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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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How to quantify the concentration of sodium nitrate leftover from eutrophication through titration?

In my experiment, I am trying to quantify the nitrate absorption by duckweed. I need a titration method to measure the left over nitrate levels in the solution. However, this is to be done in a school ...
-2 votes
1 answer
43 views

What is reduced in the reaction of magnesium with oxygen? [closed]

What is reduced in the reaction $$ 2\mathrm{Mg} + \mathrm{O}_2 \rightarrow 2\mathrm{MgO} $$ An oxygen molecule or an oxygen atom ?
3 votes
1 answer
328 views

It is possible to synthesize 3,3-diethylpentane ("tetraethylmethane") from carbon tetrachloride?

Compounds like tetraethyl silane or tetraethyltin can be made from their tetrachlorides using ethylating Grignards, but what about substituting carbon, would it work or steric hindrance would prevent ...
0 votes
1 answer
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Does a decomposition redox reaction with a single reactant and non-elemental products exist?

Does a decomposition redox reaction exist with a single reactant and non-elemental products and that this decomposition reaction cannot be decomposed in any condition to yield elemental products. For ...
1 vote
2 answers
111 views

Criterion for a good explosive

For a mixture to be good explosive, it's components should react violently. In other words it should release more energy in less time. Thus enthalpy change of the reaction should be very high and rate ...
2 votes
1 answer
3k views

Sodium metal in acetone

When I place a chunk of 99,99% pure sodium metal in a beaker of (100% chemically pure) acetone, the sodium metal starts reacting and dissolving into the acetone and it forms a yellow/brown liquid. ...
1 vote
1 answer
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Etching stainless steel

I need to etch some stainless steel for a project. I found some instructions that only require household chemicals (it's kind of hard to acquire chemicals here). It required 30% HCl and 3% H2O2. I ...
-3 votes
1 answer
66 views

Standardizing alkaline ferricyanide solution [closed]

The ferricyanide method of determining reducing sugars is simple but I need clarity on time of addition of potassium iodide solution. I am unable to observe change in color from yellow to blue. I even ...
0 votes
4 answers
103 views

How can reduction and oxidation occur separately in batteries if they're meant to be one reaction?

According to this page along with many others, oxidation and reduction must occur simultaneously. However, in a battery, it seems like they actually occur separately. Oxidation must first occur to ...
3 votes
1 answer
457 views

Why isn't NO considered combustible?

According to this (and a bunch of other sources), NO (nitric oxide) is not combustible. But that same source says NO rapidly reacts with O2 to produce NO2, which I thought was the definition of ...
1 vote
0 answers
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Indirect Titration of Sodium Bisulfite with Potassium Iodate

I'm trying to develop a procedure to determine the concentration (in g/ml) of a solution of sodium bisulfite (NaHSO3). I have already determined the solution concentration using a direct titration ...
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How to predict whether a redox or an acid-base reaction will occur? [duplicate]

I've been thinking a lot about this question, but even after intense research, I didn't find any satisfying answer, even here. So here's my question, illustrated with an example: We have a negatively ...
1 vote
0 answers
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Quenching reagents for specific reaction

A reaction general procedure is given as follows: A mixture of 2-fluoro-5-iodo pyridine $(\pu{1.0 mmol})$, methyl acetoacetate $(\pu{3.0 mmol})$, $\ce{CuI}$ $(\pu{10 mol\%})$, $\ce{K3PO4}$ $(\pu{3.0 ...
3 votes
2 answers
415 views

What gives dilute/conc nitric acid/ conc sulfuric acid their oxidizing property?

I know that dilute sulfuric acid and very dilute nitric acid don't have any oxidizing tendency while dilute/conc $\ce{HNO3}$ and conc $\ce{H2SO4}$ do. Why do these more concentrated acids have this ...
0 votes
1 answer
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Determining an unknown E° from two similar half ox/redox reactions

Use the oxidation half-cell and reduction half-cell, $\ce{Cr^3+/Cr^2+} = \pu{0.424 V}$ and $\ce{Cr^3+/Cr2O7^2-} = \pu{1.32 V}$, to determine the $E^\circ$ for $\ce{Cr2O7^2-/Cr^2+}$: a. $\pu{-1.75 V}$ ...
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Change in Gibbs energy for lithium redox reaction

I was reading an electrochemistry book by Thomas F. Fuller, in this book the thermodynamic values for the lithium redox reaction at standard conditions are the following: Reaction $\Delta G^o$ [kJ/...
4 votes
1 answer
228 views

How does a silver chloride electrode (Ag/AgCl) convert the potential in aqueous solution to the wire?

I am aware of the redox chemistry that happens at the electrode surface, but I'm not sure how exactly a change in electrical potential in the solution would change the potential in the electrode?
4 votes
0 answers
794 views

Why does the OAc group leave in the first step of Oxymercuration?

