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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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2k views

Can silver metal be used to electrochemically reduce copper?

I have a solution of copper(II) ions and several cations. I am trying to reduce the copper ions to copper metal with electricity. My Ideas was to use silver as the anode and a copper wire as the ...
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1answer
7k views

How does chromium(III) react to form chromium(VI) with hydrogen peroxide?

$$\ce{2Cr(OH)3 + 4NaOH + 3H2O2 -> 2Na2CrO4 + 8H2O}$$ How does this reaction occur? We suddenly get sodium chromate in the place of chromium hydroxide. I can't understand it. We mix two hydroxides ...
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Why the products of combustion of Cu2S are Cu2O and SO2?

$$\ce{Cu2S + 2 O2 -> 2 CuO + SO2}$$ Why are not these oxides $\ce{Cu2O}$, $\ce{SO}$ or $\ce{SO3}$? Is it connected to the stability of these molecules?
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Reverse single replacement reaction

Is it possible using electrochemistry or some other method to reverse a typical single replacement reaction to go in the opposite direction. For example, is it possible to take silver metal and ...
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400 views

What is the logic behind the ion electron method of balancing redox reactions?

The ion electron method is a.k.a the half reaction method. How are we just allowed to add electrons and protons and water molecules? Why does it work anyway?
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Does bleach turn a substance white or colorless?

From what I understand, bleach works to weaken the ability of a substance to absorb light. Thus this seems to be "whitening" i.e. reflecting all light. In contrast, colorlessness (according to ...
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200 views

Would Al ions still be reducd to Al metal if it was aqueous soltion?

To my knowledge, Aluminium is mostly mined in the form of Aluminium oxide or Al2O3 and then the Bayer process is used to extract and refine the pure Aluminium. Now, The Al2O3 must be in a molten ...
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Reaction of chlorine with hot/cold solution of hydroxide

When chlorine reacts with cold solution of say potasium hydroxide, the disproportionation goes to lower oxidation states: $\ce{Cl2 + 2 KOH -> KCl + KClO + H2O} $ Whilst with hot solution the ...
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659 views

Efficient oxidation of KCl to KClO3

I am trying to convert $\ce{KCl}$ to $\ce{KClO3}$ through an efficient process. I realize that I could electrolyze a solution of $\ce{KCl}$ to obtain some $\ce{KClO3}$ as a precipitate, however this ...
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59 views

Reduction of chlorate with phosphorus

Given $$\ce{10KClO3 + 3P4 -> + 3P4O10 + 10KCl}$$ If 52.9 grams of $\ce{10KClO3}$ reacts with excess $\ce{P4}$, what mass of $\ce{3P4O10}$ could be produced? How many moles of $\ce{KCl}$ could be ...
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Weird Wikipedia Section on Oxidizing Behavior of Nitric and Sulfuric Acids

It has been my understanding that when nitric, perchloric, or sulfuric acids act as oxidizing agents, they must exist as whole $\ce{HNO_3}$ or $\ce{HClO_4}$ or $\ce{H_2SO_4}$ molecules that are still ...
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How does a copper piece added in nitric acid change after nitrogen dioxide starts appearing?

There's an experiment I have no way of performing but want to know its results. The instructions (in short) are: Dip a piece of copper in a glass of concentrated nitric acid, $\ce{HNO3}$, using a ...
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1answer
1k views

Half cell reactions for oxidation of water by acidified solution of potassium dichromate

From Chemguide: I don't understand the first equation. The chromium atoms in the dichromate ion receive 6 electrons, and their oxidation state declines from 6+ to 3+. But where do the 14 hydrogen ...
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891 views

Removing aluminum "corrosion?"

I have some aluminum alloy, possibly 6063 or 7050 (no clue really) which has corroded. The finish might be silver-anodized but I doubt it due to the high polish, could be urethane. The item is a ...
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Why is chloride oxidised instead of water in copper chloride electrolysis?

For the Electrolysis of Copper Chloride: Cathode: $\ce{Cu^{2+} + 2e- <=> Cu}$ Anode: $\ce{2Cl <=> Cl2 + 2e- }$ I am confused about the reaction taking place at the anode. Wouldn't $\ce{...
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Can oxidation of ethanol by copper(II) oxide yield copper(I) oxide as one of the products?

We know that ethanol is oxidised by copper(II) oxide to an aldehyde. Copper is reduced from $\ce{Cu^2+}$ to $\ce{Cu}$. Can this reaction, with some specific condition, yield $\ce{Cu2O}$ instead? That ...
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1answer
965 views

Isn't the reaction of chloral with sodium hydroxide a disproportionation reaction?

