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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201 views

Effect of charge density on electrolysis of dilute sulphuric acid

I am told that if electrolysis of dilute sulfuric acid is performed under high charge density, then the following reaction takes place at anode instead of evolving oxygen: $$\ce{2 HSO4- -> H2S2O8 +...
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571 views

Can aqua regia/royal water be produced with sources of chloride and nitrate other than hydrochloric acid and nitric acid?

According to Professor Poliakov and a question on Chemistry Stackexchange here, gold dissolves in aqua regia because the nitrate ion oxidizes the gold into $\ce{Au^3+}$, and the chloride bonds to the ...
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Are there acid/base processes in aqueous solution that are so slow that they are kinetically controlled?

This question came up in figuring out what the fundamental differences are between redox chemistry and acid/base chemistry (if any). In redox chemistry, strong oxidants and strong reductants can co-...
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In acid/base chemistry, are there amphoteric substances that undergo something that resembles disproportionation in redox chemistry

Some substances disproportionate. This means a species with an intermediate oxidation state yields two species with higher and lower oxidation state. For example: $$\ce{Hg2Cl2 -> Hg + HgCl2}$$ My ...
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1answer
30 views

Limiting the minimum percentage of oxygen in atmosphere maintained by an oxygen absorber / scavenger?

I'm aware that oxygen in the atmosphere of a sealed package can be readily removed by using oxygen absorber/scavenger such as granulated iron and sodium chloride but my understanding is that these ...
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Predicting in which medium will the oxidation occur [closed]

The image above contains the redox half-reaction for Mn2+ oxidation and their standard electrode potentials. The first two are in base medium and the second two are in acid medium. How can I predict ...
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4answers
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In NaCl electrolysis, why does chlorine ion get oxidized but not oxygen ion? [closed]

In $\ce{NaCl}$ electrolysis, on the positive electrode (aka. on the electrode where oxidation happens), $\ce{Cl-}$ ions are oxidized to $\ce{Cl2}$. But why don't we see any $\ce{O^2-}$ (naturally ...
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Copper acetate solution turning clear

I made a solution of copper acetate using 5% Acetic acid 3%hydrogen peroxide and copper wire and copper pipe and it had produced a blue solution of copper acetate. I left it over night to continue ...
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1answer
48 views

What is the easiest way to concentrate a solution without causing it to hydrolyze?

I’ve been working with iron acetate solutions in dilute acetic acid (vinegar) and I’ve been running into a problem. Every time I try to boil off the solvent the solution hydrolyzes to form iron oxides....
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why is HClO a better oxidizing agent than HClO2, HClO3, HClO4? [duplicate]

Why do the oxoacids of chlorine have the following order of oxidizing power: HClO > HClO2 > HClO3 > HClO4 ? When I search it online, many posts say "because the oxidation state of Cl in HClO is the ...
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Equilibrium cell potential question

In an attempt to wrap my head around the basics of electrochemistry I'm working my way through Wesley R. Browne's 'Electrochemistry' primer. With regards to the equilibrium potential of an ...
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Possible side reactions in electrolysis of concentrated NaCl

This is a very basic question about which side reactions can take place if the electrodes are not shielded from each other during electrolysis of concentrated $\ce{NaCl}$. So, this is the desired net ...
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Is my understanding of cyclic voltammetry correct? [closed]

So recently I've been roped into doing some CV and I'm trying to wrap my head around the fundamentals of the science behind it (and electrochemistry more generally! Bare in mind I'm very much not an ...
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Can pheophytin be converted back to chlorophyll?

Some fossil leaves are "greenish" when first exposed but rapidly darken to an "olive brown" color when they come into contact with air. If the fossil leaf contains pheophytin, can the addition of ...
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1answer
161 views

Is this galvanic cell representation right?

Question 13. In the galvanic cell: $$\ce{Pt(s) | I2(g) | I-(aq) || Fe^3+(aq) | Fe^2+(aq) | Pt(s)}$$ Representation of anode is incorrect and cell will not work. $[\ce{Fe^3+}] = [\ce{Fe^2+}] = [\ce{I-...
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Why does the corrosion of a steel nail develop iron ions in the ends of the nail and hydroxide in the middle of the nail?

