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
795 views

How exactly does a battery work (specifically Pb/H2SO4/H2SO4/PbO2 lead acid battery)?

Specifically talking about the lead-acid battery, I understand (or think I understand) this much: The anode, in the presence of the electrolyte, $\ce{H2SO4}$ will be oxidised: $$\ce{Pb (s) + SO4^2- (...
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1answer
11k views

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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1answer
38 views

Balancing the chemical equation using Oxidation Number Method [closed]

Permanganate ion reacts with bromide ion in basic medium to give manganese dioxide and bromate ion. Write the balanced ionic equation for the reaction. Please balance the equation using the oxidation ...
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1answer
124 views

Why must the total increase in oxidation numbers equal the total decrease of them in redox reactions? [closed]

In my book, under the topic of redox reactions, it is given, In all redox reactions, the total increase in oxidation number must be equal to the total decrease in oxidation number. Is this a ...
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2answers
297 views

Reduction of hydrogen sulfide by silver

Why can $\ce{H2S}$ be reduced by $\ce{Ag}$ when left in air: $$\ce{2 Ag + H2S -> Ag2S + H2}$$ If silver is a noble metal that should not reduce hydrogen?
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1answer
29 views

What is the equation for solving the concentration of the unknown from a Single-point Standard Addition Calibration for Potentiometry?

I know how to use the standard addition equation for a single-point analysis from an equation I got from the Analytical Chemistry book "Quantitative Chemical Analysis" 9ed by D. Harris. However, ...
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1answer
322 views

Why is the conjugate of a strong oxidizing agent a weak reducing agent?

I am a grade 12 student. While I was reviewing some electrochemistry, I had the following question. Take this reduction half-reaction: $$\ce{F2 (g) + 2e- <=> 2F- (aq) + $\pu{2.87V}$}$$ I know ...
3
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1answer
206 views

How to convert micromolar concentrations into molar quantities, when the volume is also known

\begin{array}{c|cccccc} \text{Sample} & \text{Ammonia} & \text{Phosphate} & \text{Silicate} &\text{Nitrate + nitrite} & \text{Nitrite} & \text{Mn} \\ & (\pu{\mu M}) & (...
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1answer
209 views

Multiple solutions in the balancing of redox reactions

While looking at the reaction between potassium permanganate and hydrogen peroxide in the presence of sulfuric acid a friend and I were attempting to find a general equation to yield the coefficients ...
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1answer
51 views

Cup with vinegar/salt/copper solution previously in it ran through dishwasher

Someone enjoys making jewelry, and saw an online tutorial saying that you can mix equal parts of vinegar and salt, and leave copper in it for a while to oxidize it, and turn it green. After doing ...
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0answers
26 views

How to find out the value of 'n' in the equation (ΔG = −nFE)? [duplicate]

I can figure out the value of 'n' in simple equations like Fe³⁺ + e⁻ → Fe²⁺ (which would be n=1 here.) But in equations like 2Cu⁺→ Cu²⁺ + Cu, I can't figure it out. I assumed the value of n would be ...
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25 views

Why does half-reaction with largest positive potential will run as written while other is reversed?

While balancing the half redox reaction, the textbook indicated that the flip of equation is dependent on the size potential. But I do not understand the reason why it is like that. Please explain for ...
3
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0answers
66 views

The phlogiston theory [closed]

I have looked this theory up on google and found that the theory is that when metal is burnt calx (metal oxide) and phlogiston is created (metal --> calx + phlogiston). Then I found out that ...
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1answer
67 views

Oxidation of Vitamin C

How is ascorbic acid oxidized into dehydroascorbic acid? What is the reduction reaction in this case? Where are the 2 hydrogen atoms going?
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1answer
52 views

Why can solid lubricants operate only at lower temperature in oxidizing environment but higher temperature in reducing environment?

The two main dry lubricants are graphite and molybdenum disulfide. They offer lubrication at temperatures higher than liquid and oil-based lubricants operate. Dry lubricants are often used in ...
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2answers
2k views

Rearrangements of α-aminoketones in Clemmensen reduction

What is the possible mechanism for this reaction? Activated zinc in presence of concentrated hydrochloric acid is used for Clemmensen reduction, that is conversion of ketone group to methylene group. ...
2
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2answers
16k views

Oxidation number of nitrogen in KCN

How can one determine the oxidation number of nitrogen in $\ce{KCN}$?
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0answers
21 views

How to prevent creation of piranha solution when conducting hydrogen peroxide titration?

