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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Energy released by aluminum reactions

I heard that aluminum reacts violently when exposed to hydrochloric acid. I was wondering how much energy is released by this reaction. Preferably in MJ/kg or MJ/l. Assuming the reaction needs 2 moles ...
Nitrogen-8's user avatar
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Oxidation of sulfide

A textbook states that KMnO4 in acidic medium can oxidise H2S only to S but PbS is oxidised all the way to sulfate. Why do we get different products simply by changing the cation, and is there a way ...
Samj's user avatar
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Hydrogen oxidation number

I am aware that since 2005, IUPAC guidelines established that hydrogen is more electronegative than all elements from group V in the periodic table (you can check official documentation). Thus, $\ce{...
SerMig1111's user avatar
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3 answers
101 views

Why are we permitted to add things to balance redox equations?

Consider balancing redox half equations. As a general rule, we can add electrons, water, hydrogen ions or hydroxide ions to balance the redox half equation. However, it is not entirely clear why we ...
11221's user avatar
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The importance of nature of medium while reduction of permanganate

I was just going through some reactions related to $\ce{KMnO4}$ when I came across this. In acidic medium, $\ce{MnO4- +5e- + 8H+ -> Mn^2+ +4H2O}$ Here, the $\text{n-factor}$ is 5. In neutral (...
DarkKnight's user avatar
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3 answers
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Inconsistency in balancing of the equation for lead sulfide oxidation by ozone [duplicate]

The following question was asked in JEE Examination : $\pu{1 mol}$ of $\ce{PbS}$ is oxidized by $X\ \pu{mol}$ of $\ce{O3}$ to get $Y\ \pu{mol}$ of $\ce{O2}$ : The answer to which is given as 8. If I ...
orionbuff_62's user avatar
2 votes
2 answers
109 views

Does the electric field of a battery exist before a wire is connected outside?

Imagine a galavanic cell. What I am wondering is, what causes the inital oxidation of the less nobel metal to occur initally. Is the electric field there before you connect a wire, which would allow ...
Niclas's user avatar
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Redox half-reactions involving gold at three distinct oxidation states

I am preparing for my exam, and for some reason really struggle with half-reactions in the context of Galvanic cells. I do manage to solve the more straight forward questions, but really struggle with ...
Idan Ofek's user avatar
1 vote
3 answers
85 views

How to deduct the concentration of chloride in a silver/silver chloride electrode, given the cell notation

I have this cell notation: $$ \ce{Zn|ZnCl_2(0.05M)||AgCl(s)|Ag} \tag{1} $$ What is the physical shape of this cell? I know $\ce{AgCl}$ has very low solubility, and the problem has no concentration on ...
Martín Montoto Fernández's user avatar
6 votes
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How to explain oxidizing power from Molecular Orbital Theory

I am trying to explain the oxidizing property of $\ce{Fe^3+}$ in $\ce{H2O}$ and $\ce{CN^-}$ which is $\ce{[Fe(H2O)6]^3+}$ and $\ce{[Fe(CN)6]^3-}$. The electrochemical reactions along with their ...
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Aqueous electrons in electrochemical cells [closed]

In the context of a zinc-copper electrochemical cell, zinc atoms at the anode are oxidized, releasing electrons and forming zinc ions that dissolve into the solution ($\ce{Zn(s) -> Zn^{2+}(aq) + 2e-...
Kris's user avatar
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Non-catalysed exhaust gas

I'm writing up an academic paper (medical) on in-car exhaust levels and their effect on health. So as to ensure detection of leak-points that are located further along than the catalytic converter, in ...
Medical_researcher's user avatar
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Copper reaction with nitric acid

According to this paper, the green colour from the reaction of copper and nitric acid could be explained: The color is greenish, probably as a result of a combination of the pale-blue color of the ...
Seiji's user avatar
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Neglected partial pressures dependence of water splitting

I am studying electrochemical water splitting and I have a huge doubt. The standard redox potential for the total reaction is 1.23 V, but this is in standard conditions, where the hydrogen and oxygen ...
th3f4tk1ng's user avatar
2 votes
2 answers
251 views

Oxidation of compounds vs elements

I was under the impression that when talking about oxidation/reduction, we are referring to specific elements, and the changes in their oxidation numbers. However, I saw the following reaction ...
firstnamelastname45341's user avatar
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2 answers
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Is it possible to make thermite that detonates? [closed]

Why does thermite burn pretty slowly? Can it burn much faster if the components were ground to much smaller grain sizes? Can it be made to actually detonate--that is, the entire pile turning into ...
John Smith's user avatar
1 vote
2 answers
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Oxidation of Isopropanol by Permanganate in Basic Solution

so I've been designing an experiment where I will explore the effect of isopropanol concentration on the colour change of a solution containing permanganate, isopropanol, and NaOH. I know that the ...
Brian Yu's user avatar
2 votes
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How can I refine my method of determining iron content in spinach?

I have begun a chemistry experiment that attempts to determine how iron content in spinach is affected by the length of time it is cooked. Through research, I learned that iron content is often ...
beebs's user avatar
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How does electric current flow in daniell cell?