We did an experiment in school where we put a steel nail in a solution consisting of: 1 g agar; 100 ml water; 100 ml indicator solution (which gets blue whenever $\ce{Fe^2+}$ is created and red when $...
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1answer
59 views

Industrial production of alkali metals

My professor says that $\ce{Li}$ and $\ce{Na}$ are produced by electrolysis, while $\ce{K, Rb}$, and $\ce{Cs}$ are made via the reaction $\ce{Na + MCl -> NaCl + M}$, where $\ce{M = K, Cs, Rb}$. I ...
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1answer
412 views

Reaction of 1,2-diketones with periodic acid [closed]

$\ce{HIO4}$ can oxidise alcohols. But does $\ce{HIO4}$ undergo any reaction/act as oxidant with 1,2-diketones?
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pH implications of redox balancing half reaction method

I have seen similar questions, but I’m asking a new question as far as I know. Why is water instead of hydroxide ions used to balance oxygen atoms in redox half equations? asks about using hydroxide ...
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1answer
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Is there any evidence, *any evidence at all*, that nascent hydrogen actually exists?

As far as I know, nascent hydrogen is nothing more than an especially magical unicorn entity that either makes reactions happen or at least greatly facilitates reactions happening. Many years ago, it ...
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4answers
843 views

If you placed silver metal into silver nitrate, would a reaction occur? [closed]

thinking about oxidation and reduction, what happens to the silver metal and the silver ions?
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2answers
72 views

Writing half equation confusion [closed]

The following is the answer for a question that I am doing: Reduction: $\ce{X^2+(aq) + 2 e- -> X(s)}$ Can I write $\ce{X + 2 e- -> X^2-}?$ Why can't I start with $\ce{X}$ instead of $\ce{X^2+...
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1answer
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Which is a better electrolyte for electroplating copper? [closed]

I need to know which is a better electrolyte to use when electroplating copper: copper sulfate or copper nitrate?
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Thermal reduction of other metal oxides beside Fe2O3

In the firing of ceramic glazes you can make an effect called oil spot. This is done by making two layers of glaze. A bottom layer rich in iron oxide (+15%) and a top white layer that's fairly ...
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How do the two half cells of Daniel cell know when they are connected?

I'm currently studying electrochemistry in school, and there is something I don't can't quite understand about Daniel cell. When you put $\ce{Zn}$ solid into $\ce{ZnSO4}$ solution, does the electrode ...
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1answer
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Equation for Galvanization and Electrolysis of Saltwater with Copper and Zinc

I am looking for the chemical equations for both the galvanization and electrolysis of saltwater utilizing copper and zinc. The closest I have gotten was from this site: Explanation for the reactions ...
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3answers
116 views

Balancing redox equations with oxygens in multiple oxidation states

How do you balance this using the ion-electron method; $\ce{CrO5 + H2SO4 -> Cr2(SO4)3 + H2O + O2}$ The oxygen has multiple oxidation states in $\ce{CrO5}$, and none of the sites I looked this up ...
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1answer
135 views

Electrode potentials vs interfacial potential differences

Between an electrode and an electrolyte there exists an interfacial potential difference. Many authors give the electrode potential to be the electric potential of the electrode relative to the ...
2
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1answer
308 views

Does the order of a written redox couple matter?

My understanding is that a redox couple is an unordered pair of two conjugate species. So we could speak of the redox couple consisting of $Ag$ and $Ag^+$; depending on whether a given redox couple is ...
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1answer
77 views

Most understandable notation for reduction and oxidation potentials

Nowadays a lot of electrochemistry is done using just electrode potentials (i.e. reduction potentials), so if in doubt the notation $E^o$ tends to imply a reduction potential. However, some chemists ...
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1answer
307 views

Why do we write electrode potentials next to chemical reactions? [closed]

We might have a half cell consisting of the redox couple $\ce{Ag+}/\ce{Ag}$, which for example's sake might be fixed to be at the cathode (i.e. undergoing reduction). The reaction at the cathode is ...
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62 views

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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2answers
613 views

Why ZnS can be seen as the solution is made alkaline? Explain with reactions [closed]

There is an extract in my book which i am not able to get. It says: Place strip of metallic zinc in aqueous solution of copper nitrate for about one hour. You may notice that the strip becomes coated ...
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2answers
352 views

Equations for the oxidation reactions of tea teaflavins and EGCG with potassium permanganate

