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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Disproportionation Reactions of the Halogens: Writing balanced net ionic equations for four reactions. See details

I first conducted the following reactions, each in separate test tubes: $\ce{NaBr}$ + $\ce{H2SO4}$ + $\ce{NaBrO3}$ $\ce{KI}$ + $\ce{H2SO4}$ + $\ce{KIO3}$ ...with water and dichloroethane added to ...
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Effect of side reactions on galvanic cell using iron rod as anode and sodium chloride as salt bridge

We just made a galvanic cell on a chemistry lesson using iron, iron sulfate , copper and copper sulfate. We used a sponge soaked in $\ce{NaCl}$ solution as the salt bridge. The issue is that we ...
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1answer
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What product is created in a zinc - nitrate reaction? [closed]

Question: Place 2 mL of Nitric acid in a test tube and add a small piece of Zinc turning I thought that the overall net ionic equation would be: $$\ce{Zn + 2H+ -> Zn^2+ + H2}$$ Is this correct? ...
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Why is in the reaction of cyclic unsaturated aldehydes with hydrazine and hydrogen peroxide the aldehyde preserved?

Question What is the product of this reaction? The answer given: At first, I thought this was a typical Wolff-Kishner reduction, but then I saw the reagents didn't match up (no $\ce{OH-}$...
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Oxidizing properties of sulfuric acid: can it oxidize hydrochloric acid to chlorine?

Can $\ce{H2SO4}$ oxidize $\ce{HCl}$ to $\ce{Cl2}$? I know that $\ce{KMnO4}$ can do it, but my question is considering $\ce{H2SO4}$. In sulfuric acid, sulphur is in +6 oxidation state and in $\ce{KMnO4}...
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Average Oxidation State - Utility?

What is the purpose of calculating an average oxidation state for a certain element in a compound? Hence the “average oxidation state” of carbon in acetic acid is 0. And the oxidation state ...
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How does iron rust in basic conditions?

I performed an experiment about the corrosion of iron. I used acid and base in the experiment. I understand that the acid speeds up the corrosion of iron. But I don't understand why the base also ...
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Temperature at which the reaction Oxalic acid + KMnO4 becomes autocatalytic

As described many times, the reaction between oxalic acid and potassium permanganate can be autocatalytic due to the production of Manganese ions. I've read that this only occurs at higher ...
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Half equations for H2O2 for its reducing and oxidising nature in acidic and alkaline medium

Is there a complete list of all the half equations for $\ce{H2O2}$ - both oxidation and reduction, in acidic and alkaline conditions? I've looked on the internet but can't seem to find a list with all ...
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Are there stronger oxidizing agents than fluorine gas?

Are there stronger oxidizing agents than fluorine gas, so it could oxidize fluoride to fluorine? Also, in case of oxygen, fluorine gas can oxidize oxygen gas to the exotic dioxygenyl ion. Can ...
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Why would electrode be positively charged in electrolysis?

From my understanding, a battery provides a driving force to pull electrons from the anode, thus the anode becomes positively charged. Suppose the anode is copper, the process should be as follows: $\...
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Will potassium permanganate react with ferric chloride?

I came across a question : Which of the following compound does not decolourise an acidified solution of $\ce{KMnO4}$? Answer was: After doing a bit of research I found that $\ce{KMnO4}$ oxidises $\...
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Why should the redox reaction happen between the copper ions and iron atoms?

I know that when $\ce{Cu^{2+}}$ ions react to $\ce{Fe}$ atoms, it becomes $\ce{Cu}$ + $\ce{Fe^{2+}}$. My question is, why? Copper atoms normally have 29 electrons. This means that in the K-shell there ...
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What is the first ionization energy of the hydride ion?

What is the first ionization energy for hydride? Since there are two electrons in the s orbital, I suppose it should be more stable than hydrogen, despite the extra electric charge, so the ionization ...
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Comproportionation reactions

Is the following reaction a comproportionation reaction? $\ce{NH4NO3 -> N2O + H2O}$ The wikipedia definition says: Comproportionation or synproportionation is a chemical reaction where two ...
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Does lead(II) chloride dissociate into Pb²⁺ and Cl⁻ ions in HCl?

While solving JEE Advanced 2020 (Paper 2) questions, I came across this particular question: Q.10 Choose the correct statement(s) among the following. (A) $\ce{SnCl2 · 2 H2O}$ is a reducing agent. (B)...
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What products are formed when KMnO4 and KI react with each other in “weakly basic” medium?

