Questions tagged [electrochemistry]

The branch of chemistry that deals with the study of redox reactions and how they can be applied to generate electricity (in electrochemical cells) and to carry out non-spontaneous reactions using electricity (electrolysis).

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5
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1answer
868 views

Variable oxidation state of transition metal ions

Transition metals can form stable ions with different oxidation states. But I am confused why doesn't only the most stable state exist. Let me clarify my question more: $$\ce{Ti^{2+} -> Ti^{3+} + ...
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1answer
493 views

What does the slope of a Levich plot represent?

I know that the limiting current is proportional to the square root of the rotation speed, but what does the slope of the plot represent?
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2answers
251 views

What's the voltage of a battery?

The definition of voltage I'm familiar with is the amount of electric potential energy per unit charge at a location. My prof defined the voltage of a battery to be the amount of potential energy ...
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1answer
315 views

Voltaic and electrolytic cells

Why more attractive metals will be oxidized? Aren't they being reduced, because they attract and receive electrons from negative polyatomic ions? So they will be anodes, where oxidization occurs. Why ...
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4k views

Gas Electrode Working

How does a SHE electrode work? Does the $H_2$ gas get absorbed on the platinum electrode? How is it reduced? How are electrons transferred from the adsorbed gas to the solution? How is $H^+$ ...
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1answer
4k views

Electrolysis of aqueous lead nitrate

When going through one of my chemistry textbooks, I saw that the electrolysis of aqueous lead nitrate led to oxygen being formed at the anode and lead being formed at the cathode. However, in school, ...
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120 views

What is the relationship between migration and the potential of double layer theory?

Double layer theories like that of Gouy-Chapman give the electrostatic potential $\ \phi\ $ in solution. For a symmetrical electrolyte and small potential drops $\ \phi\left(x=0\right)-\phi\left(x\...
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1answer
237 views

Difference between non-thermal and thermal ionized gases

Why or when does non-thermal plasma become thermal? How do we know before hand if the ion temperature will differ from the electron temperature, on what parameters does it depend - where is the ...
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1answer
738 views

Deriving goldman equation

So I've been trying to follow the derivation of the Goldman-Hodgkin-Katz equation on Wikipedia (https://en.wikipedia.org/w/index.php?title=Goldman_equation ) - I can follow it through after it sets up ...
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124 views

Discrepancy in current inside an electrolytic cell

Suppose A(+)B(-) type fused salt is present in an electrolytic cell (not electrochemical cell). Let n electrons be entering the cell per second. Since each A(+) requires one electron to discharge, so ...
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50 views

Electrochemistry lye quality

With the following setup: plastic container, water (impure), pencil (anode), tin foil (aluminum, cathode) and solar panels supplying electrical charge (roughly 36v at about 400-800ma), with the ...
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1answer
93 views

Electrolytic cell chemical composition during/after charging?

I have a pot with some (bottled) water and added (sea) salt. It has a pencil (graphite) and tin foil (aluminum). The pencil is connected to the positive outlet of a solar panel and the tinfoil is ...
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2answers
9k views

Why can we disregard stoichiometric coefficients when computing reduction potentials?

Example: A $Cd // Cr$ Galvanic cell has redox half reactions: $\ce{Cd^{2+} + 2e^- -> Cd}$ $E_{cell}$ = -0.4 $\ce{Cr^{3+} + 3e- -> Cr}$ $E_{cell}$ = -0.7 Balanced equation of reaction ...
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1k views

How do I derive the Nernst equation in the case in which R is absent?

Does anyone know what the intermediate calculations are to obtain equation 1.4.14? Taken from Fundamentals and Applications (Bard) page 31 To be more precise, how to obtain (1.4.14) from $\frac{...
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1answer
250 views

What is made at the copper cathode when electrolyzing water?

I just electrolyzed water with $\ce{NaHSO4 -> HSO4- <=> H+ + SO4^2-}$ with copper electrodes. At the anode this reaction happened: $\ce{Cu -> Cu^2+ + 2e-} \hspace{26 mm} E_0 = -0.34V$ ...
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1answer
7k views

how is the relation between Gibbs free energy and cell potential?

First of all what is exactly Gibbs free energy in regards to an electrochemical process? How can we visualise it? How does Gibbs free energy change in an electrochemical reaction? How is it related to ...
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1answer
108 views

Does anyone know where I can find the reaction rate coefficient and design equation for the electrolysis of brine and sodium hydroxide solution?

equation 1) $\ce{2 Cl^{–} -> Cl_2 + 2e^{-}}$ equation 2) $\ce{2 H2O + 2 e^{–} -> H2 + 2OH^{–}}$ These equations are the key reactions in the chlor-alkali process. I want to model a reactor ...
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1answer
69 views

Electrochemical characterization of benzenesulfonamide

I'm trying to elucidate current peaks for benzenesulfonamide, using an acetic acid-sodium acetate 0.1M buffer at pH 5.5 as electrolyte. When doing cyclic voltammetry, I get a voltammogram similar to ...
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1answer
170 views

What prevents the anode from corroding in electrolytic organic reactions?

