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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61 views

Thermal reduction of other metal oxides beside Fe2O3

In the firing of ceramic glazes you can make an effect called oil spot. This is done by making two layers of glaze. A bottom layer rich in iron oxide (+15%) and a top white layer that's fairly ...
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105 views

How do the two half cells of Daniel cell know when they are connected?

I'm currently studying electrochemistry in school, and there is something I don't can't quite understand about Daniel cell. When you put $\ce{Zn}$ solid into $\ce{ZnSO4}$ solution, does the electrode ...
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55 views

Equation for Galvanization and Electrolysis of Saltwater with Copper and Zinc

I am looking for the chemical equations for both the galvanization and electrolysis of saltwater utilizing copper and zinc. The closest I have gotten was from this site: Explanation for the reactions ...
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123 views

Balancing redox equations with oxygens in multiple oxidation states

How do you balance this using the ion-electron method; $\ce{CrO5 + H2SO4 -> Cr2(SO4)3 + H2O + O2}$ The oxygen has multiple oxidation states in $\ce{CrO5}$, and none of the sites I looked this up ...
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154 views

Electrode potentials vs interfacial potential differences

Between an electrode and an electrolyte there exists an interfacial potential difference. Many authors give the electrode potential to be the electric potential of the electrode relative to the ...
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1answer
335 views

Does the order of a written redox couple matter?

My understanding is that a redox couple is an unordered pair of two conjugate species. So we could speak of the redox couple consisting of $Ag$ and $Ag^+$; depending on whether a given redox couple is ...
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86 views

Most understandable notation for reduction and oxidation potentials

Nowadays a lot of electrochemistry is done using just electrode potentials (i.e. reduction potentials), so if in doubt the notation $E^o$ tends to imply a reduction potential. However, some chemists ...
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1answer
314 views

Why do we write electrode potentials next to chemical reactions? [closed]

We might have a half cell consisting of the redox couple $\ce{Ag+}/\ce{Ag}$, which for example's sake might be fixed to be at the cathode (i.e. undergoing reduction). The reaction at the cathode is ...
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66 views

Log(Q) is zero, therefore the effect of temperature change is unaccounted for by Nernst Equation?

I have an internal assessment on Nernst Equation. The experiment is seeing how changing temperature effects cell potential. The solution are zinc and copper sulfate with each having concentration of ...
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742 views

Why ZnS can be seen as the solution is made alkaline? Explain with reactions [closed]

There is an extract in my book which i am not able to get. It says: Place strip of metallic zinc in aqueous solution of copper nitrate for about one hour. You may notice that the strip becomes coated ...
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398 views

Equations for the oxidation reactions of tea teaflavins and EGCG with potassium permanganate

For my chemistry investigation, I used Stamm's potassium permanganate method to investigate tea tannins with potassium permanganate to find the tannin content of teas. The method assumes complete ...
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108 views

Indicators of Cu(I) or Cu(II)

We performed an experiment in class where we placed a piece of copper wire in a solution of silver nitrate, we were tasked with predicted the mass of copper that should react and the mass of silver ...
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Nernst Equation for Lithium ion battery

For electrochemical cells we know $$ \Delta G = \Delta G^{\ominus} + RT\ln Q=- RT\ln Keq + RT\ln Q=-nFE $$ So for lithium ion batteries the reactions are Cathode $$ \ce{CoO2 + Li+ + e- <=> ...
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462 views

What is the oxidation state of Boron in Ammonia Borane? [closed]

So I was searching about the difference between redox reactions and Lewis Acid-Base reactions and came across classical example of latter, $$\ce{NH3 + BH3 \rightarrow NH3BH3}$$ Now in this example ...
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874 views

How to predict disproportionation products from Frost diagram?

I read that concave points in a Frost diagram disproportionate. But what are the products of the disproportionation? For example, in the Frost diagram for manganese at pH = 0, the species $\ce{HMnO4-}...
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1answer
498 views

Why is the voltage produced by a voltaic cell affected by temperature as described by the Nernst Equation?

I understand why changing the concentrations of the electrolytes in a voltaic cell affects the voltage. Given a zinc-copper cell for example, if I were to increase the concentration of the zinc ...
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87 views

Predicting directions of redox reactions [closed]

Hello! In this textbook example question, how come the chlorine reaction, which has the greatest reducing power will not react? If it has the greatest E of 1.36 V that means it has most reducing ...
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46 views

Electrochemistry - Understanding Diffusion Potential

I have a big problem trying to wrap my head around this for several hours and I cannot seem to make sense of it. I have to link this scheme with the 3 colored potential profiles on the bottom of the ...
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633 views

Is anode actually ever negative?