I'm testing the activity of horseradish peroxidase (HRP) under different conditions by measuring the change in concentration of hydrogen peroxide substrate after a given amount of time. To stop the ...
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1answer
74 views

What would be the concentration of products in this calcium producing system?

I wanted to figure out a way to make calcium metal with potassium oxide. $\ce{K2O}$ undergoes disproportionation at $\pu{350-430 °C}:$ $$\ce{2 K2O -> K2O2 + 2 K}$$ Now, if I mixed in $\ce{CaO}$ (...
2
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3answers
197 views

Redox reactions redefined

I saw in my textbook (NCERT class 11 part2 chemistry) that oxidation is defined as gain of oxygen or more electronegative element by a substance. After it was redefined and said as oxidation ...
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2answers
2k views

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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2answers
137 views

Why is hypochlorite a stronger oxidizing agent than other oxychlorides?

The reduction potentials of perchlorate, chlorate, chlorous acid and chlorine dioxide in acidic and basic solutions are listed in the table below: $$ \begin{array}{lcc} \hline \text{Oxychloride} & ...
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2answers
101 views

What happens when two galvanic cells are placed in series

I understand how a single galvanic cell works, and the relation of equilibrium and the Nernst equation. But this appears to contradict the higher voltage in a series configuration because it ...
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1answer
108 views

Making oxygen from iron oxide (aka rust) with sodium chloride?

I like videogames, and I've been playing a lot of "Oxygen Not Included" recently. It's not a perfect physics simulation, but it does appear to be realistic-ish (both Specific Heat and Thermal ...
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28 views

Where does the protons and electrons go in this redox reaction?

In the above oxidation reaction, does the 2 protons and electrons released get accepted by oxygen molecules? If not, where do they go? Appreciate all answers :)
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2answers
362 views

Reduction and oxidation in organic chemistry

What is the meaning of reduction and oxidation in organic chemistry? In general chemistry I learned an OIL RIG mnemonic, i.e. oxidation is loss and reduction is gain (of electrons). But what do we ...
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3answers
4k views

Difference between Lindlar and Rosenmund catalysts

Is there any difference between the Lindlar and Rosenmund catalysts? I've checked around, and it seems the same compounds are used to make both. Is there a difference in their reactivities or are they ...
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2answers
68 views

Reduction of ester in presence of ketone group

As there is no ring expansion I'm assuming that a carbocation should not form at ester carbon as it leads to ring expansion. But is there any an exception to it? Also the hint provided along with this ...
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1answer
139 views

Burning magnesium ribbon [closed]

I know that this might sound wrong but, in the reaction $$\ce{2 Mg(s) + O2(g) → 2 MgO(s) + energy}$$ isn't oxygen supposed to be oxidised as it has excess electrons $(\ce{O^2-})$ and can donate a ...
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2answers
4k views

What is purpose of sulfuric acid in iodine extraction?

I am trying to extract iodine from kelp following this guide here. It calls for sulfuric acid, but I don't see what this does do help the reaction. I thought the reaction was simply oxidizing iodide ...
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1answer
58 views

How to oxidize tantalum? [closed]

I am interested in learning how to oxidize tantalum. I have seen some tantalum rings that the sellers say is a permanent smokey blackish color. But I've spoken to some people that say tantalum cannot ...
6
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1answer
33k views

What determines the strength of reducing and oxidizing agents?

The best reducing agents are located at the bottom left of the periodic table (low electronegativity) and the best oxidizing agents are located at the top right of the periodic table (high ...
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1answer
33 views

Fuel cell potential for the electrolysis of ammonia

I am trying to calculate the fuel cell potential for the electrolysis of ammonia with the following equation: ...
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1answer
74 views

Can antimony pentafluoride be made by adding hydrogen fluoride to antimony trifluoride?

I was looking at how the strongest acid was made and I found something I did not understand. On the Wikipedia page for antimony trifluoride it shows the production of $\ce{SbF3}$ using $\ce{HF}$: $$\...
6
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2answers
122 views

How do metals split the oxygen double bond during corrosion?