The actual question in my mind is that ……..at anode zinc oxidises to form $\ce{Zn^{2+}}$ and $2$ electrons, but it should be the same case at cathode because copper should also oxidise to form $\ce{Cu^...
Physics student's user avatar
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2 answers
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Help in balancing redox reaction

I've started balancing redox reactions, and one particular reaction has tripped me up. $$\ce{PbS + O3 -> PbSO4 + O2}$$ $\Delta ON$ for $S =8$ $\Delta ON$ for $O =-2$ Here, $O_2$ acts as a spectator ...
Mr Gubbo's user avatar
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Disproportionation reactions

Are there any examples of a disproportionation reaction being harnessed to do useful electrical work? It is of course possible in a comproportionation reactions, such as a lead-acid cell.
Bill Harrison's user avatar
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2 answers
107 views

How do electrons travel through a fuel cell or flow battery with multiple cells?

I understand that if you have a fuel cell or flow battery with a single cell that electrons will go from the electrode and through an external circuit across the load which the fuel cell / flow ...
DavePiae867's user avatar
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1 answer
56 views

Redox Reaction Half Equations

$$\ce{PbS(s) + 4 H2O2(aq) -> PbSO4(s) + 4 H2O(l)}$$ I been trying to find the half equations for a while now. How would you find the balanced half equations for this redox reaction? Do you just add ...
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Using biochemical standard state versus chemical standard state

Can I use the table below to calculate the standard cell potential, $E^{\circ}$, of ethanol oxidation to acetaldehyde (EtOH + 1/2O2 $\rightarrow$ Acetaldehyde + H2O)? Does it matter that the half-...
GMoss's user avatar
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Potassium permanganate and hydrogen peroxide decomposition

I saw a reaction by chemicalforce on YouTube where he decomposed $\ce{H2O2}$ into $\ce{H2O}$ and $\ce{O2}$ using potassium permanganate. The permanganate is a catalyst in the reaction. I am wondering ...
ChemEng's user avatar
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1 answer
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How would you balance this equation by half reaction [closed]

$\ce{Na + Hg2Cl2 —> NaCl + Hg}$ I was told to balance this reaction by using the half reaction method. I am confused to as how you would do that since the $\ce{Cl}$ is with both the $\ce{Na}$ and ...
Friendly Carrot's user avatar
3 votes
1 answer
150 views

How and when do redox indicators work?

In redox titrations, for example cerimetry, cerium(IV) is reduced to cerium(III) with a reducing analyte. The Ce(IV)/Ce(III) redox potential is around $\pu{1.76 V}$. We keep track of the solutions' ...
Mäßige's user avatar
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6 votes
3 answers
551 views

What part of ascorbic acid is oxidized when it reacts with iodine?

When vitamin C reacts with iodine, it will lose two of its electrons (oxidation) which iodine will accept (reduction). What I do not understand is what part of the vitamin C exactly is losing the ...
user138990's user avatar
-5 votes
1 answer
86 views

Is the n factor/ valency factor of H3PO4, 2 or 3? [closed]

I'm very confused with search results I see on Google and different websites. I think the n-factor of H3PO4 is 3 because three H atoms are already bonded to three oxygen atoms. But some sources say it ...
NNS's user avatar
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4 votes
1 answer
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Does reduction occur well above the reduction potential?

I was reading the voltammetry section of Analytical Chemistry 2.1 (Harvey), and it says that for the reduction of $\ce{[Fe(CN)^{III}6]^3-}$ to $\ce{[Fe^{II}(CN)6]^4-}$, which has a standard reduction ...
mertvy's user avatar
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-1 votes
1 answer
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Effects on pressure on reverse electrolysis

I am interested in the effects on pressure of the following reaction. $$\ce{O2 + 4H+ + 4e- → 2H2O}$$ I have been trying to find data on this for a while, and I am sure that the information exists, but ...
Evelyn21's user avatar
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1 answer
163 views

Is it not possible to balance the equation $\ce{I2 +O3 -> I4O9 +O2}$ in many ways? [closed]

The above reaction can be balanced in many ways. For example, the coefficient of $\ce{I2}$ is two when coefficient of $\ce{I4O9}$ is one. But the coefficient of $\ce{O3}$ and $\ce{O2}$ can be 5 and 3 ...
Rassank's user avatar
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2 answers
41 views

Will H+ ions undergo reduction at cathodes in a chemical cell? [closed]

Metal P is the cathode, and it should attract anions. In this cell, anions present are Cl- and OH-, but they are reducing agents, reduction should occur at cathodes. So will H+ ions undergo ...
gatiskandis's user avatar
2 votes
2 answers
194 views

Does ferrocenium chloride ([Fe(C5H5)2]Cl) exist as a stable compound?