Chloral undergoes a haloform reaction with sodium hydroxide. Now the carbon atoms in chloral are in the $\mathrm{+III}$ and $\mathrm{+I}$ oxidation state. Chloroform’s carbon is in the $\mathrm{+II}$ ...
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Is there a way to Determine if an Element can undergo Disproportionation?

Can we determine the lowest and highest possible oxidation numbers of an element? Since if we know this, then it is easy to determine whether the element will undergo disproportionation.
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Will oxidation/reduction of copper still occur in an electrochemical cell if it is not in an aqueous environment?

Notation of the reduction and oxidation of copper typically includes the aqueous state. Illustrated below: $$\ce{Cu(s) -> Cu^2+(aq) + 2e-}$$ This event usually occurs at 0.34 V. What if the copper ...
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1answer
61 views

Which species gives electron in the following reaction?

In a given reaction like this: $$\ce{FeO4^2- + 3e^- + 8H+ <=> Fe^3+ + 4H2O}$$ From where does the electron come in the acidic medium, as there is no other species to get oxidised in the ...
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1answer
554 views

Stereoselectivity differences in Lindlar's catalyst and Na/NH3?

Why does using the Lindlar's catalyst form cis-alkenes whereas $\ce{Na/NH3}$ forms trans-alkenes?
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554 views

Mechanism of dehydrogenation with nosylate

What is the mechanism of the attached reaction? How could nosylate do the dehydrogenate the species? The reaction is from this synthesis (46th IChO preparatory problem 26):
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1answer
285 views

How to balance a redox equation in molecular form?

I've spent a while trying to balance this equation in molecular form with no success. $$\ce{Cu + HNO3 -> Cu(NO3)2 + 2NO + H2O}$$ I need to find the coefficient of HNO3, which is 8. However, this ...
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1answer
212 views

Which procedure(s) will allow a student to differentiate between solid sodium sulfate and solid sodium sulfite?

I. Make solutions of each and look for a precipitate when added to 0.10 M Ba(NO3)2. II. Add crystals of each to 0.10 M HCl and watch for bubbles. III. Make solutions of each and test with a pH ...
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1answer
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How would I calculate the Normality of a 0.00167 molar solution of KIO₃?

I need a 0.01 N solution of $\ce{KIO3}$ to use as a standard in a Winkler titration. The protocol that I am using specifies that this is 0.3567 g L-1, which I have calculated to be 0.00167 M based on ...
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Mechanism of the oxidation of alcohols with KMnO4

Many oxidising agents, like chromate, dichromate, iodine in $\ce{NaOH}$ etc. seem to work via ester formation and elimination. For example, chromic acid will react with the $\ce{-OH}$ of alcohol to ...
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2answers
102 views

Is it possible to write a redox reaction with two oxidations and one reduction together?

Let's take the Redox reaction between ${MnO_4}^-, {C_2O_4}^{2-}$ and ${SO_3}^{2-} $ Is it possible to write the complete reaction as below or do I need to consider the two reactions separately? $\...
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1answer
264 views

Experimentally finding order of a reaction

For the reaction of bromocresol green and bleach, I was supposed to conduct an experiment to find the order of the reaction with respect to bleach. To do this, I used a fixed amount of bromocresol ...
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2answers
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Is a highly oxidized element more electropositive than a lesser oxidized counterpart?

My issue I have a significant problem with the following excerpt from a general chemistry text: Note that ON stands for oxidation number (state). The excerpt is with regard to polyatomic anions - ...
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1answer
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How to calculate the electrochemical potential of Iron(II/III) and saturated calomel electrode?

Set up an electrochemical cell where the cathode is the system in question B, $\ce{Fe^2+ -> Fe^3+}\ E = 0.68~\textrm{V}$, whereas the anode is a saturated calomel electrode ($0.244~\mathrm{V}$ ...
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597 views

Fe 2+ and MnO4- titration?

As a lab experiment, I am preparing a mixture of iron tablets dissolved in sulfuric acid so they can be titrated against $\ce{MnO4-}$. The tablet contain insoluble filler material. Why is it ...
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170 views

Adding reduction potentials?

Will it be wrong to add reduction potentials of two intermediate reactions to get reduction potential of net reaction(just like as we do in adding enthalpies and applying Hess's law)? What is the ...
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125 views

Will bases typically precipitate silver atoms from silver ions?

