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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Electrochemistry - reduction potentials - an IB Chemistry Question [closed]

I have re-read the Electrochemistry chapter from my textbook just now to remind my self of the exact formulae. I still don't understand how to approach this question, however - how can we work it out? ...
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1answer
35 views

How does precipitate affect cell potential?

A cell is set up with copper and lead electrodes in contact with $\ce{CuSO4(aq)}$ and $\ce{Pb(NO3)2(aq)},$ respectively, at $\pu{25 °C}.$ The standard reduction potentials are: $$ \begin{align} \ce{Pb^...
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1answer
19 views

What happens at the inert anode in an electrolytic cell?

Recently I did an experiment using graphite as the anode and iron as the cathode for an electrolytic cell. I tried plating different metals such as copper, nickel, and zinc with CuSO4, NiSO4, and ...
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How does the value of standard electrode potential affect a metal-ligand complex to be formed?

Could someone please explain on how the value of standard electrode potential affects the ability of metal ions to form a ligand complex with water?
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What Do Halide Tests Mean?

In school, we need to react various halides with silver nitrate and see if they form a precipitate + which color. We then need to add ammonia to see if they dissolve. For example, Sodium Chloride, ...
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In dative bond S→ S, why are the Oxidation state of donor S = +2 and recipient S= -2 although both of them have the same electronegativity?

We know that if the dative bond is directed towards less electronegative element, it is ignored while calculating the oxidations state and it is considered as +2 for donor and -2 for the recipient ...
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35 views

What is the O.N. of S in Na2S2O3 where S are in dative bond with eachother? [duplicate]

Actually,in above compound, S atom has a dative bond with another S atom. My question is in such case of dative bond between similar electronegative atoms,how can a donor atom may have +2 O.N. and ...
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2answers
112 views

Origin of electrode potential and its connection with electric double layer

Recently, I was learning about electrode processes and I came across the topic of "electrode potentials". I understood that at equilibrium, a potential difference was generated at the ...
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70 views

What do ε₀ and V mean in a Pourbaix diagram?

From Wikipedia: What does this graph mean? What is $\varepsilon$? It looks like $\varepsilon_0$, like the vacuum permittivity, but what does this have to do with the polymorph and/or isomers of ...
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1answer
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Do I have to systematically show the protons in my reaction equation to find the Pourbaix diagram's line equations?

I was trying to get the line equation for the Pourbaix diagram for the couple $\ce{Ni(OH)2}/\ce{Ni}.$ I can write two chemical equations for basic and acidic conditions, respectively: $$ \begin{align} ...
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What reaction is used for calculating pH of the solution obtained after ethanol oxidation with potassium permanganate?

If $\pu{30.0 ml}$ of $\pu{0.20 M}$ ethanol solution reacts with $\pu{1.80 g}$ potassium permanganate, what will be the final $\mathrm{pH}$ of the solution? Assume a complete reaction and that only the ...
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How efficient is Zinc Acetate as an Oxygen absorber?

I used to work in a microbiology lab and they used zinc acetate as O2 absorber for the anaerobic chamber. Was this an efficient way to scrub O2 from the air? I am asking because I want to make an N2 ...
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Why do we need weak or strong acids to displace the anions of other weak acids from salts?

I have already looked at Why does a strong acid displace salt of weak acid? but I couldn't understand the answer and the analogy there. And I mean the above question in the following context : $\ce{...
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Writing reaction from cell notation

$$\ce{Ag}|\ce{AgBr (s) ,KBr}||\ce{AgCl (s) ,KCl}|\ce{Ag}$$ I know that from the above cell notation, we can write the reactions as $$\ce{Ag}\rightarrow \ce{Ag+} +\ce{e-} \hspace{30pt} \text{(anode ...
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Why do nitrogen-containing organic compounds give N2 as the combustion product?

My teacher gave the explanation stating that consider that first the nitrogen in lower state is oxidised to $\ce{N2}$ and then the further oxidation would stop as the $\ce{N-N}$ bond energy of $\ce{N2}...
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51 views

Balancing complex redox reaction of gold treated with sodium cyanide

How would you balance this reaction: $$\ce{Au(s) + NaCN(aq) + O2(g) + H2O(l)-> Na[Au(CN)2](aq) + NaOH(aq)}?$$ Here’s what I’m came up with. First we can balance any atoms besides hydrogen and ...
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Are these reactions redox reactions? [closed]

I'm supposed to tell whether the following are redox reactions. (1) K+ + H2O --> KOH + H2O (2) Cu + 2AgCl --> CuCl2 + 2Ag I tried listing out the oxidation numbers for each element in both ...
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1answer
67 views

What does the salt actually do during electrolysis?

