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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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Oxidation of Fe to Fe3+ (corrosion)

Why does $\ce{Fe}$ get oxidized directly to $\ce{Fe^3+}$ if $\ce{O2}$ is present, but only to $\ce{Fe^2+}$ if oxygen is not present? I've tried comparing the half reactions: \begin{align} \ce{Fe &...
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0answers
250 views

What are the factors that affect the redox reactions?

In my work, I used $\ce{Co(OH)2}$ and $\ce{Ni(OH)2}$ as an active materials to fabricate as symmetric supercapacitors in which I used 1-butyl-1-methylpyrrolidinium dicyanamide as an electrolyte. From ...
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3answers
5k views

Why the colour of KMnO4 at the end point of titration may disappear after some time?

In the redox titration of $\ce{FeSO4}$ with $\ce{KMnO4}$, the colour change of the solution at the end point is colourless to light pink. Most laboratory manuals and books advice us to check whether ...
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1answer
46 views

Quantity of water in a redox problem

$\pu{76 g}$ of $\ce{FeSO4}$ are oxidized by $\pu{0.04 M}$ solution of $\ce{KMnO4}$ in presence of $80\%$ $\ce{H2SO4}$. What quantity of water must be added to the final solution of $\ce{Fe2(SO4)3}$ ...
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2answers
264 views

Will sodium sulfite effect the oxidization of toluene to benzoic acid with potassium permanganate? [closed]

I am trying to oxidize toluene to a mixed salt $\ce{K/Na}$ benzoate/ benzoic acid using the potassium permanganate method, but I am using OTC sourced $\ce{KMnO4}$ which has a significant amount of ...
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1answer
268 views

Will nitrate be able to oxidise mercury?

We have the following data: \begin{align} \ce{NO3- + 3 e- &-> NO} &\quad E^\circ_1 &= \pu{0.96 V}\\ \ce{Hg^2+ + 2 e- &-> Hg} &\quad E^\circ_2 &= \pu{0.86 V} \end{align} ...
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0answers
28 views

When performing an experiment looking at the effect of pH, will titration as a method of analysis change the pH during analysis?

I am designing an experiment looking at the effect kf pH on the oxidation state of Fe ions. Basically, I will be dissolving ferrous sulphate in different concentrations of sulfuric acid (0.1M-5M), ...
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0answers
540 views

How do I balance the reaction equation of zinc and nitric acid?

How would you balance the following reaction using the oxidation number method? $$\ce{Zn + HNO3 -> Zn(NO3)2 + NH4NO3 + H2O}$$ My approach: Half reactions: \begin{align} \ce{Zn &-> Zn(NO3)2}...
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1answer
3k views

What is the product of the titration of potassium permanganate and iron(II) sulfate?

I recently did an experiment at school, where I had to titrate KMnO4 with FeSO4. The solution was colourless, then turned yellowish until the end point was reached and it turned pink in one drop. ...
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1answer
1k views

Calculating n factor of SO2

I'm having a hard time trying to figure out n factor of $\ce{SO2}$ in the reaction $$\ce{FeS2 + O2 → Fe2O3 + SO2}\qquad \text{(unbalanced)}$$ To balance it, I saw that in 1 mole of $\ce{FeS2}$, it ...
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0answers
62 views

Kinetics of nitric oxide production

Several articles affirm that NO can enhance the glutamate release from the presynaptic site; moreover, glutamate has been recognized as a major brain neurotransmitter and is considered to mediate ...
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1answer
244 views

How do I solve oxidation numbers for unknown elements? [duplicate]

I am doing very well with oxidation numbers but I have a few problems. I know all the rules but when I get an element where I can't use any of the constant oxidation numbers what do I do? For example: ...
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2answers
99 views

Identification of a metal from group 2 [closed]

A chemist adds $\pu{0.115 g}$ of a group 2 element to water and the resulting solution is made up to $\pu{400 cm3}$ by adding distilled water. The equation for the reaction is shown below. $\ce{M}$ ...
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0answers
114 views

Ionizing radiation and oxidation without oxidizing agents

My knowledge on this subject is a bit rusty, so excuse me if I'm asking the wrong question here. I was taking a look at my high school chemistry books from many years ago, and I noticed that reduction ...
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2answers
420 views

water in redox reactions [closed]

why water can't react as anode , with metals , in a redox reaction? while studying electrochemistry, i passed through a table with certain metals , all having voltage (potential energy) less than ...
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1answer
82 views

Balancing of redox reaction [closed]

I tried to balance the following redox reaction $$\ce{S^0 + OH- -> S^2- + S2O3^2-}$$ by ion electron method, but I am unable to identify the oxidation and reduction half reactions. Please ...
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1answer
808 views

Oxidation of water by permanganate: Does this reaction happen?

