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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Why do we use [H⁺] and [OH⁻] in balancing redox reactions instead of using [H₃O⁺] and [OH⁻]? [duplicate]

For what reason is it universally agreed upon that we use $$\ce{H+ + OH-}$$ ions in balancing water on either side of the reaction, but not the $$\ce{H3O+}$$ ions?
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Winkler's method in the absence of iodide

I'm currently doing an IB chemistry individual investigation on the effect of adding bleach to water on the water's dissolved oxygen content. I've used Winkler's method for this and I'm just wondering ...
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Help understanding Electrochemistry diagram

I was reading some literature when i came across the following figure and was wondering if someone could help explain it to me. I see on the vertical axis it is potential vs Li/Li+ and see that Oxides ...
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1answer
94 views

Conditions for the reduction of dichromate by manganese(II) to chromium(III) [closed]

The unbalanced redox reaction $$\ce{Mn^2+ + Cr2O7^2- -> Mn^3+ + Cr^3+}$$ occurs in what type of condition? (a) Acidic (b) Basic (c) Neutral (d) Indeterminable
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Question About Reversible Reactions and Batteries

So my book says that the batteries we have considered so far( Daniell cells) are low life span, because they reach equilibrium too fast. In the next paragraph, it says they are also made by ...
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226 views

Electric fields in a galvanic cell

I have read hat there is two types of electric fields exist in galvanic cell.I understand E because of charges accumulated on electrodes but what about other E -field? What does cause this field and ...
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1answer
264 views

How can batteries reach equilibrium if the reactions are irreversible?

My book says that the batteries we have considered so far (Daniell cells) have a low life span because they reach equilibrium too quickly. In the next paragraph, it states they are also made by ...
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193 views

How does different pH affect copper electroplating [closed]

I'm currently investigating the effect on the concentration of hydrogen ions in the copper sulfate solution on the amount of copper deposited on the cathode within a certain amount of time. I've ...
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1answer
45 views

In a galvanic cell,do charges accumulate on electrodes 1st (then redox occur) which produce E in the wire when we connect between electrodes? [closed]

We study that when we connect a wire between the terminals of a battery ,an electric field in established between terminals due to potential difference .Is the potential difference result of ...
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1answer
63 views

General Oxidant - Reductant Battery

In general, is it true that if I connect an aqueous oxidant to an aqueous reductant via a wire then a current flows along the wire? In particular, does current flow in the following scenario? Imagine ...
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1answer
143 views

Latimer diagram for a metal in basic solution

Write the four half cell reactions from the Latimer diagram for a metal $(\ce{M})$ in basic solution. $$\ce{\overset{+6}{M}O4^2-(aq) ->[\pu{0.25 V}] \overset{+5}{M}O4^3-(aq) ->[\pu{0.55 V}] \...
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Can concentrated sulfuric acid oxidize iron(II) to iron(III)?

Can concentrated (18 M) $\ce{H2SO4}$ oxidize $\ce{Fe^2+}$ to $\ce{Fe^3+}?$ Or does it actually block the oxidation? I read in some forum somewhere that in order to prevent $\ce{Fe^2+}$ from being ...
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Why is this reaction not a redox? [closed]

My question may seem too simple. But I couldn't find why this is not a redox. $$\ce{Hg2(NO3)2 + 2KBr -> Hg2Br2 + 2KNO3}$$ In $\ce{Hg2(NO3)2}$ compound atoms have following states: O: -2 N: -3 Hg:...
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990 views

Redox Titration in investigating change of Iron in Avocado [closed]

I'm trying to investigate the change in iron in an avocado as it ripens. I'm planning on using redox titration but still a bit unsure of how to carry out the investigation (method). Do you have any ...
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Reaction of aqueous sodium carbonate with aluminum foil

Aqueous sodium hydroxide is known to react with aluminum foil in an exothermic, hydrogen-gas releasing reaction like $$\ce{2NaOH(aq) + 2Al(s) + 2H2O(\ell) → 2NaAlO2(aq) + 3H2(g)}$$ However, on ...
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eV and redox potential

I am trying to estimate the redox potential of an excited state as described in this reference. The paper says: The reduction potentials associated with the excited states cannot be directly ...
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149 views

Can I reverse an iron redox reaction with potassium hydroxide and electricity?

For a school project, about clean energy, me and my team are trying to build an iron battery. We are using a piece of iron (anode), potassium hydroxide (electrolyte), carbon electrode (cathode) ...
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Oxidation of fructose with conc. HNO3

I recently studied carbohydrates. I was taught that fructose on oxidation with strong oxidizing agents like concentrated $\ce{HNO3}$ yields glycolic acid and tartaric acid along with trihydroxy ...
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1answer
241 views

Equivalent mass in case of disproportionation reaction

I came across a question where the equivalent mass of hypophosphorus acid is to be found in the given reaction: $$\ce{2H3\overset{+1}{P}O2 -> H3\overset{+5}{P}O4 + \overset{-3}{P}H3}$$ If $M$ is ...
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Reaction of getting jarosite from pyrite

I am doing a PhD about archaeometry in order to study the contaminations and alterations that occur to the ceramics which are buried in a marine environment. In my research, I have found pyrite in the ...
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2answers
260 views

How to know dichromate is being reduced from Cr⁶⁺ to Cr³⁺?

When potassium dichromate is being used as an oxidising agent, it gets reduced from chromium(VI) to chromium(III). Is there any way to know that or calculate that other than being familiar with ...
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55 views

Calculate the potential of each electrode, $\ce{Mn(OH)2}/\ce{Mn}$ ox/red couple

So the exercise goes like this: We consider the chemical battery(i have no idea what is its actual english name since i'm translating), $\ce{Mn_{(s)}/Mn(OH)_2//Cu^{2+}/Cu_{(s)}}$ Where $\ce{Mn}$ is ...
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147 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
525 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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190 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
129 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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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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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 ...
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108 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
142 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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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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85 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 $\ce{CaO}$ (...
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3answers
343 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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Br- and I- ions give layer test, but Cl- ion doesn't. Why? [closed]

One of the questions I found in an NCERT book. Interestingly I could not find the answer anywhere on the internet. Hence, stack exchange.
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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
444 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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2k 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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101 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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Is cyclic ether oxidised by periodic acid?

Is the three member ring of cyclic ether oxidised by periodic acid? As this also has oxygen attached to adjacent carbon so I think that cyclic ether of three members should be oxidised by periodic ...
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738 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
84 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 ...
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1answer
171 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
105 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 $\ce{HF}$: $$\...
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1answer
294 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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35 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 $\ce{Cu}$ ...
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2answers
51 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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279 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 ...
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1answer
111 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
107 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 help me on this ...
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2k 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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