Pure water does not conduct electricity. When you dissolve a salt like $\ce{Na2SO4}$ in water the solution becomes a better conductor. If electrolysis is done on this solution, oxygen and hydrogen ...
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1answer
653 views

Why isn't my electrochemical cell producing its potential voltage

For a school project, I am testing how concentration affects the voltage output of three metals. So I am building voltaic cells with 0.1 M copper nitrate and 0.1 M, 0.01 M, and 0.001 M of zinc, ...
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Elimination vs reduction reactions - how to tell

Here are two compounds: Compound H: and compound I: Compound H reactions with the reagent shown below to form compound I and two other products. How would you clarify this reaction? I thought it was ...
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321 views

How to refine manganese metal from manganese(IV) oxide found in batteries? [closed]

I opened up some lantern batteries, and inside there's $\ce{MnO2}$ powder, carbon rods, and zinc casings, and other stuff that I don't know what it is exactly. I scraped out $\ce{MnO2}$-containing ...
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77 views

Thinking of reducing aluminum hydroxide with magnesium

Is it possible to reduce aluminum hydroxide to aluminum metal by using a sacrificial magnesium electrode in a single displacement reaction? I checked my revision of redox charts and it looks like it ...
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Why doesn't NASA or SpaceX use ozone as an oxidizer for rocket fuels?

Presumably, it would be expensive to use ozone ($\ce{O3}$) as an oxidizer instead of $\ce{O2}$, but would the extra oomph be worth it? Does $\ce{O2}$ provide as much thrust/energy/heat as can be ...
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Why can't nitrate ion in aluminium nitrate solution oxidise copper when a copper spoon is used to stir the solution?

I have been recently studying electrochemistry and I came across the electrochemical series. A question was asked saying what will happen if a copper spoon is used to stir an aluminium nitrate ...
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1answer
46 views

Conditions for spontaneity of redox reaction among redox couples with equal standard reduction potentials

A question from the university course: Could a redox reaction spontaneously occur among the redox couples $\ce{A_{ox}}/\ce{A_{red}}$ and $\ce{B_{ox}}/\ce{B_{red}}$ within non-standard circumstances ...
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787 views

What are high-energy electrons?

I read that (in cellular respiration) the transported electrons in NADH have a higher energy than those in FADH2. I can't find a (simple or otherwise) explanation of what a "high-energy" ...
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1answer
52 views

Lost track of the hydrogen in step 3 of the Krebs cycle

I'm trying to follow the Krebs cycle step by step, accounting for the number of hydrogens in each molecule before and after reactions. I've run into a problem starting from step 3. Isocitrate has ...
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70 views

Which of the following is the strongest oxidizing agent?

Which of the following is the strongest oxidizing agent? A) $\ce{I2}$ B) $\ce{Ag^2+}$ C) $\ce{Cu^2+}$ The answer is apparently B) but I think it has to be A) because it is the only non-metal which ...
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1answer
33 views

Balancing redox equation involving ethanol and dichromate ion [closed]

$$\ce{C2H6O(l) + Cr2O7^{2-}(aq) -> C2H4O2(aq) + Cr^3+(aq)}$$ Basically, I have written the half equations, but I have having trouble with converting ethanol to acetic acid ($\ce{C2H6O -> C2H4O2}$...
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25 views

Driving force of Galvanic cell

Work can be extracted from galvanic cell which has a negative Gibb's free energy. I was wondering what is the driving force of it: I would naturally think its the Gibb's free energy, but the gaps ...
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2answers
67 views

How do I prevent oxygen interfering when I prepare a FeCl2 solution from anhydrous FeCl2 powder?

I have a bottle of anhydrous $\ce{FeCl2}$ powder (from here; it is 98% pure and was kept in a glovebox after opening it for the first time to minimize reactions with oxygen) and want to make this into ...
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1answer
73 views

Acidic KMnO4 oxidizes H2S to S. Why doesn't the oxidation proceed further to sulfur oxide, sulfur dioxide or sulfur trioxide?

I have some idea about the question. I think it has to do with oxidation/reduction potentials but I am not able to find any resource for the exact values or how to make sense of them in this context. ...
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1answer
50 views

Will a gold coin react with an aqueous magnesium nitrate? [closed]

I really have no work to show, I don't even know how to approach answering this... so if someone can push me in the right direction, thanks. But I did have the idea that it might have something to do ...
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1answer
47 views

How does Metol (4-(methylamino)phenol sulfate) react when developing black and white photos? [duplicate]

I know that during the development process the developing agents reduce exposed Ag ions to silver. But what happens to Metol which is one of the developing agents?
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3answers
79 views

How to balance the reaction between ethanol and chlorine using oxidation number method?