In class I learnt that one can dissolve many substances using acid and that this can be predicted using standard electrode potentials. For example, $$\begin{align} \ce{Zn &-> Zn^{2+} + 2e^-} ...
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1answer
48 views

How long will it take for a measurable change in mass (corrosion) in an iron copper corrosion cell to happen?

I am planning to do an experiment, in which I will test the affect of salt concentration on corrosion rate. Would there be a relationship? How long would it take for rust to form, that could be ...
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1answer
784 views

Trying to displace iron from ferrous sulphate heptahydrate using aluminium foil but nothing has happened

I started by dissolving the sulphate into water and filtering it as I noticed there was a dirty residue lying at the bottom. (I am using ferrous sulphate that is commonly used in gardening.) I then ...
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1answer
7k views

Why does bromine react with iron(II) but not iodine?

My question comes from the answer (C) to this question: Firstly, (correct me if I'm wrong please) I thought that the answer could either be C or D since the other answers are negative ions which can'...
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1answer
5k views

Stability of MnO4- in basic vs acidic conditions

Why is $\ce{MnO4-}$ more stable in basic than acidic conditions? I know that electrode potential values suggest this, but what is the underlying chemical explanation for the phenomenon?
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Uses of oxidizing and reducing flames

Why do we use oxidizing and reducing flame in different analytical tests? For example, in the charcoal block reduction test, we use reducing flame. Why? How does this affect the salt to be reduced ...
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1answer
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Counterintuitive Reaction of Aluminium On Steel Balls

There is a certain video which I just watched about 2 large cast iron balls. If the balls are struck together, no reaction happens, but if one is covered in aluminium foil and then struck, a large ...
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1answer
855 views

Single step transformation of a carboxylic acid into an aldehyde

What are the different ways of transforming a carboxylic acid into an aldehyde in a single step ? (as opposed as for instance first transforming it to an ester then to an aldehyde) The bottom of this ...
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1answer
2k views

Conversion of carboxylic acid to alcohol

Is it feasible to convert carboxylic acids to alcohols? I know the reverse is done during the oxidation of alcohols (e.g. in the production of vinegar), but is it possible to do it the other way round?...
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91 views

What are the chemical formulae for galvanic corrosion of iron (rusting)?

The conditions for corrosion, I am searching equations are as follows: The other metal is copper The temperature is $25~\mathrm{^\circ C}$ The electrolyte is $\ce{NaCl}$ pH 7 A limited amount of ...
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1answer
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Current in a galvanic cell

I was looking through chemistry textbooks to find out how to determine how much current a galvanic cell should generate and what affects that current value. However, I did not find anything: textbooks ...
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Why oxygen is enclosed in parenthesis in some chemical reaction?

While going through my chemistry text book I came through the following reaction. $\ce{RCH2OH + (O) -> RCHO + H2O}$ In the above reaction why oxygen atom is enclosed in parenthesis ?
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254 views

Comparing Methods of Determination of Dissolved Oxygen Content in Water Sample

I am currently doing an IB Chemistry Individual Investigation on dissolved oxygen in water samples by using Winkler method. However, my teacher suggested that I have to use oxygen probe as a standard ...
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252 views

Galvanic cell chemistry

I made a galvanic cell with the anode electrode being aluminum and the electrolyte being aluminum sulfate. The salt bride was magnesium chloride. I am a little confused on what my oxidation equation ...
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1answer
1k views

how to identify reaction medium by looking at the equation ( for h2o2)?

$\ce{Ag2O + H2O2 -> 2Ag + H2O + O2}$ My book says the medium is alkaline as $\ce{H2O2}$ gives $\ce{O2}$ on reduction only in alkaline medium only but $\ce{O2}$ is produced in acidic medium too. Is ...
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3k views

If losing electrons means getting oxidized, then does it mean that ALL metals are reducing agents, since they themselves get oxidized?

I was just going through my last year's school textbooks and while I was reading this chapter on Redox, this above question crossed my mind. Shouldn't it be true that since ALL metals lose electrons ...
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1answer
559 views

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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122 views

What factors influence the resultant oxidation state of Fe in 3Ca(OH)2+2FeCL3?

$\ce{3Ca(OH)2 + 2FeCl3 -> 2Fe(OH)3 + 3CaCl2}$ What factors influence the resulting oxidation state in the iron hydroxide molecule in this reaction? Since iron's oxidation state ranges from +2 to +...

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