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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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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,...
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1answer
88 views

Ketone/aldehyde synthesis from N-acylazetidines or aziridines

A common principle in organic chemistry is to make sure the product is less reactive than the starting material, to prevent overreaction. So, for example, the treatment of an ester with a Grignard ...
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1answer
65 views

Why is oxygen oxidized with lead instead of being reduced?

Oxygen is more electro negative yet in the redox reaction $$\ce{2PbO(s) -> 2Pb(s) + O2(g)}$$ my text book says lead is reduced and oxygen is oxidized. How can this be? It doesn't make sense to ...
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102 views

Is dimethyl disulfide a reducing agent or oxidizing agent?

I am trying to explain to my colleague that DMDS is a reducing agent since each sulfur have 2 lone pair electron and has oxidation state of neg two. The electronegativity of sulfur is a lot lower than ...
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692 views

What is the role of the sulfuric acid in a titration between potassium permaganate and iron ammonium sulphate solution?

So basically my titration was of finding the concentration of potassium permaganate against an iron ammonium solution. In the iron ammonium sulphate solution it consisted of water, iron ammonium ...
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0answers
57 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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2answers
134 views

Partial reactions in redox formation of rust

In the iron oxidation that results in rust, the first step is to steal 2 electrons from $\ce{Fe}$. The main thief is said to be the oxygen dissolved in water, witch uses the stolen electrons to form $\...
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0answers
52 views

Reducing strength of (i-Bu)2AlH vs Lithium aluminum tri(t-butoxy)hydride

Hi Im trying to figure out which of the following is the stronger reducing agent. (i-Bu)2AlH vs Lithium aluminum tri(t-butoxy)hydride From my understanding, the Lithium aluminum tri(t-butoxy)hydride ...
5
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1answer
708 views

Why sodium is the worst reducing agent in group 1?

Analysing the oxidation enthalpies for $\ce{Li}$, $\ce{Na}$ and $\ce{K}$, we have their respective values: $\ce{Li} = \pu{162 kJ/mol}$ $\ce{Na} = \pu{202 kJ/mol}$ $\ce{K} = \pu{188kJ/mol}$ Sodium ...
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55 views

Corrosion issue at large DC current

I'm no expert in chemistry, but I know that corrosion can cause great problems in systems. I'm working on a prototype, and trying to figure out if corrosion will cause issues. The setup Imagine the ...
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2answers
805 views

Oxidation of an aldehyde - how is this a loss of electrons?

I've been reviewing redox reactions and have been using the OIL RIG acronym to classify oxidations vs. reductions. Generally this makes sense, and many resources I've looked at repeat the "Oxidation ...
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25 views

Regarding rate dependence on redox potential

I am stuck with an equation wherein chloroauric acid reacts with oxalic acid to form Au(s). Even though one of both are enough for the reaction: How does the rate change with increased oxalic acid? ...
9
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1answer
522 views

Reaction mechanism for the synthesis of 9,10-phenanthrenequinone

In my lab course I had to synthesize 9,10-phenanthrenequinone (phenanthrene-9,10-dione) from phenanthrene and chromium(VI) oxide. The synthesis was made as explained in Organic Syntheses, Coll. Vol. 4,...
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1answer
66 views

Measuring Cu2O Thickness in Oxidized Copper Sheet

I have Cu2O fabricated using thermal oxidation of Cu sheets in air at high temperatures. The thickness of Cu2O is expected to be at least 100 microns. There is still plenty of unoxidized Cu metal ...
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0answers
93 views

Why do lower oxygen concentrations lead to an increase the rate of corrosion?

Is this only the case in pitting corrosion? Is it because metal which has access to the oxygen becomes cathodic leading to the inaccessible parts of the metal becoming anodic?
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1answer
73 views

Oxidation - Reduction Ionic Half Reaction

Trying to figure out how to balance the following molecular equation: $$\ce{KMnO4 + Na2C2O4 + H2SO4 -> MnSO4 + CO2 + Na2SO4 + H2O}$$ I have compiled all of their oxidation states $$\ce{KMnO4 + ...
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1answer
160 views

Folin–Ciocalteu formula

I am searching a long time now. I have a question about the Folin–Ciocalteu formula for quantification of polyphenol. How is the $62.5$ in the equation explained? Where does it come from? This is the ...
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2answers
1k views

