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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Effect of side reactions on galvanic cell using iron rod as anode and sodium chloride as salt bridge

We just made a galvanic cell on a chemistry lesson using iron and copper. We used a sponge soaked in $\ce{NaCl}$ solution as the salt bridge. The issue is that we measured a voltage way below the ...
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Titration procedure for measuring the antioxidant properties of EGCG

I am conducting a school-based research project into the antioxidative properties of green tea. Part of the procedure is to determine the concentration of antioxidant in green tea. This antioxidant is ...
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What product is created in a zinc - nitrate reaction?

Question: Place 2 mL of Nitric acid in a test tube and add a small piece of Zinc turning I thought that the overall net ionic equation would be: $$\ce{Zn + 2H+ -> Zn^2+ + H2}$$ Is this correct? ...
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combination of H2 and O2 after electrolysis [closed]

if we electrolysis water in a closed container H2 and O2 is formed, now as the container is closed both gases remain there when the electrolysis stop and water cool down will h2 and o2 remain in the ...
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1answer
30 views

Oxidizing properties of sulfuric acid: can it oxidize hydrochloric acid to chlorine?

Can $\ce{H2SO4}$ oxidize $\ce{HCl}$ to $\ce{Cl2}$? I know that $\ce{KMnO4}$ can do it, but my question is considering $\ce{H2SO4}$. In sulfuric acid, sulphur is in +6 oxidation state and in $\ce{KMnO4}...
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Acids give H+ in a reaction thus called reducing agent. But according to Lewis theory of acid and base, anything accepting pair of electron is acid [closed]

Now as acids accept electrons and so must be called oxidizing agent. and I feel it to be a bit contradicting. please clarify if any misconception
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How does copper oxidise alcohols?

Consider for example ethanol being heated in the presence of copper at 300 °C. How does it give ethanal as a product? Copper being in its elemental state (oxidation state 0). Since negative oxidation ...
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Temperature at which the reaction Oxalic acid + KMnO4 becomes autocatalytic

As described many times, the reaction between oxalic acid and potassium permanganate can be autocatalytic due to the production of Manganese ions. I've read that this only occurs at higher ...
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Why would electrode be positively charged in electrolysis?

From my understanding, a battery provides a driving force to pull electrons from the anode, thus the anode becomes positively charged. Suppose the anode is copper, the process should be as follows: $\...
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Will potassium permanganate react with ferric chloride?

I came across a question : Which of the following compound does not decolourise an acidified solution of $\ce{KMnO4}$? Answer was: After doing a bit of research I found that $\ce{KMnO4}$ oxidises $\...
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What will be the product of reaction of aniline with chromic acid?

I was trying to figure out what will be the the product on reaction of aniline with chromic acid. Answer: I know that $\ce{-NH2}$ will be protonated in acidic medium but I am unable to understand ...
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Comproportionation reactions

Is the following reaction a comproportionation reaction? $\ce{NH4NO3 -> N2O + H2O}$ The wikipedia definition says: Comproportionation or synproportionation is a chemical reaction where two ...
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What does the horizontal axis on cyclic voltammograms mean?

In cyclic voltammograms (like the one in the attached image) what exactly is the horizontal axis' voltage refering to? Is it the measured voltage between the reference electrode and working electrode? ...
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Does lead(II) chloride dissociate into Pb²⁺ and Cl⁻ ions in HCl?

While solving JEE Advanced 2020 (Paper 2) questions, I came across this particular question: Q.10 Choose the correct statement(s) among the following. (A) $\ce{SnCl2 · 2 H2O}$ is a reducing agent. (B)...
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What products are formed when KMnO4 and KI react with each other in “weakly basic” medium?

While solving JEE Advanced 2020 (Paper 2) questions, I came across this particular question: According to the final answer key, its answer is 6. In my chemistry book (NCERT Chemistry), the following ...
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55 views

oxidation number of oxygen in ozonide ion

What is the oxidation number of each oxygen atom in an Ozonide ion? by using usual method to determine oxidation number, I got average oxidation number of oxygen in ozonide ion as -0.33, however is ...
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concentration affect on cell potential

I conducted a galvanic cell experiment and increased the concentration of the anode (Mg) and the cathode was kept at standard conditions. I am unsure about why the cell potential decreased as the ...
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1answer
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Iron-II to iron-III change in complex formation

We have an iron dust sample, which is treated with hydrogen chloride in aqueous solution. The solution enters in a reaction with a sodium hydroxide powder, from which we obtain a precipitate. Could we ...
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Is it the solution energy or the reduction potentials (or both) that drives a galvanic cell?

