate? [duplicate]
I read that ammonium is the "fuel" and nitrate is the "oxidizer". The nitrate oxidizes because it's a nitro group, but what's the mechanism of the ammonium?
3
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1
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Does this coupled reaction actually happen (decomposition of calcium carbonate)
I found the following example of a coupled reaction to drive the decomposition of calcium carbonate. I get the calculation part of it, that the changes in Gibbs energy sum to a negative amount. But ...
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Redox reaction of cycloheptatriene ligand
The reaction I really don't understand is the second one which produces the cycloheptatriene ring with a positive charge. The only thing I can think of is that the hydrogen is being ejected and ...
4
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1
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Why are holes appearing in this aluminum kitchen foil on my radiator?
I thought I would try to deal with dehumidified air from radiators by filling simple troughs of water placed on the top, which in theory would evaporate water as the radiator heated the air. I crafted ...
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What are compounds where oxygen has oxidation state -1/3 called?
I have heard of oxides, peroxides and superoxides where oxygen oxidation number is $-2, -1, -\frac{1}{2}$ respectively.
But I came across a molecule with the formula $\ce{KO_3}$, oxygen has $-\frac{1}{...
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How do I balance a hydrogen peroxide redox equation? [closed]
I have this equation:
$$\ce{H2O2 + MnO4- + H+ -> O2 + Mn^2+ + H2O}.$$
How do I balance it, since O has two different oxidation states on one side?
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2
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Effect of H+ concentration on equilibria
Considering the two equilibriums below, when the $[\ce{H+}]$ decreases, my book says that equilibrium \eqref{rxn:2} will shift to the left by a greater extent compared to equilibrium \eqref{rxn:1} ...
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Why does mercury(II) nitrate form only when using concentrated nitric acid?
In the reaction between mercury and nitric acid, mercury(II) nitrate only forms when concentrated nitric acid is heated up and added to it, if the acid is dilute, mercury(I) nitrate forms.
I ...
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Why sodium metabisulphite is not an oxidising agent? [closed]
We know that the maximum possible oxidation state of sulphur is $+6$. Whereas the oxidation states of sulphur in sodium metabisulphite are $+3$ and $+5$. Can't these oxidation states reduces to a ...
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Does boron exhibit +1 oxidation state?
My teacher told that boron exhibits only a $+3$ oxidation state, but he also wrote the unbalanced reaction
$$\ce{B + C -> B4C}.$$
Carbon has greater electronegativity than boron leaving us with $\...
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1
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How can I prevent and remove oxidation on the surface of liquid Galinstan?
The oxide layer formed on galinstan (or its component of pure gallium) when exposed to air increases wetting and dulls the appearance. Is there a clear liquid material in which a blob of liquid ...
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Can hydrogen peroxide dissolve rust?
WD-40's "help page" on "How To Loosen Rusty Bolts, Screws And Nuts" states:
Hydrogen peroxide can dissolve rust. Applying hydrogen peroxide to the
fasteners and letting it sit is ...
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1
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How to balance this half-equations [closed]
HNO$_3 \rightarrow $ N$_2$O(g)
I'm looking at the solution and it says that the above reaction can be modified as
NO$_3^-$(aq) $\rightarrow$ N$_2$O (g)
I don't understand why. Can someone please ...
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1
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Balancing redox reaction by removing spectator ion SO₄²¯ [closed]
I aimed to balance the equation
$$ \ce{Cr2O^{2-}_7 + FeSO4 + H+ -> Cr^{3+} + Fe2(SO4)3} $$
My teacher explained me that since $\ce{SO^{2-}_4}$ is the spectator ion, I must proceed in this equation ...
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1
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Fundamentally, what is the difference between redox and acid-base reactions?
For example, consider:
$$\ce{NH3 + H2O -> NH4+ + OH-}$$
Here, the $\ce{NH3}$ is acting as a base (By Lewis theory, it is an electron pair donor).
Why don't we consider this to be a redox (there is ...
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How do I balance redox equations with three reactants?
Could anybody please explain me the concept of balancing redox reactions with three reactants? Either some solving steps or even the solution would be very appreciated.
For example, I don't know how ...
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1
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Does nascent Oxygen/Hydrogen really exist or just or is it just electron from ionic equation? [duplicate]
Recently I was taught by my teacher that there is no such thing as nascent oxygen neither hydrogen. It just represents Electrons from ionic equations. Then he proceeds to give example of following ...
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1
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How to derive formulas for n factor of different types of reactions?
While studying Redox reaction, I came across this term called n-factor which seems to me as a short-cut trick to do the questions quickly. Since I am preparing for a competitive exam so our chemistry ...
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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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Electrode potential of Br2/HBr half cell
I am wondering if it is possible to find the electrode potential of such a half cell:
$$\ce{Br2 (l) + 2 e- <=> 2Br-(g)}$$
The standard electrode potential is for $\ce{Br-(aq)}.$ However, is it ...
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Oxygen-releasing material at ≤ 200 °C [closed]
I have to anneal a ceramic in high oxygen pressure, in an autoclave. For this purpose I need a chemical which can release oxygen at temperature less than or at 200 °C. Would appreciate any suggestion.
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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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Extraction of copper from chalcopyrite
During the extraction of copper from chalcopyrite ore, the ore ($\ce{Cu2S.Fe2S3}$) is heated to form $\ce{Cu2S}$ and $\ce{FeS}$. Then during smelting it reacts with $\ce{O2}$ to form $\ce{Cu2O}$.
Then ...
2
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0
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Do decomposition potentials change during electrolysis?
I was just wondering if decomposition potentials actually change during electrolysis. For example, if we reversed the Daniell cell reaction so that copper is oxidized, the half cell reactions would be:...
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Calculating Gibbs free energy change when the state of ions is unknown
Problem
Calculate $\Delta G^\circ$ for the following reaction:
$$\ce{Zn(s) + Ag2O(s) + H2O(l) -> Zn^{+2}(aq) + 2Ag(s) + 2OH-(aq)}$$
Given $E^\circ_{\ce{Ag+/Ag}} = \pu{0.80 V}$, $E^\circ_{\ce{Zn^{+...
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2
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What gives dilute/conc nitric acid/ conc sulfuric acid their oxidizing property?
I know that dilute sulfuric acid and very dilute nitric acid don't have any oxidizing tendency while dilute/conc $\ce{HNO3}$ and conc $\ce{H2SO4}$ do.
Why do these more concentrated acids have this ...
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