Questions tagged [reduction-potential]

For questions about the reduction potential (A measure of the tendency of a chemical species to acquire electrons and thereby be reduced) or its applications. Also see the tag [electrochemistry].

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644 views

Why is fluorine a oxidising agent?

An oxidizing agent pulls the electron cloud of the substance being oxidized towards itself, for example: $$\ce{F2 + 2 X- -> 2F- + X2}\qquad (\ce{X} = \ce{Cl}, \ce{Br}, \ce{I})$$ We also know ...
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102 views

Why do reference electrodes have porous frits or membranes as a salt bridge?

From what I understand, they act as a salt bridge between the reference electrode electrolyte and the analyte solution (in a potentiometric titration). But why do we use partially permeable membranes ...
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1answer
106 views

How does a Pt and reference electrode measure the cell potential in a potentiometric titration?

I'm trying to perform a potentiometric titration to determine the redox potential of a $\ce{Fe^3+|Fe^2+}$ couple. To do this, I am using an $\ce{Ag|AgCl}$ electrode connected to an inert $\ce{Pt}$ ...
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1answer
21 views

Can a half-reaction be oxidation if it has the higher reduction potential?

I am working on a problem that provides these two half-reactions: $$ \begin{align} \ce{Fe^3+ (aq) + e- &-> Fe^2+ (aq)} &\quad E^\circ_\mathrm{red} &= \pu{+0.77 V}\\ \ce{S2O6^2- (aq) + ...
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903 views

OF2 vs O2F2 oxidising strength

My teacher said that OF2 is the third most powerful oxidising agent after F2 and atomic O, but I think O2F2 should be even more oxidising, since it less stable than OF2. I just read on quora that O2F2 ...
3
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1answer
143 views

Compound having highest standard reduction potential

Which compound has highest SRP (standard reduction potential) value, e.g. the strongest oxidising agent? In most tables $\ce{F2}$ is at top with $E^\circ = \pu{2.87 V}$, but I've found a table listing ...
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1answer
82 views

Standard electrode potential

What is meant by the following: Electrode potential for $\ce{M^3+/M}$ Is it standard oxidation potential (SOP) or reduction potential (SRP)? What does a high positive or negative value for SRP and ...
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1answer
311 views

what should be the onset potential using cyclic voltammetry?

I am working for PEM fuel cell cathode material. I am confused regarding the onset potential determination for my catalyst (CV attached, fig 1 is complete CV while fig 2 is its zoom image for clear ...
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1answer
286 views

How to predict ease of oxidation or reduction for a given oxidising or reducing agent? [closed]

I have never understood which agent will be able to oxidize or reduce which type of reactants and yield which type of products will be formed. For example I want to know about DIBAL-H and how is it ...
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2answers
390 views

Proof of the chemical potential formula

My textbook as well as Wikipedia both state the formula $\mu_A = \mu_A^0 + RT\ln\{A\}$ which gives the chemical potential $\mu_A$ of a chemical species $A$ as function of the standard chemical ...
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1answer
5k views

Does the concentration affect the voltage in electrochemistry?

For my electrochemistry lab I'm using $\pu{10 mL}$ of $\ce{ZnSO4}$ and $\pu{10 mL}$ of $\ce{CuSO4}$ solutions connected with a salt bridge. I connect $\ce{Zn}$ metal and $\ce{Cu}$ metal to a voltmeter ...
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What exactly is formed when K2Cr2O7 is reduced?

I read on Wikipedia and in many books that when $\ce{K2Cr2O7}$ is reduced, it forms $\ce{Cr^3+}$ and a change is noticed from orange color to green. I want to know in what exact complex/salt/compound $...
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0answers
54 views

Can hydrogen plasma reduce carbon dioxide?

There are several studies describing usage of hydrogen plasma to reduce metal oxides. This is not yet widely adopted in industry, but it is of interest for environmental reasons (such as desrcibed in ...
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1answer
191 views

Calculating cell-potentials

I have measured the cell potential between a number of metals e.g. Ni, Pb, Al, Cu and Zn by constructing a galvanic cell and then used a voltmeter to measure the potential. Now, if I want to ...
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1answer
359 views

Why do potassium, rubidium, cesium all have lower standard potentials than sodium?

Why do potassium, rubidium, cesium all have lower standard potentials than sodium? Sodium has a higher charge density than any of them, so its enthalpy of hydration should be larger, right? The ...
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1answer
4k views

Changing Temperature of a Galvanic/Voltaic Cell: Should I wait for the electrodes to also change in temperature?