Disclaimer: This question comes from a physics student. I was studying electrostatics and I was wondering how to charge a conductor at home without any fancy furs etc. So an idea came to me: take a ...
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112 views

Why does changing the salt of the salt bridge effect the voltage produced in a galvanic cell?

My experiments results showed that the voltage decreases down $\pu{Group 1}$: $\ce{Cl-}$ salts in the salt bridge. All other variables were kept constant. $\ce{Zn}$ and $\ce{Cu}$ rods were used. ...
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276 views

Colour of VO3^-?

To aquire the yellow colour of vanadium ion, it must be present in a 5+ oxdiation state. This can be acheived (according to my textbook) by adding dilute sulfuric acid to $\ce{NH4VO3}$, then followed ...
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113 views

Can the 5+ and 4+ oxidation state of Vanadium ion exist independently?

From my class text book: The oxidation states of Vanadium ions 5+ and 4+ are shown in the compounds $\ce{VO2^{+}}$ and $\ce{VO^{2+}}$ respectively, whereas $\ce{V^{3+}}$ and $\ce{V^{2+}}$ are ...
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119 views

What is the meaning of parentheses in "NAD(P)H"?

If someone writes "NAD(P)H is oxidized by ...", does that mean they are referring to both NADH and NADPH? If so doesn't that lead to confusion when thinking quantitatively since the reactions may ...
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95 views

Galvanic Cell Temperature Dependence

I'm currently studying the temperature dependence of the following cell: $\ce{Cu_{(s)} + 2Ag^{+}_{(aq)} <=> 2Ag_{(s)} + Cu^{2+}_{(aq)}}$ ($E^⦵ = \pu{+0.46 V}$) Experimentally, I recorded the ...
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323 views

Understanding sodium hydroxide drain cleaner's exothermic dissolution of aluminum; does the aluminum need to be oxidized before it dissolves?

I'm not a chemist but I remember that the standard HF/nitric silicon etch used in micro-fabrication supposedly worked in two steps; the HF would dissolve the thin SiO2 oxide layer on the silicon ...
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2k views

How can AuCl3 exist?

The reduction potential for $\ce{Au^3+ + 3e- -> Au}$ is $1.503 \text{ V}$. The reduction potential of $\ce{Cl2 + 2e- -> 2Cl-}$ is $1.36 \text{ V}$. So, the $E^o$ for $\ce{2Au^3+ + 6Cl- -> 2Au ...
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Can Methylene Blue Detect Spoilage in Food?

Initially, there is already a product which is a sensor based on Methylene Blue, which can detect changes in oxygen levels in a packaging. However, as our thesis project, we decided to take on this ...
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56 views

Carbonyl chloride from stabilized chloroform treated with hydrogen peroxide

In our lab, chloroform contains 0.5–1% ethanol to prevent it from producing carbonyl chloride when exposed to UV light. Will the following reaction occur using such chloroform? $$\ce{CHCl3 + H2O2 -&...
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33 views

How are cells rechargable?

I have learnt that you can test if a reaction is thermodynamically feasible by testing if the cell voltage $E_\mathrm{cell}$ is greater than $0$. Surely, if a reaction is feasible, then the $E_\mathrm{...
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Is acidic character related to reducing power?

My book says that the acidic character of halogen acids increases on going down the group because the bond strength decreases, making it easier to release the $\ce{H+}$. But I also know that $\ce{HI}$...
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63 views

Finding molecular formula with limited information given

I have recently stumbled upon a question I can't seem to solve : Chlorine can also be used to synthesise a bromine-containing oxoanion that is mainly used in continuous or batch dyeing processes. ...
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18 views

Oxidative phosphorylation analogue

Does the salt bridge in galvanic cells resemble the ATP pump in the inner mitochondrial membrane? And if yes than did someone use this pH difference in harvesting this energy?
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492 views

Why is this reaction spontaneous in standard conditions?

To study if this reaction is spontaneous I proceed in this way: $$\ce{2H_{3}O^{+} +Fe ->H_{2} +Fe^{2+} + 2H_{2}O}$$ First I write the two semireaction: $$reduction: \ \ \ce{2H_{3}O^{+} +2e^{-} ->...
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208 views

How does increasing the Hydrogen Concentration of CuSO4 (electrolyte) affect electroplating of copper

I'm trying to find an answer as to how lowering the pH of the CuSO4 solution during electroplating of copper affects the amount of copper deposited onto the cathode. My very basic understanding is ...
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568 views

How can iodine oxidise hydrogen peroxide?