The above picture shows the first step of Oxymercuration. The electrons attack the Mercury atom but the OAc group leaves. Why is this? Hg is a transition metal with a number of available oxidation ...
4 votes
0 answers
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Does catechol give Tollens’ test?

Do hydroquinones like catechol or p-hydroxyphenol give Tollens’ test? I know that β-diketones can reduce Tollens’ reagent to give a “silver mirror”, so I would guess that due to tautomerization ...
1 vote
2 answers
2k views

Single electrode potential measurement

My textbook says that in a galvanic cell, it's not possible to measure single electrode potential independently. Instead, a Standard Hydrogen Electrode is used as the system is under equilibrium. Can ...
0 votes
0 answers
51 views

Equations for the Winkler method

I learned in my IB chemistry class that the chemical equations for the Winkler method are as follows. Step 1 2Mn2+(aq) + 4OH-(aq) + O2(aq) → 2MnO2(s) + 2H2O(l) Step 2 MnO2(s) + 2I-(aq) + 4H+(aq) → Mn2+...
-2 votes
1 answer
2k views

Oxidizing toluene to phenol [closed]

Can toluene be oxidised with air to produce phenol? What catalysts are needed?
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1 answer
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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 ...
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1 answer
119 views

What reaction takes place when ammonia and sulfur dioxide are introduced into barium chloride solution?

What reaction takes place when gaseous $\ce{NH3}$ and $\ce{SO2}$ are introduced into $\ce{BaCl2}$ solution and an insoluble white solid is produced? I think that the white solid could be $\ce{BaSO4}$ ...
5 votes
2 answers
362 views

Using potassium dichromate and sulfuric acid to clean test tubes after Tollens’ test

We had an experiment at school to find out the biomolecules contained in the different foodstuffs. After doing Tollens’ test which turned out to be positive, our teacher instructed us to clean the ...
-2 votes
1 answer
58 views

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{...
0 votes
3 answers
110 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 ...
11 votes
0 answers
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Why does the reaction of sodium nitrate, aluminium, and sodium hydroxide yield ammonia?

From Russian test problem 4301: $$\ce{3NaNO3 + 8Al + 5NaOH + 18H2O -> 8Na[Al(OH)4] + 3NH3(g)}$$ How does ammonia evolve here? Is it that we get hydrogen gas evolving in the reaction between Al and ...
6 votes
0 answers
15k views

How to determine the iron content in spinach from a titration with permanganate solution?

I used titration to find the mass of iron in a $5~\mathrm{g}$ sample of spinach after leaving the spinach to soak in tap water for five different lengths of times. I added $\ce{H2SO4}$ to the solution ...
2 votes
2 answers
130 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 ...
9 votes
2 answers
21k views

Does DIBAL-H reduce carboxylic acids?

Diisobutylaluminium hydride(DIBAL-H) reduces only carboxylic acid, ester or both? The answer given was that it only reduces ester. Is it correct that under any condition carboxylic acids are not ...
2 votes
1 answer
212 views

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 ...
1 vote
1 answer
2k views

Why does oxygen in OH- have an oxidation state of 2-?

I am watching videos on Khan Academy in order to go over redox reactions (a really weak area for me.) In Sal's video, "Oxidation state trends in periodic table" at 7:10, he says: If you had to ...
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1 answer
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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 ...
-2 votes
2 answers
91 views

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 ...
1 vote
1 answer
184 views

Redox titrations : Oxidation of metallic Iron by Potassium Dichromate

$\pu{0.31 g}$ of an alloy of $\ce{Fe + Cu}$ was dissolved in excess of diluted $\ce{H2SO4}$, and the solution was made up to $\pu{100 ml}$. $\pu{20 ml}$ of this solution required $\pu{3 ml}$ of $\frac{...
16 votes
5 answers
30k views

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 ...
-1 votes
3 answers
74 views

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 ...
11 votes
2 answers
300 views

Silver Tarnish and Reactivity Series

I read that silver in the presence of hydrogen sulfide corrodes to form silver sulfide and hydrogen. $$\ce{Ag + H2S -> Ag2S + H2}$$ But in the reactivity series silver is placed much below hydrogen....
5 votes
0 answers
446 views

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 ...
4 votes
2 answers
773 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 ...
-2 votes
3 answers
73 views

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 ...
2 votes
1 answer
160 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 ...
1 vote
3 answers
87 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 ...
-3 votes
1 answer
66 views

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-...
0 votes
1 answer
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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 ...
2 votes
0 answers
62 views

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 ...
2 votes
2 answers
259 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 ...
-3 votes
2 answers
98 views

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 ...
19 votes
1 answer
25k views

Does Br2/H2O oxidize all aldehydes including carbohydrates?

In many books, it is mentioned that aldehydes are easily oxidized even by mild oxidizing agents. However, I have never seen bromine water explicitly mentioned. But in the carbohydrates chapter, it is ...

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