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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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Why is it important to use a salt bridge in a voltaic cell? Can a wire be used?

I was learning about voltaic cells and came across salt bridges. If the purpose of the salt bridge is only to move electrons from an electrolyte solution to the other, then why can I not use a wire? ...
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1answer
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Flammability (NFPA) - how is it defined?

I was reading up on a wonderful little chemical compound known as chlorine trifluoride ($\ce{ClF3}$). For a primer, check out Dr. Derek Lowe's blog post here: Sand Won't Save You This Time. The title ...
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3answers
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Why can't Pd/C and H2 reduce both the alkene and carbonyl portions of α,β-unsaturated carbonyls?

Why is it that the major product of the reduction of chalcones the ketone and not the monoalcohol? In other words, Why isn't the major product a benzyl alcohol? From what I understand, catalytic ...
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2answers
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Why do the alkali metals form different products upon combustion in air?

From Wikipedia's article on sodium: When burned in dry air, it forms primarily sodium peroxide with some sodium oxide. We know that sodium has a strong reducing capacity, so why does it produce a ...
23
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1answer
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Why doesn't the SeO2 oxidation of ketones stop at the hydroxyketone stage?

When $\ce{SeO2}$ is used to oxidise aldehydes and ketones, $\ce{SeO2}$ becomes hydrated in water, and the active reagent is selenous acid $\ce{H2SeO3}$ which oxidizes aldehydes and ketones to furnish ...
22
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2answers
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Why don't everyday things burn?

Ok, so I learned about the equilibrium constant. Now, I've seen that the equilibrium constant of burning is extremely small $(K \ll 1)$. here, I have a question. you see, $K$ is still NOT 0, which ...
22
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2answers
302 views

What is a good method to measure the redox potential of a cellular system?

I know how to measure the concentration of free thiols, which is reflective of the redox-potential of cellular compartment such as the cytoplasm or a lysosomes. What other methods exist?
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3answers
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Please explain why dioxygen difluoride is so dangerous

I just read this article that mentioned that dioxygen difluoride is very dangerous. The terms it uses are "awful", "violently hideous" and "deeply alarming". But I couldn't get a handle on exactly ...
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Why is salt needed when using vinegar to clean pennies?

Let's say you have a solution that is vinegar and it has salt (NaCl) dissolved in it. Then you place old dull pennies in it. Then you look at it 5 minutes later and the pennies are clean and looking ...
18
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6answers
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Why can't rust form without water?

Shouldn't iron oxide be able to form without water? It is just iron and oxygen. I don't really understand what the dot followed by the $\ce{H2O}$ means either. I was reading on wikipedia, but I have a ...
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1answer
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Counterintuitive Reaction of Aluminium On Steel Balls

There is a certain video which I just watched about 2 large cast iron balls. If the balls are struck together, no reaction happens, but if one is covered in aluminium foil and then struck, a large ...
18
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1answer
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Why does benzene bend in this reaction?

From here I can see why hapticity changes here, but not why it is necessary for the benzene ring to bend. The resonance energy of benzene is pretty large, and there's no balancing increase in ...
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5answers
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Iron chemistry: acetates for ebonizing wood

I have recently been “brewing” what is commonly called “iron acetate” for ebonizing wood, and I'd like to understand the chemistry of the iron/acetic acid reaction, which should be fairly simple, but ...
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Why does zinc react with sodium hydroxide?

If zinc is less reactive than sodium, then why does it still react with sodium hydroxide?
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2answers
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How can titanium burn in nitrogen?

I was going through the properties of titanium when a certain thing caught my eye: It was the reaction of burning of titanium in nitrogen. I was astonished to read it as I knew that neither is ...
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2answers
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Why is nitric acid such a strong oxidizing agent?

In my teaching-lab experiments I've seen that nitric acid solutions are able to facilitate the dissolution of metals such as silver, even though they are more active than hydrogen. Does anyone know ...
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1answer
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Migratory aptitude in Baeyer-Villiger reaction

In short, I do not understand how or why the migratory aptitude is as listed in every textbook I've read. Firstly, they talk about a positive charge being built up that is stabilised by the movement ...
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5answers
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Painting metal, does it matter if all rust is removed before?