While solving JEE Advanced 2020 (Paper 2) questions, I came across this particular question: According to the final answer key, its answer is 6. In my chemistry book (NCERT Chemistry), the following ...
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Oxidation of naphthalene with KMnO4

What is the product when naphthalene is oxidized by alkaline (or acidic) solutions of $\ce{KMnO4}$? Some possible reactions show up in a google search, but they have no references: Naphthalene to ...
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Why are the sulfide ores generally converted to an oxide and then reduced? [closed]

In the elementary extraction of metals from their concentrated ores, why is the ore generally converted to an oxide, and then reduced? Why is the reduction of these metal oxides easier than the other ...
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Redox reaction: Iron(III) and Iodide ion [closed]

I'm a real beginner in chemistry and I'm currently reading about redox reactions. I'm quite confused about this simple redox reaction: ${\text{Iron(III) ion + Iodide ion} \rightleftharpoons \text {...
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Why thermal decomposition of iron(II) nitrate and sodium nitrate yields different products?

\begin{align} \ce{4Fe(NO3)2 &-> 2Fe2O3 + 8NO2 + O2}\tag{1} \\ \ce{2NaNO3 &-> 2NaNO2 + O2}\tag{2} \end{align} Why do nitrates of different metals decompose in different ways? Why do ...
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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 on 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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If the ferric ion is more stable than the ferrous ion, then why is it readily reduced to the latter?

The standard reduction potential value for the ferric ion: \begin{align} \ce{Fe^3+ + e- &<=> Fe^2+} & E^\circ &= \pu{0.77 V} \end{align} The value is positive, hence it means that ...
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Iron-II to iron-III change in complex formation

We have an iron dust sample, which is treated with hydrogen chloride in aqueous solution. The solution enters in a reaction with a sodium hydroxide powder, from which we obtain a precipitate. Could we ...
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Is it the solution energy or the reduction potentials (or both) that drives a galvanic cell?

I have received conflicting explanations for why the redox reaction in a galvanic cell occurs. Explanation 1: Some say that it occurs because the anodic metal dissolves more easily than the cathodic ...
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1answer
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Balancing redox reaction of zinc and hot diluted nitric acid

I need to balance the following reaction: $$\ce{Zn + HNO3 -> Zn(NO3)2 + NH4NO3 + H2O}$$ I assigned all oxidation numbers: $$\ce{\overset{0}{Zn} + \overset{+1}{H}\overset{+5}{N}\overset{-2}{O_3}\...
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1answer
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Why did we introduce the concept of oxidation number in chemistry? [duplicate]

Isn't oxidation number a weird concept? It assumes complete transfer of an electron from a more EN to a less EN atom per covalent bond formed. This assumption isn't even true. We know that partial $δ^+...
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199 views

Reduction of copper oxide by hydrogen

In the concluding part of my previous question, wouldn't there be an explosion near the hole in the tube from where the excess hydrogen is coming out instead of a steadily burning flame?
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How to convert cell diagram to a chemical equation?

How would one convert on the right side of the cell diagram: $$\ce{Zn(s) | Zn^2+(aq) || MnO4-(aq), Mn^2+(aq), H+(aq) | Pt(s)}$$ $$ \begin{align} \ce{Zn(s) &-> Zn^2+(aq)} \tag{ox}\\ \ce{MnO4-(aq)...
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At what concentration would copper sulphate crystallise at 25 degrees Celsius?

I am doing an experiment on how increasing concentration of copper sulphate affects the voltage in a galvanic cell. The voltage increased as temperature did until 2M where it started to decrease. I ...
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1answer
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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 ...
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Reasoning for redox reactions to be classified as such

Could anyone help me out solving this question regarding redox reactions? I am fairly new to this topic. Which of the following is a redox reaction? (1) $\ce{NaCl + KNO3 -> NaNO3 + KCl}$ (2) $\ce{...
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Adjusting redox reactions

$$\ce{KCl + KMnO4 + H2SO4 -> K2SO4 + MnSO4 + H2O + Cl2}$$ Attempt. I want to adjust this redox reaction, I've figured out that Chlorine and Manganese are the 2 elements that change thier oxidation ...
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Does 50% hydrogen peroxide dissolve gold?

