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.

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613 views

In a galvanic cell, why do electrons move through the wire from zinc to copper?

I understand that there is aqueous $\ce{Cu^2+}$ in this scenario which pulls on the electrons from the zinc causing the electrons to move through the wire, but how does the electronegativity of $\ce{...
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2answers
60 views

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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2answers
86 views

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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3answers
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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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0answers
27 views

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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Why does nitric acid react with less reactive metals [duplicate]

So we are studying the acid base chapter and I came across these reaction: $$\ce{3Ag + 4HNO3 -> 3AgNO3 + NO + 2H2O}$$ My question is, how can $\ce{Ag}$ react with $\ce{HNO3}$ as it is lower than ...
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86 views

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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2answers
205 views

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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2answers
379 views

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 ...
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3answers
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Sodium Polysulfide production from NaOH and Sulfur

Does the sulfur also oxidize the $\ce{OH-}$ radicals after the $\ce{Na2S4}$ chains form? Something like this: $$\ce{9S + 4NaOH -> 2Na2S4 + SO3 + H2O}$$
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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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1answer
142 views

Oxygen reduction - beginner level

I am embarrassed to ask but I don't get something really basic. When molecular oxygen and hydrogen react to produce water, we say the oxygen has been reduced and the hydrogen has been oxidised. ...
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1answer
129 views

In a battery, what happens to LiCoO2 when the lithium leaves? It becomes CoO2?

What chemical compound exists at the cathode of a lithium-ion battery when the lithium is not there? The cathode is usually described as $\ce{LiCoO2}$, so does it become $\ce{CoO2}$? $\ce{CoO2}$ ...
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2answers
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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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1answer
112 views

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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Why does the reaction of sodium nitrate, aluminium, and sodium hydroxide yield ammonia?

From Russian test problem 4301: $$\ce{3NaNO3 + 8Al + 5NaOH + 18H2O -> 8Na[Al(OH)4] + 3NH3(g)}$$ How does ammonia evolve here? Is it that we get hydrogen gas evolving in the reaction between Al ...
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0answers
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Why is addition of electronegative element to a substance considered as oxidation? [duplicate]

I'm confused to why oxidation with its other definitions also defined as addition of electronegative element to a substance, when at the same time in terms of electron transfer oxidation is also the ...
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1answer
49 views

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?
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1answer
50 views

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 ...
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2answers
385 views

How to balance this redox reaction taking place in a basic medium?

How to balance this reaction which is taking place in a basic medium? $$\ce{Al + MnO4- -> MnO2 + Al(OH)4-}$$ My Attempt Reduction half reaction: $$ \begin{align} \ce{4 H+ + MnO4- + 3 e- &-&...
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2answers
72 views

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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1answer
94 views

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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0answers
103 views

Name for reaction producing carbon from CO2

Some years ago I heard of a reaction where hydrogen could be used to reduce $\ce{CO2}$ to carbon and water, similar to the Sabatier reaction. I believe it also used iron as a catalyst at high ...
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1answer
3k views

Cr(II) and Mn(III) - their oxidizing and reducing properties?

My textbook states that $\ce{Cr^2+}$ is a reducing agent while $\ce{Mn^3+}$ is an oxidizing agent in spite of both having $\ce{d^4}$ configuration. The explanation states that when $\ce{Cr^2+}$ gets ...
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2answers
108 views

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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1answer
83 views

What (stored-as-solids) acids/liquids can clean corroded copper?

I'm looking for a liquid that can remove copper corrosion (oxides and basic carbonates - the black and green stuff) off copper piping. The corrosion will be located on the inside of the pipe, in hard-...
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1answer
66 views

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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1answer
129 views

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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1answer
83 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
71 views

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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4answers
8k views

Why doesn't iron(III) iodide exist?

$$\ce{Fe2O3 + 6HI -> 2FeI2 + I2 + 3H2O}$$ Why don't we get $\ce{FeI3}$? After all, iron's oxidation state is $+3$ in the reagent. Should one just memorize that up to bromine, it's $\ce{FeX3}$, ...
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2answers
10k views

What is this brown liquid that I got when I boiled glycerol and water solution?

I boiled a solution of glycerol and water at about 160 degree Celsius and got a brown liquid much less in volume (boiled off the entire water I think; also not so sure about the accurate temperature). ...
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3answers
6k views

Separating nickel coin into copper and nickel components

I'm trying to create a high school level lab in which we separate the metals in an alloy. The objective is to understand and apply standard reduction potentials, and also to do some extra redox ...
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2answers
117 views

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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1answer
268 views

How is indigo carmine used in Lowenthal-Permanganate titration as a redox indicator?

In a Lowenthal-Permanganate titration, cider tannins are quantified by titrating the cider with indigo carmine indicator and sulfuric acid against potassium permanganate. Tannins are antioxidants, so ...
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1answer
67 views

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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1answer
57 views

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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3answers
4k views

How does copper reduce dilute nitric acid to nitric oxide and concentrated nitric acid to nitrogen dioxide?

Here are the 2 equations: \begin{align} \ce{3Cu + 2NO3- + 8H+ &<=> 3Cu^2+ + 2NO + 4H2O} & E &= 0.62~\mathrm{V}\\ \ce{Cu + 2NO3- + 4H+ &<=> Cu^2+ + 2NO2 + 2H2O}& E &...
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1answer
53 views

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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1answer
85 views

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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1answer
43 views

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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1answer
4k views

How exactly does the oxidation of TEMPO by NaOCl/KBr work?

I would like to understand the exact process by which TEMPO is oxidized to the nitrosonium cation by NaOCl, as in the part of the mechanism shown in the diagram (1) surrounded by the red box: The ...
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1answer
112 views

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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1answer
5k views

What is the use of chloroform in the procedure of determining peroxide value?

In this procedure of determining peroxide value, the oil sample is dissolved in acetic acid chloroform solution. I understand that the acid is added so that the following reaction occurs $\ce{2ROOH +...
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1answer
47 views

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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0answers
46 views

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 ...
7
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2answers
563 views

Can hydrogen peroxide reduce ferric ion to ferrous ion?

I have studied that hydrogen peroxide always oxidizes ferrous ion to ferric ion (source of study : NCERT Chemistry Part II, Textbook for Class XI), but a question came in IIT JEE 2015 which states: ...
1
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1answer
68 views

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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0answers
31 views

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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2answers
22k views

Does Br2/H2O oxidize all aldehydes including carbohydrates?

In many books, it is mentioned that aldehydes are easily oxidized even by mild oxidizing agents. However, I have never seen bromine water explicitly mentioned. But in the carbohydrates chapter, it is ...

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