In the context of automobile repair work, assume a metal surface has rust over it. Does it matter if all of the rust is removed before the metal surface is painted? If it does matter, then why? It ...
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1answer
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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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4answers
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How could I cause metal to rust rapidly?

I'm writing a novel set in the mid-nineteenth century. One of my characters needs to cause an iron padlock to rust rapidly, ideally within a matter of hours. The lock doesn't need to rust away ...
15
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1answer
477 views

Mechanism of dehydrogenation with nosylate

What is the mechanism of the attached reaction? How could nosylate do the dehydrogenate the species? The reaction is from this synthesis (46th IChO preparatory problem 26):
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4answers
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Do non-redox reactions exist?

Redox reaction is a type of chemical reaction, and is the result of electron transfer between chemical species. But, all chemical reactions somehow involve electron transfer! So, are there chemical ...
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1answer
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Does bleach turn a substance white or colorless?

From what I understand, bleach works to weaken the ability of a substance to absorb light. Thus this seems to be "whitening" i.e. reflecting all light. In contrast, colorlessness (according to ...
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2answers
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What is formed when you leave iron(II) sulfate in plain air?

What is formed when you leave iron(II) sulfate in plain air? Knowing that iron(II) is easily oxidised to iron(III), and assuming that the reactive component of air is oxygen, I solved it this way: $...
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2answers
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Is a highly oxidized element more electropositive than a lesser oxidized counterpart?

My issue I have a significant problem with the following excerpt from a general chemistry text: Note that ON stands for oxidation number (state). The excerpt is with regard to polyatomic anions - ...
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7answers
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Which is anode and which is cathode?

A maybe (hopefully) simple question about the denotations of "anode" and "cathode". The below image is a schematic of a polymer solar cell (Source (WBM)). (The figure text is quoted as well for the ...
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3answers
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Clear definition of a 'non-oxidizing acid'?

From the Beryllium article in Wikipedia: Beryllium dissolves readily in non-oxidizing acids, such as $\ce{HCl}$ and diluted $\ce{H2SO4}$, but not in nitric acid or water as this forms the oxide. I ...
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3answers
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Why iron reacts differently with concentrated and dilute sulfuric acid?

When $\ce{H2SO4}$ is dilute, $ \ce{Fe +H2SO4 -> FeSO4 + H2} $ and when $\ce{H2SO4}$ is concentrated, $\ce{3Fe +8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 +8H2O}$ What made the reaction with ...
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2answers
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Reaction mechanism of combustion of hydrogen

After a discussion about the usefulness of hydrogen fuel for cars with a friend of mine, I wondered what the reaction mechanism for combustion of $\ce{H2}$ was. I only study (well almost) organic ...
13
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1answer
239 views

Why is mercury a “fancy proton”?

I remember that one of my old organic chemistry profs referred to mercury as being a "fancy proton". I think it was in the context of oxymercuration reduction. What might have been his rationale for ...
13
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1answer
6k views

Why do BH3 and NaBH4 have different selectivities?

I've always known borane ($\ce{BH3}$), as a reagent for alkene hydroboration. Recently in class we talked about its use in the reduction of carboxylic acids to alcohols as well. Now obviously $\ce{...
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1answer
667 views

What are the practical differences between the various DMSO oxidations (Swern, etc.)?

Recently, I was reading a paper about a total synthesis of (+)-rubriflordilactone A (the article is open access: Angew. Chem. Int. Ed. 2015, 54 (43), 12618–12621). In two different steps where an ...
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2answers
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What is the mechanism of the Clemmensen reduction?

I have learned that we can reduce a ketone to an alkane using the Clemmensen reduction, where we treat the ketone with amalgamated zinc in the presence of $\ce{HCl}$. But my book didn't mention the ...
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2answers
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What is the strongest oxidising agent?

I searched for the strongest oxidising agent and I found different results: $\ce{ClF3}$, $\ce{HArF}$, $\ce{F2}$ were among them. Many said $\ce{ClF3}$ is the most powerful as it oxidises everything, ...
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2answers
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HI/P reduction mechanism

I recently answered a question about Breaking Bad's initial methamphetamine production method (i.e. the reduction of (pseudo)ephedrine). The reaction is as follows: (Source) It is infamously known ...
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2answers
395 views

Why do oxidation numbers work?