We have seen that the silver electrodes on a piezo element are being seemingly dissolved by exposure to our mixture of $50\,\%$ hydrogen peroxide. I was wondering if we were to switch to gold ...
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1answer
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Copper plating with electrolyte not working (Cu(OH)2 vs CuSO4)

I've been experimenting using electroplating, and I recently made a solution by placing two copper pieces connected to a voltage source, in water. I suspect that this created copper(II) hydroxide, as ...
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893 views

What is the role of hydration enthalpy in oxidation?

My textbook says that the greater oxidising behavior of fluorine than chlorine can be attributed to the high hydration enthalpy of $\ce{F-}$ ions and the low dissociation enthalpy of $\ce{F-F}$ bond. ...
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How do I write a balanced redox reaction for the oxidation of chalcocite [(Cu2S) (s)] by O2 (g) to form Cu2+ (aq) and SO42- (aq) [closed]

I'm not exactly sure how to get the oxidation and reduction half reactions. Any help will be much appreciated!
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How do acids prevent ferrous sulfate from getting oxidised?

If $\ce{FeSO4.7H2O}$ is dissolved in an acidic environment, for example in 0.05 M aqueous solutions of methanoic or ethanoic acid, would that prevent it from getting oxidized if an oxidizing agent ...
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Can you calculate the oxidation potential of an ion?

Is there any way to calculate the oxidation potential of [Fe(OH)(H2O)5]+? I am unsure if it can be done since I have only seen oxidation potentials provided for specific reactions of single elements, ...
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Balancing redox reactions

This has gotten me confused since long. Not all equations have clean half- reactions, some cations are in more than one compound while some anions are in some other compounds. Some reactions don't ...
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1answer
298 views

Ordering the reduction potentials for Cr3+, Mn3+ and Fe3+?

I have been asked to order, with explanation, the standard reduction potentials for the following: $\ce{Cr^3+ + e- -> Cr^2+}$ $\ce{Mn^3+ + e- -> Mn^2+}$ $\ce{Fe^3+ + e- -> Fe^2+}$ (all ions ...
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Question regarding the colour of Benzoic acid and Benzyl alchohol

This question is primarily based on the Cannizzaro reaction, where a base induces a disproportionation reaction of non-enolizable aldehydes (benzaldehyde, formaldehyde, etc) to form an alcohol and a ...
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2answers
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Why transition metal chloride complex have lower reduction potential than metal aqua ions?

Why transition metal chloride complex have lower reduction potential than metal aqua ions? For example: $$ \begin{align} \ce{Au^3+(aq) + 3 e- &-> Au(s)} &\quad E^\circ &= \pu{+1.52 V}\...
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1answer
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Why does green ferrous sulfate solution change color to yellow upon addition of hydrochloric acid?

I was demonstrating the formation of $\ce{Fe(OH)2}$ precipitate at school when the light green $\ce{FeSO4}$ I was using reacted with dil. $\ce{HCl}$ turned yellow. This only happened with dil. $\ce{...
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1answer
903 views

Wurtz reaction on acidic compounds

Why can Na not be used for the Wurtz reaction of compounds having an acidic group like alcohol or carboxylic acid?
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Determining iron content by titration

The redox reaction is $$\ce{KMnO4-(aq) + 8 H+(aq) + 5 e- -> Mn^2+(aq) + 4 H2O(l)}.$$ Where does $\ce{H+}$ come from in this reaction? What happened to $\ce{K+}$ in potassium permanganate?
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How does the addition of NaCl to the cathode side effect the potential of a voltaic cell: Zn(s) | Zn2+(aq) 0.1M || Cu2+(aq) 0.1M | Cu(s)

By addition of $\ce{NaCl}$ to the $\ce{Zn}$ side of the cell, I observed precipitation of $\ce{ZnCl2}$. I measured the voltage to $\pu{1.05 V}$ before adding $\ce{NaCl}$ to the cathode side, I then ...
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How to predict the outcome of a crossed Cannizzaro reaction?

My question is, how do we predict the products of a cross-Cannizzaro disproportionation in presence of a concentrated base? i.e, How to judge which of the aldehydes (both don't have any alpha hydrogen)...
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362 views

Are aqueous solutions of oxidizing agents safe? [closed]

In the "reducing agent" article in Wikipedia it says Good reducing agents are reagents that deliver $\ce{H2}$. Wouldn't that make water unsafe to dissolve oxidizing agents?
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What does onset of oxidation mean in Cyclic volammetry

I've read a few posts on here on how to calculate onset of oxidations in Cyclic voltammetry. However, I dont know what it actually means when comparing the onsets of oxidations of two different ...

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