Oxidizing agent, reducing agent, acid or base

In concrete reactions, how can you define whether Ammonia reacts as an oxidizing agent, reducing agent, an acid or a base? I'm confused because in the examples given it's not an acid/ base when an $\...
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1answer
203 views

Why does the iron rust with less salt

For my school project I was going to measure the rate that salt has on the rusting of iron. To do this I set up an experiment where I had 15 beakers containing 200 milliliters of distilled water. I ...
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3answers
1k views

Identifying spontaneous redox reactions

Which one of the processes is NOT spontaneous? \begin{align} \ce{Ni + Sn^2+ &-> Ni^2+ + Sn} \label{1} \tag{1} \\ \ce{Cu + Fe^2+ &-> Cu^2+ + Fe} \label{2} \tag{2} \\ \ce{Ni + 2Ag+ &...
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2answers
2k views

What happens if hydrogen peroxide is added to silver oxides? [closed]

I have some powders that contain $\ce{Ag2O}$ and $\ce{AgO}$. What happens if I add $\ce{H2O2}$ and some water to these silver oxides?
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1answer
83 views

What is the effect of Helium-based surroundings (99% Helium) on electrochemical gas sensors?

I am currently working on a project measuring gas composition of car exhaust. In order to dilute the gas concentration down to something electrochemical sensors can read, I diluted the sample with ...
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1answer
1k views

Reduction of a ketone to an alkane

What is the mechanism for the reduction of ketone to alkanes using $\ce{H2}$, $\ce{Pd/C}$ in ethanol? Searching on Google mostly yields the reduction of ketones to secondary alcohols using LAH.
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2answers
147 views

Oxidation and reduction in organic chemistry

Why is it that in order to make an carboxylic acid from an alcohol you oxidise it twice... ie alcohol + 2[O] ---> carboxylic acid ...but to get back to the alcohol you reduce it four times? ...
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2answers
3k views

Why would a solution of FeCl2 appear brown/yellow sort of like FeCl3?

If we prepare a solution of $\ce{FeCl2}$ by dissolving solid $\ce{FeCl2}$ powder in water, supposing the bottle of $\ce{FeCl2}$ was left open for sufficient time, is it possible for $\ce{FeCl2}$ to ...
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1answer
1k views

How does a salt bridge in a galvanic cell neutralize each half cell? [closed]

I am not exactly sure what purpose the salt bridge has. In the above image, I understand that electrons flow from $\ce{Zn}$ through the wire to $\ce{Cu}$ due to the redox reaction. However, I do not ...
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0answers
50 views

What would an ecosystem based on reducing atmospheres be like?

I was wondering, what would it be like if instead of an oxidizing atmosphere like earth has, if an ecosystem had a reducing atmosphere instead? My professor told us that a system like that could be ...
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1answer
2k views

Why does potassium dichromate always reacts in an acidic medium?

On the other hand, potassium manganate reacts in both acidic and alkaline media.
3
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1answer
41 views

Does the oxidation for all the aliphatic monoaldehydes to carboxylic acids have the same value of electrode potential?

I have been wondering on this for quite a while. Consider aliphatic monoaldehydes. If I oxidize them, we get corresponding monocarboxylic acids. We can use certain oxidizing agents to perform the ...
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1answer
27 views

What is (approximately) the minimum exchange current for a potentiometric measurement?

Is there a rule of thumb for what should be the minimum exchange current to detect a certain redox couple in an aqueous solution? I would like to make a rough calculations to see whether any of my ...
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2answers
69 views

Pyrotechnic “star” without oxidizer

In the design of a celebratory pyrotechnic (firework), there exists a gunpowder explosive charge at the center of the firework and pyrotechnic "stars" lining the circumference of the explosive. The "...
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1answer
634 views

How do I determine which is the reduction reaction in a hydrogen peroxide and potassium permanganate solution?

How was it determined that $\ce{MnO4-}$ was reduction, and $\ce{H2O2}$ was oxidation? Also, why wasn’t the equation $$\ce{MnO4- + 2H2O + 3e- -> MnO2 +4OH-}$$ used? Or the $$\ce{H2O2 + 2H+ +2e- -&...
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1answer
227 views

Guidelines for when oxidation is mild and when it is strong in organic chemistry? [closed]

What are the rules, in organic chemistry, that determine whether an oxidation is mild or strong? I know that potassium dichromate is a strong oxidizing agent and it can remove two hydrogen atoms from ...
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1answer
2k views

How is a metal's relative resistance to oxidation relate to it's position in the reactivity series? [closed]

How does a metal's relative resistance to oxidation relate to its position in the reactivity series?
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1answer
4k views

Can hydrogen on platinum reduce carboxylic acids and esters?

