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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2answers
638 views

Confusion about the oxidation state of copper in copper cyanide re-dissolved with excess cyanide

$\ce{CuSO4}$ when reacts with $\ce{KCN}$ forms $\ce{CuCN}$ while it is insoluble in $\ce{H2O}$. It is soluble in excess of $\ce{KCN}$ due to the formation of the following complex: a) $\ce{K2[Cu(...
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2answers
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Is reduction of copper oxide a combustion reaction?

Is the following reaction a combustion reaction or just a single displacement? Could be both? $$\ce{H2 + CuO -> Cu + H2O}$$ A friend of mine claims it is a combustion reaction because it is ...
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2answers
90 views

Reaction between halogens and concentrated nitric acid

I have read that the reaction between $\ce{I2}$ and conc. $\ce{HNO3}$ gives $\ce{HIO3}$ and $\ce{NO2},$ but there is no mention of the other halogens' products. Do they all give halous acids and ...
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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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1answer
47 views

Is the effect of hydroperoxyl radicals significant in the oxidation of organic compounds in the Fenton reaction? Why or why not?

In the Fenton reaction, a ferrous catalyst and hydrogen peroxide are used to generate hydroxyl radicals which in turn oxidise organic compounds. The reaction is commonly seen in the treatment of ...
3
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1answer
427 views

What is the reaction between nitric acid and fluorine?

Nitric acid, $\ce{HNO3}$, is a strong oxidising agent as well as fluorine, $\ce{F2}$. What will be the reaction when pure $\ce{F2}$ gas is bubbled through 100% pure $\ce{HNO3}$. While searching, many ...
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0answers
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How do I solve redoxreactions when I dont know which elements are positive or negative [closed]

How do I solve a redox reaction when I dont know what is positive and what is negative? Na(s) + NiCl2(aq) Fe(s) + MgNO3(aq)
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1answer
67 views

What is the state of aggregation of iodine formed during electrolysis of molten nickel(II) iodide? [closed]

Assume the electrolysis of molten $\ce{NiI2(l)}$ (inert electrodes) in a cell. The cell with a heating element is in the room; the room is at $\pu{25 °C}$ and $\pu{101.3 kPa}.$ The half-reaction for ...
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Is it possible for a carboxyl group (R-COO-) to reduce a sodium ion? [closed]

Is it correct that a carboxyl group can act as a reducing agent, and, sodium as an oxidizing agent? R-COONa —> R-COO + Na+ + e-.
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What is the electron configuration of VO^2+ and VO3^1-? How do you determine the valence of vanadium in VO3^1- and VO^2+ [closed]

I am getting confused about how to go along with this so can someone please explain the process to figure this out as soon as possible :( Thank you! Also I was figured out that the oxidation number of ...
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How many electrons are exchanged in the following redox reaction? [closed]

$$\ce{\dfrac{2}{3}Al2O3 ->\dfrac{4}{3}Al +O2}$$ I tried splitting the reaction into oxidation and reduction half, but I got stuck. How do you balance the reduction half $\ce{Al2O3 ->O2}$?
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Why is chromate stable in basic medium and dichromate stable in acidic medium?

When I was studying the equilibrium existing between chromate and dichromate ions in the solution, I came to know that Chromate ion is more stable in basic medium while dichromate ion is stable in ...
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1answer
35 views

Which is a dye: Ferric Acetate or Ferrous Acetate?

I’ve been trying to make Iron Acetate to dye leather and I cannot, for the life of me, figure this out experimentally. I’ve been allowing steel wool to react with pure white vinegar in a sealed glass ...
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Chemical and Half Equations for the reaction between potassium permangante and glycerol [closed]

This quora thread has some half equations but they dont fit into this full equation given in the second link or the suggested chemical species in the third. Are the four different manganese species ...
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2answers
135 views

How to know dichromate is being reduced from Cr⁶⁺ to Cr³⁺?

When potassium dichromate is being used as an oxidising agent, it gets reduced from chromium(VI) to chromium(III). Is there any way to know that or calculate that other than being familiar with ...
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1answer
1k views

Balancing a redox equation with only one product

Is it possible to balance this equation using the half reaction method? $$\ce{Au + Cl2 + HCl⟶HAuCl4}$$ I know that the equation balanced would be: $$\ce{2Au + 3Cl2 + 2HCl⟶2HAuCl4}$$ However, how ...
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1answer
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Explaining the colour change in the potassium permanganate titration of iron(II) ions

In the redox titration: $$\ce{MnO4- + 8 H+ + 5 Fe^2+ -> Mn^2+ + 4 H2O + 5 Fe^3+}$$ the colour change which occurs is purple to colourless, because of the decreased concentration of permanganate ...
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1answer
64 views

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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0answers
26 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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2answers
501 views

Can aqua regia work 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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Possible methods for copper (II) reduction to copper (I)

How can I make $\ce{Cu2O}$ from copper? I am seeing if electrolysis is a good route (in the context of kitchen style chemistry) to cuprous oxide, instead of the traditional heating copper and ...
8
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2answers
12k views

Why does sodium react with water?