I'm conducting an experiment where I change the temperature of the sulfuric acid in a lead acid storage cell. My one question in controlling the variables is that should I let the electrodes also ...
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1answer
356 views

Galvanic/Voltaic Cell: Does Cell Voltage Change When A Resistor Is Connected?

I tried making a lead acid battery. After charging for about 10 minutes, I connect the voltmeter in parallel to the cell and see that there is around a 1.2V (which is quite lower than what I predicted)...
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1answer
56 views

Does silver oxidise in a pH 1 solution?

Consider submerging a plate of pure silver in a solution with $\mathrm{pH} = 1$. Does the redox reaction with hydrogen happen spontaneously? The composition of the solution is not given. My ...
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2answers
438 views

Lead-Acid Battery: Standard Electrode Potential

I'm making a lead-acid battery for an investigation. Since I only had sulfuric acid and lead electrodes, I decided to firstly run 2 lead electrodes through electrolysis in a sulfuric acid electrolyte. ...
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0answers
26 views

Potentiometric determination of fluoride

We did an experiment of potentiometric determination of fluoride ions. In several beakers we added several concentrations of NaF solutions and then we added water. We calculated with the electrode the ...
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1answer
292 views

Will nitrate be able to oxidise mercury?

We have the following data: \begin{align} \ce{NO3- + 3 e- &-> NO} &\quad E^\circ_1 &= \pu{0.96 V}\\ \ce{Hg^2+ + 2 e- &-> Hg} &\quad E^\circ_2 &= \pu{0.86 V} \end{align} ...
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291 views

Reduction potential of a complex

I am given the reduction potential of $\ce{Fe^{3+}}$ to $\ce{Fe^{2+}}$ as well as the dissociation constants $\ce{K_D}$ for a $\ce{Fe^{3+}}$ complex and a $\ce{Fe^{2+}}$ complex (effectively, the ...
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208 views

Ionizing radiation and oxidation without oxidizing agents

My knowledge on this subject is a bit rusty, so excuse me if I'm asking the wrong question here. I was taking a look at my high school chemistry books from many years ago, and I noticed that reduction ...
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300 views

Does Reduction Potential affect rate of electrolysis

I am currently doing a project on electrolysis, and I was wondering if the reduction potential (ie. $E^0$) will affect the rate of electrolysis. In other words, across different cells with differing $...
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1answer
379 views

How the Nernst equation is applied for electrodeposition? [closed]

For using the Nernst equation $$E = E_0 - \frac{RT}{nF}\ln\frac{[\ce{Red}]}{[\ce{Ox}]}$$ the concentrations of $\ce{Red}$ and $\ce{Ox}$ species are required. For the reaction $$\ce{Cu+ + e- <=&...
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For a system containing three reductants, can a combined reduction potential be determined?

I've modelled a system and found that there are three major complexes present at equilibrium, all of which I hope will act as reductants when I add an additional, oxidised species. Each of the three ...
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2answers
1k views

Single electrode potential measurement

My textbook says that in a galvanic cell, it's not possible to measure single electrode potential independently. Instead, a Standard Hydrogen Electrode is used as the system is under equilibrium. Can ...
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0answers
339 views

Acidified sodium sulfite in the reduction of iron(III) to iron(II)

Why does sodium sulfite have to be acidified in the reduction of $\ce{Fe^{3+}}$ to $\ce{Fe^{2+}}$? Does the acid act simply as a catalyst or is it necessary for the reduction process?
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1answer
61 views

Why is Cl2 only formed in acidic media?

If aqueous $\ce{NaCl}$ and $\ce{NaClO}$ are added together no reaction occurs, but if you add dilute acid to the solution $\ce{Cl2}$ gas is formed. Why does this reaction only happen in acidic media? ...
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1answer
552 views

Dependence of EMF of a cell on stoichiometry

In the reaction $\ce{Zn + 2Ag+ -> Zn^2+ + 2Ag}$ , my book says that the EMF is the difference between the standard reduction potential of $\ce{Ag}$ and $\ce{Zn}$. Shouldn't it be the difference ...
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50 views

What would an ecosystem based on reducing atmospheres be like?

I was wondering, what would it be like if instead of an oxidizing atmosphere like earth has, if an ecosystem had a reducing atmosphere instead? My professor told us that a system like that could be ...
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1answer
32 views

What is (approximately) the minimum exchange current for a potentiometric measurement?