I have received conflicting explanations for why the redox reaction in a galvanic cell occurs. Explanation 1: Some say that it occurs because the anodic metal dissolves more easily than the cathodic ...
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Balancing reaction between copper and nitric acid given the ratio of formed nitrogen oxides

Problem $\ce{Cu}$ reacts with $\ce{HNO3}$ according to the equation $$\ce{Cu + HNO3 -> Cu(NO3)2 + NO + NO2 + H2O}$$ If $\ce{NO}$ and $\ce{NO2}$ are formed in 2:3 ratio, what is coefficient of $\ce{...
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76 views

Balancing redox reaction of zinc and hot diluted nitric acid

I need to balance the following reaction: $$\ce{Zn + HNO3 -> Zn(NO3)2 + NH4NO3 + H2O}$$ I assigned all oxidation numbers: $$\ce{\overset{0}{Zn} + \overset{+1}{H}\overset{+5}{N}\overset{-2}{O_3}\...
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1answer
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How to convert cell diagram to a chemical equation?

How would one convert on the right side of the cell diagram: $$\ce{Zn(s) | Zn^2+(aq) || MnO4-(aq), Mn^2+(aq), H+(aq) | Pt(s)}$$ $$ \begin{align} \ce{Zn(s) &-> Zn^2+(aq)} \tag{ox}\\ \ce{MnO4-(aq)...
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1answer
55 views

Why did we introduce the concept of oxidation number in chemistry? [duplicate]

Isn't oxidation number a weird concept? It assumes complete transfer of an electron from a more EN to a less EN atom per covalent bond formed. This assumption isn't even true. We know that partial $δ^+...
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At what concentration would copper sulphate crystallise at 25 degrees Celsius?

I am doing an experiment on how increasing concentration of copper sulphate affects the voltage in a galvanic cell. The voltage increased as temperature did until 2M where it started to decrease. I ...
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Vanadium redox battery… why not nitrogen redox battery OR iron redox battery?

Vanadium redox battery operating on $$ \begin{align} \ce{V^2+ -> V^3+ +e-}\\ \ce{VO2^+ +e- +2H^+ -> VO^2+ +H2O} \end{align}$$ because Vanadium has multiple oxidation states. How about nitrogen ...
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28 views

Reasoning for redox reactions to be classified as such

Could anyone help me out solving this question regarding redox reactions? I am fairly new to this topic. Which of the following is a redox reaction? (1) $\ce{NaCl + KNO3 -> NaNO3 + KCl}$ (2) $\ce{...
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Adjusting redox reactions

$$\ce{KCl + KMnO4 + H2SO4 -> K2SO4 + MnSO4 + H2O + Cl2}$$ Attempt. I want to adjust this redox reaction, I've figured out that Chlorine and Manganese are the 2 elements that change thier oxidation ...
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How does the solvation of Zn lead to oxidation? (galvanic cell)

This video explains a causality of electric potential difference in a galvanic cell that's different from what I've understood. The video says that the $\ce{Zn}$ is dissolved into the water, and ...
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1answer
80 views

Does 50% hydrogen peroxide dissolve gold?

We have seen that the silver electrodes on a piezo element are being seemingly dissolved by exposure to our mixture of $50\,\%$ hydrogen peroxide. I was wondering if we were to switch to gold ...
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1answer
33 views

Copper plating with electrolyte not working (Cu(OH)2 vs CuSO4)

I've been experimenting using electroplating, and I recently made a solution by placing two copper pieces connected to a voltage source, in water. I suspect that this created copper(II) hydroxide, as ...
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2answers
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How do I write a balanced redox reaction for the oxidation of chalcocite [(Cu2S) (s)] by O2 (g) to form Cu2+ (aq) and SO42- (aq) [closed]

I'm not exactly sure how to get the oxidation and reduction half reactions. Any help will be much appreciated!
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Can you calculate the oxidation potential of an ion?

Is there any way to calculate the oxidation potential of [Fe(OH)(H2O)5]+? I am unsure if it can be done since I have only seen oxidation potentials provided for specific reactions of single elements, ...
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1answer
64 views

How do acids prevent ferrous sulfate from getting oxidised?

If $\ce{FeSO4.7H2O}$ is dissolved in an acidic environment, for example in 0.05 M aqueous solutions of methanoic or ethanoic acid, would that prevent it from getting oxidized if an oxidizing agent ...
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1answer
62 views

Balancing redox reactions

This has gotten me confused since long. Not all equations have clean half- reactions, some cations are in more than one compound while some anions are in some other compounds. Some reactions don't ...
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1answer
56 views

Question regarding the colour of Benzoic acid and Benzyl alchohol

This question is primarily based on the Cannizzaro reaction, where a base induces a disproportionation reaction of non-enolizable aldehydes (benzaldehyde, formaldehyde, etc) to form an alcohol and a ...
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2answers
38 views

Why transition metal chloride complex have lower reduction potential than metal aqua ions?