The following is mentioned in NCERT (government textbook in India used in all schools) under chemical properties of $\ce{H2O2}:$ (iv) Reducing action in basic medium $$\ce{I2 + H2O2 + 2 OH- -> 2 I-...
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179 views

What happens when you run house electricity through salt water?

What happens when you run house electricity (120VAC) through salt water? (with standard copper wires!) Well, in https://youtu.be/dcrY59nGxBg , an interesting experiment was conducted to find out! At ...
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1answer
2k views

Redox reaction: Iron(III) and Iodide ion [closed]

I'm a real beginner in chemistry and I'm currently reading about redox reactions. I'm quite confused about this simple redox reaction: ${\text{Iron(III) ion + Iodide ion} \rightleftharpoons \text {...
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2k views

Which gas is a oxidizing agent as well as a reducing agent?

I think it's Hydrogen, because, $\ce{PbO + H2 -> Pb + H2O}$ Here $\ce{PbO}$ is reduced to $\ce{Pb}$ and $\ce{H2}$ acts as a reducing agent. But, in $\ce{2K + H2 -> 2KH}$, hydrogen gains a ...
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350 views

Role of phosphoric acid in redox titrations

For redox titrations of $\ce{Fe^2+}$ versus $\ce{KMnO_4}$ or versus $\ce{K_2Cr_2O_7}$ , role of phosphoric acid is quite unclear to me. In dichromometric titration, $\ce{H_3PO_4}$ complexes $\ce{Fe^3+...
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909 views

What is the role of various additives in a titration of vitamin C with N-bromosuccinimide

In a titration to determine the amount of vitamin C in an orange juice sample, the following were mixed with water: oxalic acid potassium iodide starch acetic acid Then, the mixture was titrated ...
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29 views

Stability of cuprous iodide in aqueous solution

An aqueous solution of $\ce{Cu+}$ is usually unstable, but $\ce{CuI}$ is stable. Explain. $E^\circ(\ce{Cu^2+/Cu+}) = \pu{0.153 V}$ and $E^\circ(\ce{Cu+/Cu}) = \pu{0.521 V}.$ I found this question ...
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58 views

Why is NOₓ conversion low at fuel rich conditions in a three-way catalytic converter?

$$ \begin{align} &\text{Oxidation:} &\quad \ce{2 CO + O2 &-> 2 CO2}\\ & & \ce{``HC" + O2 &-> CO2 + H2O}\\ & & & \\ &\text{Reduction:} &\quad \ce{2 CO +...
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71 views

Is redox potential a valid term? [closed]

I mean doesn't every compound has its own different reduction and oxidation potential ? Or its just one potential that can be compared to understand which one will get reduced and which one will get ...
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94 views

Is there a relationship between acidity of the water solution and oxidation/reduction reactions?

What I want to know is if there is a relationship between the acidity of the water solution and redox reactions and if there is a relationship what favors the oxidation and what favors the reduction? ...
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18 views

What prevents inner-sphere electron transfer from oxalato-iron(II) to chloro-platinum(II)?

In this book (p. 237), when talking about the reduction of $\ce{[PtCl4]^{2-}}$ by $[\ce{(C2O4)2Fe]^{2-}}$, the author states that There is no easy route for imparting electrons onto the $\ce{PtCl4}^...
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1answer
1k views

What is the role of hydration enthalpy in oxidation?

My textbook says that the greater oxidising behavior of fluorine than chlorine can be attributed to the high hydration enthalpy of $\ce{F-}$ ions and the low dissociation enthalpy of $\ce{F-F}$ bond. ...
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25 views

Is it feasible to measure the pH of solution consisting of hydrofluoric acid, methanol and water using redox potential method?

Is it feasible to measure the pH of $\ce{HF}:\ce{H3COH}:\ce{H2O}$ solution using redox potential method? Can I use this method to calculate the $\ce{H+}$ ions in this solution and specifically, can I ...
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699 views

What does it mean to balance a redox reaction in acidic or basic mediums? [closed]

Until now it was clear to me what balancing a reaction was. Balancing redox reaction also make sense to me. What does it mean to balance a redox reaction in acidic or basic medium?
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171 views

Redox couple notation

How is the redox couple as it is written for the oxidation of $\ce{MnO4-}$, as $\ce{MnO4-,H+/Mn2+,H2O}$ correct? I agree that $\ce{MnO4}$ is being oxidized as it loses electrons (going from -1 ...
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135 views

Displacement by more electropositive metal in non aqueous environment

The more electropositive element should displace metal from it's salts' solution. This can be seen in reaction of copper salts with iron. But, if you try using for example potassium metal as the more ...

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