I am interested in using ferrocenium chloride ($\ce{[Fe(C5H5)2]Cl}$) for a synthesis application, but I couldn't find any sources referring to its existence, even though some websites and a figure in ...
psansoldo's user avatar
3 votes
1 answer
150 views

Role of MnSO4 in permanganometric titration

This might sound like a stupid question, but I have been unable to wrap my head around it. Recently in a lab I had to titrate H2C2O4 with KMnO4 in acidic medium (H2SO4). However, in the work, it ...
confusionfromarizona's user avatar
1 vote
2 answers
55 views

What is brown/red precipitate in battery acid

I am working on recovering some lead acid batteries that have lost some of their capacity. I drained all of the sulfuric acid out and there was an awful lot of brownish red precipitate in it. My ...
Alan's user avatar
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2 answers
109 views

Why does the reaction "pause" when the battery is not connected to a circuit? (or does it?)

The general set up, In an alkaline battery, the negative electrode is zinc (Zn) and the positive electrode is manganese dioxide ($\ce{MnO2}$). The alkaline electrolyte of potassium hydroxide (KOH) At ...
Reuben's user avatar
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1 answer
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How do I explain that voltage decreases when increasing the concentration of the cathode in a voltaic cell?

I just finished a lab experiment in which I built a voltaic cell with copper (II) sulphate and zinc sulphate. My experiment was to identify the correlation between the concentration of copper (II) ...
Night's user avatar
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0 votes
2 answers
172 views

What is meant by 'as Cl2'

I feel like I'm over thinking this one, but think I need a confirmation (and quantified example) to put my confusion to bed. I'm more a mechanical than chemical background but trying my best. I really ...
Kuhrta's user avatar
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When forming an epoxide with m-CPBA, what happens when we wash our mixture with Na2S2O4?

The m-CPBA is reduced by the $\ce{S2O4^{2-}}$, but why does it leave the mixture then? Why does the reduced m-CPBA leave with the oxidised $\ce{S2O4^{2-}}$?
Dlouna.J's user avatar
-2 votes
1 answer
93 views

is alkyl halide turning into alkene reduction or oxidation? [closed]

Is the reaction of 2-iodobutane turning into but-2-ene reduction or oxidation reaction?
blob of water's user avatar
4 votes
2 answers
177 views

Acid dissociation constant from conductometric data

$\ce{0.007 M}$ aq. solution of anilinium hydrochloride had molar conductivity equal to $\pu{119.4 S cm2 mol-1}$, which became $\pu{103 S cm2 mol-1}$ when a few drops of aniline were added to the ...
Harikrishnan M's user avatar
2 votes
1 answer
156 views

Find cell configuration notation for permanganate in acidic medium

They gave us an unbalanced reaction of permanganate and iodide in acidic medium, and ask to balance the reaction using redox methods and the write the cell configuration notation for the resultant ...
creepshow's user avatar
-3 votes
1 answer
105 views

Which of the following might turn NaNO2 into N2? [closed]

Which of the following might turn $\ce{NaNO2}$ into $\ce{N2}$? A. $\ce{NaCl}$ B. $\ce{NH4Cl}$ C. $\ce{HNO3}$ D. $\ce{H2SO4}$ The answer is B and we have $$\ce{NH4Cl + NaNO2 = NaCl + 2H2O + N2↑}.\tag1$...
youthdoo's user avatar
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1 answer
104 views

What causes ionisation in redox reactions?

I'm trying to understand what's behind the ionisation of atoms in a redox reaction. I apologise if the answer to this question is obvious. I've searched around, but, surprisingly, I haven't found a ...
John O'brien's user avatar
-4 votes
1 answer
219 views

What is the difference between combination reaction and addition reaction [closed]

In my textbook,two definitions were given separately Combination: Two or more substances react to form one product. Addition: Something is added to a chemical substance without elemination. What is ...
Kick's user avatar
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3 votes
1 answer
88 views

Reduction of di-N-substituted imidazole to imidazoline to remove counterion?

I would like to synthesize a di-N-substituted imidazole (compound 4) in its free base form or reduce it to generate an imidazoline (compound 5) to remove the bromide counterion to the imidazole ring. ...
toodles's user avatar
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-1 votes
2 answers
569 views

Why iron reacts with steam to give Fe3O4 not Fe2O3? [duplicate]

Why $\ce{Fe}$ with $\ce{H2O}$ gives $\ce{Fe3O4}$ not $\ce{Fe2O3}$? Like, $\ce{Zn + H2O \rightarrow ZnO + H2}$, why $\ce{Fe}$ doesn't simply gives $\ce{Fe2O3}$ when it reacts with steam?
O M's user avatar
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1 answer
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Where does the ionisation energy for a reaction to take place comes from? [closed]

Can anyone tell me exactly what happens during a chemical reaction in terms of ionisation energy? I know that during a reaction there is an exchange of electrons (except for those where electrons are ...
Zane Stockton's user avatar
-3 votes
1 answer
64 views

Why does metal atom get an effective potential difference in voltaic cells [closed]

Why is it that metal atoms , experience this potential difference when immersed only in their salt solutions. When they are in contact in real life we cannot see current conducting through it.
Naveen V's user avatar
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