Since MnO4- is a strong oxidiser, if one increased its concentration relative to water, could it oxidise the water (Le Chatelier's Principle seems to suggest so)? I have attempted to write the ...
3
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0answers
81 views

Is this model to explain children about oxidation and fire correct? [closed]

I am teaching two young boys (elementary school) some basics about chemistry, but I have to learn as I go myself. Is this a viable model to explain oxidation and fire? When we light up the fireplace,...
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1answer
63 views

Is this definition of the verb oxidize correct? [closed]

UPDATED VERSION: There are a dozen definitions of the verb oxidize in various dictionaries. My question is whether the definition in the end of this post holds true. I have added the words in bold. ...
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0answers
44 views

polyiodide complex and reduction of lead

I have lead sulfide film submerged in solution containing dissolved KI and iodine. My film is converted to lead iodide and some of the lead is reduced to metallic lead.I was not able to find in the ...
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1answer
655 views

When an iodide/iodate solution is acidified with H2SO4 instead of thiosulfate, why should it be titrated immediately?

My class is currently performing a reaction to determine the oxidizing power (i.e. the amount of hypochlorite) of household bleach. The general process is as follows: Standardize thiosulfate to be ...
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2answers
541 views

Is a combustion necessarily a redox-reaction or can there be exceptions?

I have a feeling that I have heard of an exception - either based on the material or the oxidizer.
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0answers
148 views

What happens when dissolving Al in dilute HCl

I'm about to dissolve $\ce{Al}$ in $\ce{HCl}$ dilute to obtain an electrolyte. What reactions are taking place here? I'm aware that $\ce{Al}$ and $\ce{HCl}$ produce $\ce{AlCl3}$ and $\ce{H2}$. But ...
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2answers
157 views

Why do electrodes need to share an electrolyte in a lemon battery? [closed]

From what I understand of a lemon battery, there are two electrodes one zinc, and one copper. The electrodes are then both placed separated in the same electrolyte, in this case a lemon. The Zinc ...
6
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1answer
50 views

How can compounds be called reduced if nothing is known about the reaction they formed in?

I'm reading a research article about a model trying to explain the elemental compositions of meteorites.[1] What confuses me, are statements of the following type (here in chapter 2.1, second ...
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0answers
80 views

Can a nitro compound be reduced to an amine by electrolysis?

Several methods are known for the reduction of a nitro compound to an amine, including catalyctic hydrogenation. I am wondering if this can be done by electrolysis. If we take the simplest ...
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0answers
277 views

The function of sulfuric acid in a reaction involving halide ions

The purpose of the following reactions is to make halogen gas: \begin{align} \ce{2 NaCl (s) + MnO2 (s) + \boxed{\ce{2 H2SO4 (l)}} &-> Na2SO4 (s) + MnSO4 (s) + 2 H2O + Cl2 (g)} \\ \ce{10 KI (...
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0answers
542 views

Oxidation of Magnesium with Nitric Acid

Write an unbalanced equation for the following: Magnesium metal is added to dilute nitric acid. My attempt: Nitric acid commonly oxidizes metals and gets itself reduced in the process - to $\ce{NO}$ ...
2
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0answers
62 views

Problem regarding failure of equivalence concept

Chile salt peter, a source of $\ce{NaNO3}$ also contains $\ce{NaIO3}$. The $\ce{NaIO3}$ can be used as a source of iodine, produced in the following reactions. \begin{align} \ce{IO3- + 3 HSO3- &...
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1answer
353 views

How many atoms can be reduced in a single redox reaction?

I am doing high school chemistry and I am busy working with redox reactions. The explanation in my text book, of how a redox reaction works, left me a bit confused as to how many atoms can be reduced/...
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1answer
283 views

Decomposition of AsH3

In German problems olympiad 2014, the solution says that decomposition of arsine is not a redox reaction. Why would that be? Shouldn't H turn from -1 to 0 and As from 3+ to 0? $$\ce{2AsH3 -> 2As + ...
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1answer
69 views

Replacement for Centrifuge in Calcium Content Determination

Basically, I'm performing a lab investigation to determine calcium content in different milk sorts. Since my school didn't have any EDTA, I'm using Sodium Oxalate to form a precipitate with Calcium ...
6
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1answer
538 views

Why don't ligands affect the oxidation state of the central metal ion?

If $\ce{Fe^3+}$ were complexed with 6 $\ce{H2O}$ ligands, the resulting complex ion would be $\ce{[Fe(H2O)6]^3+}$, and the central metal ion would still have the same oxidation state of +3 as it did ...
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1answer
547 views

Net ionic equation for a synthesis reaction?