Why transition metal chloride complex have lower reduction potential than metal aqua ions? For example: $$ \begin{align} \ce{Au^3+(aq) + 3 e- &-> Au(s)} &\quad E^\circ &= \pu{+1.52 V}\...
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How does the addition of NaCl to the cathode side effect the potential of a voltaic cell: Zn(s) | Zn2+(aq) 0.1M || Cu2+(aq) 0.1M | Cu(s)

By addition of $\ce{NaCl}$ to the $\ce{Zn}$ side of the cell, I observed precipitation of $\ce{ZnCl2}$. I measured the voltage to $\pu{1.05 V}$ before adding $\ce{NaCl}$ to the cathode side, I then ...
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95 views

Determining iron content by titration

The redox reaction is $$\ce{KMnO4-(aq) + 8 H+(aq) + 5 e- -> Mn^2+(aq) + 4 H2O(l)}.$$ Where does $\ce{H+}$ come from in this reaction? What happened to $\ce{K+}$ in potassium permanganate?
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What does onset of oxidation mean in Cyclic volammetry

I've read a few posts on here on how to calculate onset of oxidations in Cyclic voltammetry. However, I dont know what it actually means when comparing the onsets of oxidations of two different ...
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Is there a generalize-able relationship between Ecell and T for a galvanic cell?

Is there a generalize-able relationship between Ecell and T for a galvanic cell (assuming constant concentrations of all components)? (ie: higher temp = bigger/smaller Voltage) Or is it entirely ...
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553 views

Why is bleaching with chlorine permanent but with sulphur dioxide temporary?

I was reading the properties of chlorine when I came across this statement: Chlorine is a powerful bleaching agent; bleaching action is due to oxidation. Chlorine bleaches vegetable or organic matter ...
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Understanding Pourbaix diagram

I am recently taking courses in environmental chemistry and I was introduced to Pourbaix diagram. I was taught that the lines in the Pourbaix diagrams are equilibrium lines. Lets take as an example ...
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1answer
93 views

Why does green ferrous sulfate solution change color to yellow upon addition of hydrochloric acid?

I was demonstrating the formation of $\ce{Fe(OH)2}$ precipitate at school when the light green $\ce{FeSO4}$ I was using reacted with dil. $\ce{HCl}$ turned yellow. This only happened with dil. $\ce{...
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1answer
63 views

Can water oxidize zinc?

According to this textbook, H₂O has lower reduction potential (-0.83 V) than Zn (-0.76 V). This mean zinc is unable to reduce water to hydroxide. If so, why this video demonstrate that by heating zinc ...
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2answers
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Confusion regarding $\delta$ charge compared with electronegativity

I heard on a lecture of an online site that, let us say, we have two orbitals (1 and 2). Now, it will be like a spherical cloud. Now, what they say is that Now, we can notice that for orbital number ...
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1answer
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Can we balance a redox reaction in basic medium just like as acidic medium and add OH- ions on both sides to cancel out H+ Ions? [closed]

My teacher told me that the method (which I mentioned above) is wrong but I find many references of saying the same method correct.
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1answer
76 views

Reduction of alcohol to alkane [closed]

I have been looking everywhere for hours now, and can't find anything on a simple lab reduction of an alcohol to an alkane that doesn't involve any "fancy" reagents such as tosylates, metal ...
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0answers
32 views

Will changing the salt in the salt bridge change the voltage produced in a galvanic cell?

I have used zinc sulfate and copper sulfate as the solutions, and used zinc and copper electrodes. For salt bridge I took lithium, potassium, calcium, sodium and zinc nitrates. The results are as ...
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2answers
97 views

Does increasing one of the electrolytes in a galvanic cell increase the voltage?

I would like to know how you could increase the voltage in zinc and copper galvanic cell: $$\ce{Zn(s) + Cu^2+ → Zn^2+ + Cu(s)}$$ I know that temperature and surface area is a factor that affects the ...
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32 views

Out of KCl, CaCl2, MgCl2, NaCl, which causes the greatest corrosion rate of iron and why?

I know that salts act as an electrolyte in a redox process and rusting of iron, where iron loses electrons and oxidizes, and oxygen gains electrons and reduces. I did an experiment with KCl, NaCl, ...

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