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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3
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1answer
3k views

Vertical lines in a Pourbaix Diagram

I know that because of the absence of the hydrogen ions in a reaction ($n_{H+} = 0 $) , the correspondent E-ph line have to be horizental , but what exactly the types of reactions (if there is) that ...
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Electrolysis of aqueous copper (II) nitrate

There are two copper blocks sitting in the $\ce{Cu(NO3)2 (aq)}$ solution, a battery is attached onto both of them, providing enough energy to start the reaction. Since solid pieces of copper are ...
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Extraction of Sn from SnO2

In the extraction of $\ce{Sn}$ from $\ce{SnO2}$ by carbon reduction method, why is $\ce{CO}$ formed instead of $\ce{CO2}$ as per the following reaction? $\ce{SnO2 + C -> Sn + CO}$
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Why does ammonia act as an acid in only the first of these two reactions?

$$\ce{2Na(l) +2NH3 (g) ->2NaNH2(s) + H2(g)}$$ $$\ce{CH3Cl (alc) +NH3 (alc) -> CH3NH2 (alc) +HCl(alc)}$$ Doesn't ammonia donate a proton in both cases?
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Balancing redox reaction with one reactant

Consider the following acidic reaction: $\ce{As -> H2AsO4- + AsH3}$ How would I go about balancing this using the half reaction/ion-electron method?
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933 views

Which reaction between Lugol and Hydrogen peroxide?

The Lugol solution is a mixture of $\ce{(K+, I- )}$ and $\ce{I2}$ such that $\ce{I3-}$ are formed by: $$\ce{I- + I2 -> I3-}$$ I know that the brown color comes from $\ce{I2}$, but in this ...
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Redox reaction terminology

In the case of this redox reaction: $ \ce{ Cu SO_4 + Zn → Zn SO_4 + Cu} $ Is it correct to say that the sulfate reduces to the zinc? Or is it the whole molecule that is reducing? Or just the copper? ...
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324 views

Prediction of ionic reduction?

Here are some standard electrode potentials:- $$\ce{SO_4^{2-} + 4H^+ + 2e^- -> SO_2 + 2H_2O}\\E^o=0.17\mathrm{V}\\ \ce{NO_3^- + 4H^+ + 3e^- -> NO + 2H_2O}\\E^o=0.97\mathrm{V}\\ \ce{NO_3^- + ...
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What's the technical term for supercharging an acid with an oxidizer? And does it always work?

In a recent Mythbusters episode, where they tested some Breaking Bad chemistry assertions, they debunked the hydrofluoric acid body-dissolving myth referenced elsewhere in Chemistry.SE in the question ...
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Can carboxylic acids be oxidised further?

I know that compounds like alcohols can be further oxidized to aldehydes (or ketones) and to carboxylic acids. But, is carboxylic acid the best oxidized form of a given compound? What happens when ...
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What is the net ionic equation for rection of liquid bromide with sodium iodide crystals?

I have this problem, Liquid bromine is added to a container of sodium iodide crystals I interpreted it with this molecular formula $\ce{Br_{2(l)} + 2NaI_{(s)} \rightarrow 2NaBr_{(s)} + I_{2(g)}}$. ...
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How to determine an oxidation number of an atom in the compound, that has at least two elements, which are not hydrogen or oxygen?

Wiki says: [Oxidation state] is defined as the charge an atom might be imagined to have when electrons are counted according to an agreed-upon set of rules: The oxidation state of a free ...
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Shift of the null half-reaction potential

If we change the null half-potential, would it change half-potentials of other half-cell reactions by the same amount, so that voltages of net reactions stay the same?
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Finding one of the two unknown potentials with a given voltage of a net reaction

A half-cell consisting of palladium rod dipping into a $1\ M$ $\ce{Pd(NO_3)_2}$ solution is connected with a standard hydrogen half-cell. The cell voltage is $0.99\ volt$ and the platinum electrode in ...
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1answer
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Balancing the equation when MnO₂ is reduced to MnO by H₂(g)

I am studying for a final tomorrow and I was going through some problems on older exams and came across one which I wasn't really sure how to solve. The problem is to write the balance equation when: ...
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Electrode potentials at interfaces?

My questions relates to the fundamental concept of electrochemistry, more specifically the electrode potentials. 1) First, why is there a potential difference at the interface of two phases? ...
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Why does chlorine undergo disproportionation in alkaline media?

One reaction used to form sodium hypochlorite (A type of bleach) is as follows: $\ce{2NaOH(aq) +Cl2(g)->NaOCl(aq) + NaCl(aq) + H2O(l)}$ Provided the sodium hydroxide is dissolved in some ...
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253 views

Oxidation number and Pourbaix diagrams

In a Pourbaix diagram (E-pH diagram) where the regions are given , but the assignment of these to the elements we have is not done yet , how can the oxidation numbers helps me out assigning each ...
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Reaction of an electrode

Why is the cathodic reaction of $I^-/AgI/Ag$ is $$\ce{AgI + e- -> Ag + I-}$$ but not, $$\ce{Ag+ + e- -> Ag }$$ whereas, in $Ag/AgCl(s)$, $KCl$(0.2M); it is $$\ce{Ag+ + e- -> Ag}$$
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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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speeding up etching process of a copper board

Background: I use Sodium persulfate to etch a copper board to manufacture home made Printed Circuit Board (PCB). On the etching powder's plastic, it is written that: 1.5-2dl of etch powder in 1 ...
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What is this brown liquid that I got when I boiled glycerol and water solution?