For a metal like $\ce{Mg}$ to corrode into $\ce{MgO}$, the double bond in $\ce{O2}$ must break. Since the dissociation energy of $\ce{O2}$ is 500 kJ/mol, using estimates from the Boltzmann ...
5
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2answers
5k views

Equivalent weight in case of disproportionation reaction

We all know that $\text{Equivalent weight} = \frac{\text{Molecular weight}}{\text{n-factor}}$ However consider a reaction like: $\ce{Br2 + OH- -> Br- + BrO3- + H2O}$ where oxidation numbers of $\...
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0answers
30 views

Reaction between copper and silver(I) nitrate in aqueous medium

What is the reaction between $\ce{Cu}$ and $\ce{AgNO3}$ taking place in aqueous medium? The answer given was: "Only" oxidation of $\ce{Cu}.$ My concern is: how is only oxidation of $\ce{Cu}$ ...
8
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2answers
4k views

Can lead(II) oxidize tin metal in aqueous solution?

According to my textbook, element $\ce{X}$ can oxidize element $\ce{Y}$ if $\ce{X}$ was lower in the activity series. Lead is lower than Tin in the activity series table in the textbook, but the ...
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2answers
48 views

Is this balanced redox equation correct? [closed]

I'm trying to balance an equation using oxidation numbers $\ce{MnO4^- + H+ + Cl- -> Mn^2+ + Cl2 + H2O}$ my suggestion: $\ce{MnO4- + 8H+ + 5Cl- → Mn^2+ + 2.5Cl2 + 4H2O}$ the 2.5 $\ce{Cl2}$ is ...
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1answer
281 views

Reason of dissociation of water molecule in electrolysis

$\ce{H2O}$ molecule is dissociated into $\ce{OH-}$ and $\ce{H+}$ ions on reduction at the cathode in electrolysis. But what happens at the atomic level to $\ce{H2O}$ that proton and hydroxide ions get ...
0
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1answer
66 views

Why does hydrogen burn spontaneously in fuel cell at room temperature?

It's well known that if you mix $\ce{H2}$ and $\ce{O2}$ in ambient conditions, the $\ce{H2}$ will be stable indefinitely, and will only react with $\ce{O2}$ to form water when ignited by a flame. The ...
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1answer
46 views

Redox titration or iron(II)

The concentration of $\ce{Fe^2+(aq)}$ can be determined by a redox titration using A. $\ce{KBr}$ B. $\ce{SnCl2}$ C. $\ce{KMnO4}$ (basic) D. $\ce{KBrO3}$ (acidic) Can anyone please ...
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1answer
126 views

Reaction of potassium with water

In general, when we put potassium into water, it will produce potassium hydroxide and hydrogen: $\ce{2K + 2H2O ⟶2KOH + H2}$ However isn't the following reaction also possible? $\ce{2K + H2O ⟶K2O + ...
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2answers
3k views

How to write equations for a reaction of metals with water

Please write two equations for reacting lithium with water and barium with water. Make sure to add the states of matter after each compound. Currently, for lithium I have the equation $$\ce{2Li(s) +...
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3answers
46 views

Can Iron(III) oxide oxidize elemental iron in a nitrogen environment under room temperature without any catalysis? [closed]

Will there be electron transfer to allow this process to happen: $\ce{2 Fe(III) + Fe(0) -> 3 Fe(II)}$
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3answers
3k views

Reaction mechanism of combustion of hydrogen

After a discussion about the usefulness of hydrogen fuel for cars with a friend of mine, I wondered what the reaction mechanism for combustion of $\ce{H2}$ was. I only study (well almost) organic ...
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1answer
95 views

What are the half reactions for the redox reaction between SO2 and iodine?

What are the half reactions for the redox reaction between $\ce{SO2}$ and iodine? The relevant chemical equation: $$\ce{ SO2 + H2O + I2 -> H2SO4 + 2HI}$$ This is what I think it is, not sure if ...
4
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1answer
349 views

Reaction between copper(II) iodate and iodide

I was attempting the following question from IChO 1989, which involved balancing of redox equations. One may just expect this to be a typical iodate-iodide redox reaction, usually employed in ...
2
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2answers
244 views

Leaching of copper using zinc

Why can we not use zinc for extracting copper from a solution containing $\ce{Cu^2+}$ ions even though it is a better reducing agent than $\ce{Fe}$? I am studying metallurgy and I cannot understand ...
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0answers
26 views

Electric potential of a redox reaction (without solids)

I need someone to help me with a problem: We have a solution which is $\pu{0.1 M}$ of $\ce{KMnO4}$ and $\pu{0.1 M}$ $\ce{Fe^2+}$ and has $\mathrm{pH}=0$. Given the electrical reduction potential of ...