Balance the following chemical equation using oxidation number method: $$\ce{C2H5OH + Cl2 -> CHCl3 + HCO2- + Cl- + H2O}~\text{(In basic medium)}$$ Chlorine in $\ce{Cl2}$ is in oxidation state $0$ ...
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What does a sigmoidal and non-sigmoidal shape of a oxygen reduction reaction (ORR) voltammogram mean?

While testing materials for their ORR performance, one can encounter linear sweep voltammograms that have a well defined diffusion plateau and a good sigmoidal shape. On the other hand, the opposite ...
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1answer
79 views

How is indigo carmine used in Lowenthal-Permanganate titration as a redox indicator?

In a Lowenthal-Permanganate titration, cider tannins are quantified by titrating the cider with indigo carmine indicator and sulfuric acid against potassium permanganate. Tannins are antioxidants, so ...
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1answer
44 views

Redox and anode/cathode in lead acid battery

I have watch a video about lead acid battery and I am very confused about the way the half reactions are labelled. I have learned that oxydation is the loss of electron (so it's the half reaction with ...
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1answer
59 views

How do I go about solving this question? [closed]

So I've studied Redox concepts but in the exam we are asked questions like these. How am I supposed to know what the reaction is going to be? How do I go ahead and assume what oxidation state it's ...
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27 views

How does the Benedicts Test work? [duplicate]

What exactly is the mechanism by which Benedict’s test works for reducing sugars? As I understand it the free hemiacetal groups on reducing sugars opens up and an aldehyde is formed, this is then ...
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44 views

What makes concentrated aqueous solutions of aluminium nitrate and aluminium chloride suitable to dissolve noble metals, specifically gold? [closed]

Aluminium nitrate is a strong oxidising agent and aluminium chloride acts as a Lewis acid. Also these solutions are claimed to have the abilities of aqua regia and therefore can dissolve noble metals. ...
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1answer
63 views

Why can't iodide be oxidised to iodate in acidic medium?

Even if we use a strong oxidising agent like 'permanganate ion in acidic medium' it doesn't help oxidise iodide to iodate, but a relatively weaker oxidising agent 'permanganate ion in alkaline medium' ...
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3answers
829 views

What is the equation for the reduction of water? [closed]

I'm a grade 12 student trying to understand redox reactions. What's the equation for the reduction of water? The back of my textbook says: $\ce{2H2O + 2e- -> H2 + 2OH-}$ I get that this makes sense,...
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20 views

When MnO2 acts as a catalyst to speed up the decomposition of H2O2 what does it actually do? [duplicate]

Everywhere I look it just states that $\ce{MnO2}$ acts as a catalyst but I have yet to find a simple explanation for what it actually does. What is the mechanism involved in simple terms?
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38 views

Write half-cell reaction for a battery

A primary battery has the reaction: $$\ce{2MnO2 + Zn + 2NH4Cl -> Mn2O3 + Zn(NH3)2Cl2 + H2O}$$ Write the half-cell reactions for the given equation. I am having trouble understanding how you know ...
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1answer
36 views

What (stored-as-solids) acids/liquids can clean corroded copper?

I'm looking for a liquid that can remove copper corrosion (oxides and basic carbonates - the black and green stuff) off copper piping. The corrosion will be located on the inside of the pipe, in hard-...
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41 views

What reaction would take place on an electrode in a secondary cell if it were charged and the other electrode removed?

I'm reading a book that covers the basics of electrical theory and I'm at a chapter that discusses the concept of a secondary cell. The author includes the redox reactions that take place in a primary ...
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33 views

After neutralizing a free radical, why don't anti-oxidants become free radicals themselves?

This is my understanding: A free radical is a molecule with a single unpaired electron. This molecule is highly reactive because it wants to steal an electron from another molecule (oxidation). Anti-...
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2answers
67 views

Calculating the cell potential of a half cell from two half cell equations [duplicate]

I understand the premise of the question and how to solve it but I don't quite understand why I'm a factor of 2 out: Construct a potential diagram (at $\mathrm{pH} = 0$) for the reduction of aqueous $...
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1answer
202 views

Oxidation of alcohols by Ceric Ammonium Nitrate

I have realized that reaction with ceric ammonium nitrate essentially results in coordination of alcohol with $\ce{Ce(IV)}$ and my teacher referred that we should be able to proceed it to form ketone ...

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