I boiled a solution of glycerol and water at about 160 degree Celsius and got a brown liquid much less in volume (boiled off the entire water I think; also not so sure about the accurate temperature). ...
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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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Cathodic protection of aluminium

I am planning an experiment for a chemistry class about corrosion. I am going to show how different prevention methods affects the corrosion of iron and aluminium parts using bleach as the oxidizer. ...
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Identifying Reaction Types

I need help on identifying precipitation, acid-base, and redox reactions. I know what each one is in theory: Precipitation: Creating a solid Acid-Base: neutralization Redox: exchange of electrons ...
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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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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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Solving carbon black

I want to remove a layer of 2 mm thick carbon black on a copper bowl on the outside from hanging over wood and coal fire. I have tried different solvents, but the carbon seems to be very resistive. ...
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Reduction by thermionic electrons

Certain reduction reactions require electrons as reducing agents. Is the overlapping of orbitals is necessary for electron transfer? I mean if a element $\ce{X}$ is heated and it gives out thermionic ...
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How many electrons are transferred in this redox reaction?

I have the following reaction: $$\ce{CH_4 (g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2 O(l)}$$ How do I determine how many electrons are transferred in this reaction? More specifically, I need to know ...
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Why do sodium halides react so differently with sulfuric acid?

Why do sodium halides react so differently with sulfuric acid? \begin{align} \ce{NaF + H2SO4 &-> NaHSO4 + HF} \tag{1a}\label{NaF}\\ \ce{NaCl + H2SO4 &-> NaHSO4 + HCl} \tag{...
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659 views

Electrochemical Cell

Now in an electrochemical cell , we make use of the fact that whenever there is a potential drop , electrons will flow from lower to higher potential as for a potential drop , there must be an ...
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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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Where do the rate laws for the Chlorine Dioxide-Iodine-Malonic Acid reaction come from?

After reading a section on this particular oscillatory reaction, something started bugging me about it. However, let me lay out the basis of my question. From what I've researched, Lengyel and ...
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2answers
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Writing the net reaction for reaction of sodium hypochlorite with hydrochloric acid and potassium bromide

I am currently taking a general chemistry course and during a lab they had us do the following procedure: Place $\pu{2 mL}$ of $5\%$ $ \ce{NaClO} $ solution in a test tube. Add $10$ drops of ...
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1answer
166 views

In acidic solution, what does ClO₃⁻ reduce into?

In acidic solution, what does $\ce{ClO3-}$ reduce into and, most importantly, why? It's $$\ce{6e- +ClO_{3}^- +6H^+ -> Cl^- + 3 H_2O}.$$ Now, with the gift of foresight, why was the equation for ...
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Why is it hard to reduce titanium dioxide?

Titanium is expensive, although it is not rare and titanium dioxide is a ubiquitous component, it's part of such mundane articles as toothpaste, paper or plastics. The reason for that is that the ...
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What is the reaction between oxalic acid and potassium permanganate?

I've already searched online some information about this equation, but everywhere I read, there's also sulfuric acid, which we did not use in the laboratory. We only used potassium permanganate and ...
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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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What is an oxidizer?

When talking about gaseous fuel / oxidizer mixture what does one mean by oxidizer if there is no oxygen involved? Is it correct to think of oxidizer as the more electronegative specie, because it is ...
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Oxidation number of nitrogen in KCN

How can one determine the oxidation number of nitrogen in $\ce{KCN}$?
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Balancing and combining the half equations in redox

I can understand redox equations of the following form, I break these down into half equations and combine them. $$\ce{MnO4^- + C2O4^{2-} -> Mn^{2+} + CO2}$$ Where I have issue is with the ...
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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 ...
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546 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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How does 1,3-dichloro-1,3,5-triazinane-2,4,6-trione (dichloroisocyanuric acid) generate hypochlorous acid when dissolved in water?

Can someone draw the reaction that leads to the generation of HOCl when dichloroisocyanuric acid (structure shown below) is dissolved in water?
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Thiosulphate acidic decomposition

I just came across this reaction $\ce{Na2S2O3 + 2HCl -> 2NaCl + SO2 + S + H2O}$ I was wondering if it was possible to predict the products of this reaction if I didn't know it (or any inorganic ...
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1answer
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Is combustion considered a redox reaction?

When carbon combusts with oxygen, is this considered a redox reaction since the oxygen atoms gain electrons and the carbon atoms lose them?
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303 views

What undergoes reduction in a zinc-copper voltaic cell?

In a $\pu{Zn-Cu}$ voltaic cell, the electrolyte is sodium chloride solution. The question was: In this cell, which of the following undergoes reduction? My answer was copper, but why is the exact ...
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If a sugar is nonreducing, does that mean it doesn't ionize in water?

I'm thinking of sucrose, which I learned is nonreducing, what I take to mean it doesn't accept/take electrons from the surrounding solution. Does this also mean that it doesn't ionize and thus has a ...
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1answer
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Mechanism of oxidation by dichlorotriazenetrione

How does dichlorotriazenetrione supply chlorine to a swimming pool and how does it oxidize organic material?