The reaction of sodium with water is quite infamous. $\ce{2Na + 2H_2O \rightarrow 2NaOH + H_2}$ But exactly why does $\ce{Na}$ displace $\ce H$ in $\ce{H_2O}$?
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How is it determined how many electrons are transferred in redox reactions?

For example, iron and tin(II) sulfate will react to produce iron(II) sulfate and tin: $\ce{Fe + SnSO4 -> FeSO4 + Sn}$ With the following half equations: $\ce{Fe + SO4^{2-} -> FeSO4 + 2e-}$ ...
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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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1answer
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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
24 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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How does standard reduction potential state which of the two ions of an element is more stable?

In my book it is written that $\ce{Pb^2+}$ is more stable than $\ce{Pb^4+}$ and the reason was stated that as the reduction potential of $\ce{Pb^4+}$ becoming $\ce{Pb^2+}$ is $1.8$, whereas the ...
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2answers
77 views

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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4answers
364 views

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 were oxidized to $\ce{Cl2}$. But we don't see any $\ce{O^2-}$ at all. My pre-...
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3answers
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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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2answers
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Reaction of white phosphorus with aqueous sodium hydroxide

What are the products obtained in the reaction of white phosphorus with aqueous sodium hydroxide? I know one will be phosphine ($\ce{PH3}$). How can we find the oxidation state of phosphorus in the ...
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2answers
97 views

Experimental measurment of thiosulphuric acid decomposition kinetics

Problem I am trying to do a kinetics analysis on the following reaction: $$\ce{Na2S2O3 {(aq)} + 2 HCl {(aq)} -> S {(s)} + 2 NaCl {(aq)} + SO2 {(g)} + H2O {(l)}}$$ Suggested Method However, most ...
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1answer
34 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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1answer
42 views

How should I think so as to discover the Half reaction method?

The ion electron method aka half reaction method. This method works amazingly in balancing out chemical equations. I have tried solving chemical equations algebraically, and it is the same, except ...
3
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1answer
74 views

Reactions involved in Titanium Anodisation

I am writing up a lab report investigating titanium anodisation and producing oxide layers. After some searching, all I can find is the reaction $\ce{Ti + O2 \to TiO2}$, which I am having no trouble ...
3
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1answer
270 views

Safely lowering bleach pH without chlorine gas?

According to Eurekalert, by lowering the pH of household bleach (e.g., by adding vinegar or citric acid), we can increase $\text{[HOCl]}$ and consequently greatly improve the disinfecting capabilities ...
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0answers
42 views

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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1answer
90 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 ...
3
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1answer
980 views

How exactly does a battery work (specifically Pb/H2SO4/H2SO4/PbO2 lead acid battery)?

Specifically talking about the lead-acid battery, I understand (or think I understand) this much: The anode, in the presence of the electrolyte, $\ce{H2SO4}$ will be oxidised: $$\ce{Pb (s) + SO4^2- (...
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1answer
130 views

Finding moles of different compounds using balancing

$$\ce{K2Cr2O7 + $x$\,H2SO4 + $y$\,SO2 -> Cr2(SO4)3 + K2SO4 + $z$\,H2O}$$ For $\ce{Cr}$ change in oxidation number is: $+12$ becomes $+6$ For $\ce{S}$ change in oxidation number is: $+4y$ becomes ...
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0answers
56 views

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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2answers
550 views

Why is fluorine a oxidising agent?

An oxidizing agent pulls the electron cloud of the substance being oxidized towards itself, for example: $$\ce{F2 + 2 X- -> 2F- + X2}\qquad (\ce{X} = \ce{Cl}, \ce{Br}, \ce{I})$$ We also know ...
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0answers
42 views

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 ...
3
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0answers
16 views

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 ...
8
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1answer
83 views

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
52 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{...
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1answer
44k views

Difference in the functioning of alkaline and acidified KMnO4

What is the difference in the functioning of alkaline and acidified $\ce{KMnO4}$ as a reagent in organic chemistry? E.g., in the oxidation of a primary alcohol to carboxylic acid, we use acidified $\...
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0answers
27 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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0answers
13 views

Calculation of the Halfcellpotential (equilibrium constant is missing the solvent water) [duplicate]

Suppose the following Rredox reaction of Br in Water: $BrO_3^-+6H^++6e^-\iff Br^-+3H_2O$ Next the text book claims the following about the corresponding equilibrium constant: $K=\frac{[Br]}{[BrO_3^...

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