For my chemistry investigation, I used Stamm's potassium permanganate method to investigate tea tannins with potassium permanganate to find the tannin content of teas. The method assumes complete ...
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2answers
103 views

Indicators of Cu(I) or Cu(II)

We performed an experiment in class where we placed a piece of copper wire in a solution of silver nitrate, we were tasked with predicted the mass of copper that should react and the mass of silver ...
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1answer
899 views

Nernst Equation for Lithium ion battery

For electrochemical cells we know $$ \Delta G = \Delta G^{\ominus} + RT\ln Q=- RT\ln Keq + RT\ln Q=-nFE $$ So for lithium ion batteries the reactions are Cathode $$ \ce{CoO2 + Li+ + e- <=> ...
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2answers
385 views

What is the oxidation state of Boron in Ammonia Borane? [closed]

So I was searching about the difference between redox reactions and Lewis Acid-Base reactions and came across classical example of latter, $$\ce{NH3 + BH3 \rightarrow NH3BH3}$$ Now in this example ...
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1answer
802 views

How to predict disproportionation products from Frost diagram?

I read that concave points in a Frost diagram disproportionate. But what are the products of the disproportionation? For example, in the Frost diagram for manganese at pH = 0, the species $\ce{HMnO4-}...
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1answer
446 views

Why is the voltage produced by a voltaic cell affected by temperature as described by the Nernst Equation?

I understand why changing the concentrations of the electrolytes in a voltaic cell affects the voltage. Given a zinc-copper cell for example, if I were to increase the concentration of the zinc ...
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1answer
73 views

Predicting directions of redox reactions [closed]

Hello! In this textbook example question, how come the chlorine reaction, which has the greatest reducing power will not react? If it has the greatest E of 1.36 V that means it has most reducing ...
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1answer
46 views

Electrochemistry - Understanding Diffusion Potential

I have a big problem trying to wrap my head around this for several hours and I cannot seem to make sense of it. I have to link this scheme with the 3 colored potential profiles on the bottom of the ...
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2answers
603 views

Is anode actually ever negative?

Disclaimer: This question comes from a physics student. I was studying electrostatics and I was wondering how to charge a conductor at home without any fancy furs etc. So an idea came to me: take a ...
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103 views

Why does changing the salt of the salt bridge effect the voltage produced in a galvanic cell?

My experiments results showed that the voltage decreases down $\pu{Group 1}$: $\ce{Cl-}$ salts in the salt bridge. All other variables were kept constant. $\ce{Zn}$ and $\ce{Cu}$ rods were used. ...
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0answers
254 views

Colour of VO3^-?

To aquire the yellow colour of vanadium ion, it must be present in a 5+ oxdiation state. This can be acheived (according to my textbook) by adding dilute sulfuric acid to $\ce{NH4VO3}$, then followed ...
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2answers
112 views

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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1answer
107 views

What is the meaning of parentheses in “NAD(P)H”?

If someone writes "NAD(P)H is oxidized by ...", does that mean they are referring to both NADH and NADPH? If so doesn't that lead to confusion when thinking quantitatively since the reactions may ...
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89 views

Galvanic Cell Temperature Dependence

I'm currently studying the temperature dependence of the following cell: $\ce{Cu_{(s)} + 2Ag^{+}_{(aq)} <=> 2Ag_{(s)} + Cu^{2+}_{(aq)}}$ ($E^⦵ = \pu{+0.46 V}$) Experimentally, I recorded the ...
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1answer
289 views

Understanding sodium hydroxide drain cleaner's exothermic dissolution of aluminum; does the aluminum need to be oxidized before it dissolves?

I'm not a chemist but I remember that the standard HF/nitric silicon etch used in micro-fabrication supposedly worked in two steps; the HF would dissolve the thin SiO2 oxide layer on the silicon ...
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1answer
2k views

How can AuCl3 exist?

The reduction potential for $\ce{Au^3+ + 3e- -> Au}$ is $1.503 \text{ V}$. The reduction potential of $\ce{Cl2 + 2e- -> 2Cl-}$ is $1.36 \text{ V}$. So, the $E^o$ for $\ce{2Au^3+ + 6Cl- -> 2Au ...
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0answers
29 views

Can Methylene Blue Detect Spoilage in Food?

Initially, there is already a product which is a sensor based on Methylene Blue, which can detect changes in oxygen levels in a packaging. However, as our thesis project, we decided to take on this ...

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