I understand that oxidation numbers are a method for keeping track of electrons in a reaction and how they are generally assigned (electrons in a bond are assigned to the more electronegative atom). ...
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1answer
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How many hydride ions are available in NaBH4?

Different sources have different answers. In the reduction of an aldehyde or ketone to an alcohol by Sodium Borohydride, how many moles of aldehyde are reduced by one mole of Sodium Borohydride? ...
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3answers
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Reduction of α,β-unsaturated nitro compounds

Would it be possible to reduce a α,β-unsaturated nitro compound to a saturated amine using for example $\ce{NaBH4}$? I know these kind of compounds will be reduced by hydrogenation using a $\ce{Pt/C}$ ...
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1answer
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Purpose of ammine in Tollens' reagent

In this previous question the mechanism for the reaction of Tollens' reagent was outlined. As I understand it the oxidising agent in Tollens' is the diamminesilver(I) complex $\ce{[Ag(NH3)2]+}$ but ...
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1answer
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Why does HNO3 not give off H2 when reacting with Cu?

A dilute solution of which acid is most likely to produce a reduction product other than $\ce{H_{2}}$ when it reacts with a metal? (A) $\ce{HF}$ (B) $\ce{HCl}$ (C) $\ce{HNO3} $ ...
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7answers
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Does NaOH react with K to form NaOK or KOH?

I realized that the $\ce{-OH}$ group when it reacts with some metal like $\ce{Na}$ or $\ce{K}$ will replace the $\ce{H}$ element to form $\ce{-OK}$ or $\ce{-ONa}$: \begin{align} \ce{H2O + Na &...
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3answers
241 views

Would it be possible to produce a non-toxic atmosphere using a coal fire and frozen oxygen?

A Pail of Air is a classic science fiction short story by Fritz Leiber from 1951 describing how a family survives on an Earth that has left its orbit around the sun, using desparate low-tech methods: ...
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1answer
675 views

Why is KI oxidized by H2SO4, whereas NaBr isn't oxidised?

My textbook says that alcohols react with sodium bromide and sulphuric acid to form the corresponding alkyl bromides. At the same time they also mention that sulphuric acid mustn't be used with ...
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2answers
229 views

Dissolving metal reductions

Could reduction of an organic compound by reacting it with sodium dissolved in $\ce{NH3}$ still proceed if a metal such as aluminium were used instead of sodium? I'm not sure about the aluminium amine ...
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1answer
764 views

Is it possible for Cu to reduce Cu2+?

I tried a slightly different set up of a Galvanic cell by inserting the $\ce{Zn}$ electrode into the $\ce{CuSO4}$ solution and the $\ce{Cu}$ electrode into the $\ce{ZnSO4}$ solution. This gave a ...
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4answers
2k views

How much ozone is produced by ionization of air and how turn ozone into oxygen

I want to make a plasma speaker. I'm worried about the amount of ozone being produced by the ionization of the air and it possibly not being a safe amount. Even if it doesn't produce a dangerous ...
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3answers
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Why is standard reduction potential an intensive property?

My book says that Since the number of electrons lost must equal the number gained, the half-reactions must be multiplied by integers as necessary to achieve the balanced equation. However, the ...
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2answers
6k views

What does the phrase “reducing atmosphere” mean in quantitative terms?

There is a debate about "how reducing" the atmosphere of the early Earth was, and this question is my attempt to grasp toward an understanding of what that that phrase really means. As a bit of ...
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2answers
11k views

What is the product of a copper and vinegar reaction?

I put a copper wire through a hole in the cap of a water bottle, filled the water bottle ~ half way full with vinegar, and left it over night. The part of the wire inside the bottle that wasn't in ...
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2answers
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Difference between Lindlar and Rosenmund catalysts

Is there any difference between the Lindlar and Rosenmund catalysts? I've checked around, and it seems the same compounds are used to make both. Is there a difference in their reactivities or are they ...