In the following reaction $$\ce{S (s) + O2 (g) -> SO2 (g)}$$ there are no spectator ions because both $\ce{S}$ and $\ce{O2}$ take part in the reaction. Does that mean the net ionic equation is ...
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2answers
958 views

Rearrangements of α-aminoketones in Clemmensen reduction

What is the possible mechanism for this reaction? Activated zinc in presence of concentrated hydrochloric acid is used for Clemmensen reduction, that is conversion of ketone group to methylene group. ...
4
votes
1answer
61 views

How do the toxicities of arsenate and arsenite compare?

So I was browsing the detoxification metabolistic mechanisms for E. coli, and came across an arsenic detoxification mechanism that converted arsenate to arsenite using a glutaredoxin. So my question ...
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1answer
576 views

Sodium metal in acetone

When I place a chunk of 99,99% pure sodium metal in a beaker of (100% chemically pure) acetone, the sodium metal starts reacting and dissolving into the acetone and it forms a yellow/brown liquid. ...
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2answers
1k views

Can a solution of FeCl2 go bad over time?

My lab has been using solution of FeCl2 for an assay that was mixed about three years ago. Recently the assay has failed twice. I was wondering if it is possible that the iron ions in the solutions ...
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2answers
2k views

Can cat urine corrode stainless steel?

My cat has a habit of urinating in the bathroom sink. It is unsanitary, but can it corrode the stainless steel plumbing hardware? My friend believes it will, but I disagree. I could believe that if ...
4
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1answer
130 views

Is a spectrophotometric method of measuring the rate of a complex reaction valid?

A few months back I designed and carried out an experiment to measure the rate of the reaction between ferric chloride and copper.The dependent variable was the rate of the reaction; the independent ...
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1answer
112 views

What's the mechanism of water catalyzing a reaction of hydrogen sulfide gas and sulfur(IV) oxide to yield sulfur?

The reaction $$\ce{2 H2S(g) + SO2(g) -> 2 H2O(l) + 3 S(s)}$$ goes in presence of a catalyst, usually $\ce{Al2O3}$ or $\ce{TiO2}$, but also just in presence of moist or water (YouTube video) I ...
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0answers
29 views

For a system containing three reductants, can a combined reduction potential be determined?

I've modelled a system and found that there are three major complexes present at equilibrium, all of which I hope will act as reductants when I add an additional, oxidised species. Each of the three ...
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0answers
58 views

Understanding how to choose the right reaction for electrochemistry [closed]

I am quite new here and studying a bit of electrochemistry. In the course of my studies I encountered a problem I couldn't figure out: A sample of iron ore weighing $\pu{0.2792 g}$ was dissolved in ...
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2answers
3k views

Why does ozone disproportionate on reaction with potassium iodide?

In this redox reaction, iodide ion is oxidized to iodine and ozone reduces to hydroxide ion. $$\ce{2KI + O3 + H2O -> I2 + O2 + 2KOH}$$ This seems like a redox reaction since iodide ion is getting ...
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2answers
542 views

Single electrode potential measurement

My textbook says that in a galvanic cell, it's not possible to measure single electrode potential independently. Instead, a Standard Hydrogen Electrode is used as the system is under equilibrium. Can ...
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1answer
283 views

Do I use the Nernst equation when the concentrations of electrolyte in both half cells are equal?

I'm doing a chemistry report, and for my experiment I investigated the amount of voltage produced by different half cells in a voltaic cell. However, I tested them under nonstandard conditions as ...
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0answers
305 views

What defines the oxidizing/reducing power of a coordination compound?

For example, I came across a problem in which I was asked to determine whether the complex $\ce{[Cr(H2O)6]Cl2}$ is an oxidizing or reducing agent. How should I proceed? My teacher told me its the ...
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0answers
156 views

Acidified sodium sulfite in the reduction of iron(III) to iron(II)

Why does sodium sulfite have to be acidified in the reduction of $\ce{Fe^{3+}}$ to $\ce{Fe^{2+}}$? Does the acid act simply as a catalyst or is it necessary for the reduction process?
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1answer
101 views

Calculating molar mass of an oxidant by iodometry

I am stuck on a question from the Australian Chemistry Olympiad involving molar mass, shown here: BTW, this whole paper is available online for free, and is distributed by its owners for free. Just ...
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1answer
287 views

Reaction mechanism of redox reaction

So on the data, it said that we can reduce potassium permanganate by utilizing oxalic acid, thus producing carbon dioxide. But can anyone propose a reaction mechanism of how the whole reaction happens,...