Is there a rule of thumb for what should be the minimum exchange current to detect a certain redox couple in an aqueous solution? I would like to make a rough calculations to see whether any of my ...
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1answer
1k views

How to state something as strong or weak oxidising agents?

It is said that conc. $\ce{H2SO4}$ is a strong oxidising agent. Why is it regarded as strong? In case of acids, we say something that fully ionizes in an aqueous solution is a strong acid. But what ...
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2answers
410 views

Nernst equation calculations

I am stuck on 2 problems and would be grateful if anyone decided to give me a proper explanation as to how to solve them. I am not sure how to use the given information to correctly solve what is ...
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1answer
2k views

How does acidity affect electrode potentials?

What is the role of acidity in the decrease of formal potential of $\ce{Fe^{3+}$/$Fe^{2+}}$ in a sulfuric acid and phosphoric acid mixture? I've observed that the formal potential of the $\ce{Fe^{3+}$...
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1answer
482 views

Electrochemical series - when not at standard conditions

Is there a reason why this question's answer is treating it as if it is at standard conditions? Isn't it using 0.2M aqueous solutions, so the electrochemical series won't be valid for this question? ...
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2answers
320 views

Decreasing magnitude of peaks in cyclic voltammogram?

I'm in an instrumentation course and we covered cyclic voltammetry earlier in the semester and will be doing an experiment in CV next week. My question is this: If you have a reaction and sweep the ...
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1answer
5k views

Cyclic Voltammetry - HOMO and LUMO levels

I'm a physicist, so I apologize if these are obvious questions. I've carried out CV measurements on a few different types of material (with a ferrocene reference). I am interested in determining the ...
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78 views

What does the following sentence mean - “Li is least reactive but the strongest reducing agent among all alkali metals”

Isn't it contrasting? Is reactivity only concerned with kinetics of reaction ? PS - I am a high school student, probably I might be missing small detail!
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142 views

Periodic trends on half cell potentials

In a practice examination that I'm using to study for my upcoming midterm, one of the questions asks to choose three elements from a row of the periodic table and to give the order of the increasing ...
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1answer
888 views

What does a higher half cell potential mean?

I was taught in class that a positive large half cell potential generally meant that the reaction was more favorable. What exactly does this mean? Doesn't a reaction with potential 4V need a greater ...
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1answer
12k views

Reducing character of group 15 hydrides

It was given in my text book that reducing character of group 15 hydrides increases down the group. I am a bit confused about this. For $\ce{NH3}$ this is fine as I assume that: $$\ce{NH3 -> N + H^...
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1answer
632 views

Stronger reducing agent

Why H$_2$Te is a good reducing agent than H$_2$O . I think it should be opposite as in water , oxygen has only tendency to release electrons .
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Understanding Chemical Potential (Li-ion)

Can anyone help me to understand what the "Chemical Potential" is? I can see that in batteries the electrical energy is stored as "chemical potential", according to this: Li-ion ...
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1answer
4k views

Why does the Co³⁺/Co²⁺ couple have such a high reduction potential?

Cobalt is changing from $\mathrm{(3d)^6}$ to $\mathrm{(3d)^7}$ electronic configuration. What's so stabilizing about that? Just by reduction potentials this couple is more oxidising than hydrogen ...
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1answer
4k views

Reducing property of alkali metals [duplicate]

In my book it is given Reducing property increases down the group in gaseous or molten state . The increasing order is Li , Na , K , Rb ,Cs In according to me reducing property is based on ...
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1answer
388 views

On the unit of standard reduction potential and its independence of elements involved

Why is the standard reduction potential in units of volts (Joules/coulomb)? What does this tendency of a material to reduce has to do with the charge in coulombs? Also, why this number doesn't depend ...
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1answer
70 views

How does electrophoretic separation work in terms of separating soil into minerals?

I found this diagram and would like to know how it works with soil. Google searches yield protein/biology things, anyone know how this method would work with soil?
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1answer
255 views

Oxidation number vs charge?

From what I understand: *oxidation numbers: are the "act" of electrons moving while *charge: is what the atom "wants" to do with its electrons. - Can anyone please clear up the distinction ...
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1answer
344 views

Why the reduction potential of the reaction AgCl (aq) /Ag + Cl- is +0.22V

The point is $\ce{AgCl_{(aq)}}$ is the same as $\ce{Ag+}$ + $\ce{Cl-}$ (again, in water) So my reduction reaction would be $$\ce{Ag+ + Cl- + e- -> Ag + Cl-}$$ then the equation is simplified by ...