Can $\ce{H2/Pt}$ reduce carboxylic acids and esters? I am confused about the reducing nature of hydrogen in presence of platinum. In some books, it reduces carboxylic acid and ester while in others, ...
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1answer
1k views

How to determine an unknown metal based on the reaction products with oxygen and fluorine?

The following question is, as it will probably be obvious, a homework question, however I have absolutely no idea how to progress with it beyond what I have already done. This is the question: $\pu{...
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0answers
45 views

Can Water Oxidize Cu(I) to Cu(II)

Is DI water (also without $\ce{O2}$ gas dissolved in it after degasification) a sufficiently strong oxidizer to oxidize $\ce{Cu(I)}$ in $\ce{Cu2O}$ to $\ce{Cu(II)}$ forming $\ce{CuO}$? Will this ...
5
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0answers
105 views

What makes “Color-Safe Bleach” color safe?

The ability of bleach ($\ce{NaOCl}$) to change the color of garments and introduce "bleach stains" is a well-known issue. In this question: Does bleach turn a substance white or colorless?, the ...
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0answers
128 views

Why does the electrolyte used in Lechlanché cell turn blue?

In my school there are jars which are turned into Lechlanché cells. Basically the cell has aqueous ammonium chloride solution as the electrolyte which is obviously transparent in the beginning. The ...
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1answer
454 views

Is palladium on carbon acting as an oxidising or reducing agent?

In the conversion of piperidine to pyridine, palladium on carbon (Pd/C) is used. But it is reducing agent. Clear the confusion, please.
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1answer
181 views

Reason of dissociation of water molecule in electrolysis

$\ce{H2O}$ molecule is dissociated into $\ce{OH-}$ and $\ce{H+}$ ions on reduction at cathode in electrolysis. But what happen at the atomic level to $\ce{H2O}$ that proton and hydroxide ions get ...
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1answer
725 views

What is the complete reaction for Cyanide ions reacting with Thiosulfate?

I was recently studying about the properties of Sodium Thiosulfate, where I came across the fact that $\ce{S2O3^2-}$ reacts with $\ce{CN-}$ ions to produce $\ce{SCN-}$ ions. This was quite useful in ...
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1answer
7k views

How much KMnO4 is required for the complete oxidation of ferric/ferrous oxalate in acidic medium?

Find out the amount of $\ce{KMnO4}$ required for the complete oxidation of $\pu{5 mol}$ of an equimolar mixture of ferric oxalate and ferrous oxalate. I understand that $\ce{MnO4-}$ will be oxidised ...
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1answer
269 views

Why does the stability of ascorbic acid decrease (increased rate of oxidation to dehydroascorbic acid) when pH increases?

I am doing a Chemistry IA on the stability of ascorbic acid in different pH, and found that the stability decreased (there was a lower final concentration of ascorbic acid) as pH increases. Why is ...
3
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2answers
56 views

Reduction of oxides by carbon

When reducing an oxide with carbon what would be the product? I think it would produce $\ce{CO2}$ and then the $\ce{CO2}$ would react with $\ce{C}$ to give some amount of $\ce{CO}$. For example: $$\...
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0answers
262 views

How do thiol groups act as reducing agents?

In my biochemistry practicals, we used reducing agents such as beta mercaptoethanol: and dithiothreitol (DTT) Both of these have S-H groups, and I am sure that these are involved in the reduction ...
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0answers
145 views

How do the silicon-hydrogen bonds in polydimethylsiloxane react with a H2PtCl6 catalyst

How does $\ce{H2PtCl6}$ react with $\ce{Si-H}$ to give $\ce{[PtCl4]2-}$? I know $\ce{H2PtCl6 -> 2H+ + [PtCl6]2-}$ but I'm not sure what is next. This question comes from this laboratory ...
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0answers
99 views

Could stabilized aqueous ozone be bottled to prevent half life/sanitization window?

Could stabilized aqueous ozone be bottled to prevent half life/sanitization window? Typically upon creating stabilized aqueous ozone, it has a shelf life and a sanitization window of 24 hours from ...