An electrode can be plated by having a solution full of electrolyte, using the the metal that will receive the plating as the cathode, and the metal doing the plating as the anode. Current is put ...
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2answers
827 views

How much electricity could be generated by a person's stomach acid?

Motorola has a device that is powered by stomach acid. Given that a battery consumes the electrolyte as it generates a charge, how much power could be generated using a device such as this? Let's ...
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1answer
934 views

Silver electrorefining

Ok, so let's say I have raw silver which is polluted with a bit of gold, copper and lead. So through electrorefining I want to make pure silver out of it. Let's say I have it all in an acidic ...
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2answers
3k views

Balanced reactions at the anode and cathode [closed]

A current of 2.25 A is applied to $\ce{NiCl2}$ solution A. Write the balanced half reaction that takes place at the anode B. Write the balanced half reaction that takes place at the cathode Can ...
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2answers
1k views

Can bromide ion reduce ferric ion?

Can bromide ion reduce ferric ion ? Just a query. In my opinion it can since bromide ion can undergo oxidation. Is my answer correct?
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5k views

Similarity between Ecell and equilibrium constant Kc

$$\ce{Cu^{2+} + Zn<=>Zn^{2+} + Cu}$$ $K_c=1.9*10^{37}$ $E_{cell}=1.1V$ I know that they both suggest that the forward reaction is going to completion but can someone please tell me a bit ...
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128 views

Intuition for electrode potential

If I connect a zinc half cell (Left hand side) and a copper half cell (right hand side), I get an E cell value of 1.1V taken from the voltmeter. If I replace the voltmeter with a light bulb, I will ...
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1answer
3k views

“Number of moles of electrons involved in the reaction” for hydrogen cell

I understand we can calculate the maximum work done by the electromotive force (driving electrons through a cell) by multiplying the potential of the cell with the charge of one mole of electrons (...
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2answers
565 views

What are high throw solutions?

I am trying to make a copper sulfate electroplating solution. I came across a document (Schlesinger and Paunovic 2011) which mentions the amount of copper sulfate that should be added to water to ...
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2answers
11k views

Derivation of relationship between Gibbs free energy and electrochemical cell potential

Why is $\Delta G=-nFE?$ I don't understand what the motivation is behind this definition. Was it derived or just given? The textbook provides no justification for this equation. In fact, much of the ...
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1answer
313 views

During electrolysis, why are the products attracted to the cathode?

Take the electrolysis of Lead(II) bromide: We can write it as two half-reactions: $$\ce{Pb^{2+}(l) + 2e^{-} \rightarrow Pb(l)}$$ $$\ce{Br^{-} \rightarrow Br + e^{-}}$$ In the electrolysis reaction,...
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1answer
3k views

Vertical lines in a Pourbaix Diagram

I know that because of the absence of the hydrogen ions in a reaction ($n_{H+} = 0 $) , the correspondent E-ph line have to be horizental , but what exactly the types of reactions (if there is) that ...
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1answer
597 views

Electrode potentials at interfaces?

My questions relates to the fundamental concept of electrochemistry, more specifically the electrode potentials. 1) First, why is there a potential difference at the interface of two phases? ...
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73 views

Reaction of an electrode

Why is the cathodic reaction of $I^-/AgI/Ag$ is $$\ce{AgI + e- -> Ag + I-}$$ but not, $$\ce{Ag+ + e- -> Ag }$$ whereas, in $Ag/AgCl(s)$, $KCl$(0.2M); it is $$\ce{Ag+ + e- -> Ag}$$
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1answer
276 views

How do the stored chemicals in batteries drive electronic current from their terminal to outside devices?

I have got around to at least read on Wikipedia, and it does not clarify how this works in any sensible manner. I wondered how the chemicals make electrons "move". How is the basic understanding of ...
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1answer
226 views

chemically inert molecule with piezoelectric properties

For a research project, I'm looking into existing chemical molecules that have the following properties: It is mostly chemically inert, safe for animals and children It exhibits piezoelectricity - ...
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1answer
78 views

In a battery what would happen if you had a perfectly uniform and pure cathode?

I have been watching some videos on how batteries work and they seem to talk about the cathode being the most important. I also watched another video a long time ago and while my memory is blurred it ...
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1answer
146 views

Why do batteries specifically vent *hydrogen* in the event of abuse?

When a battery is subject to overcharging or overdischarging (including attempts to recharge a primary cell), it may vent hydrogen. It seems that every type of electrochemical battery I've read about ...
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1answer
596 views

Electrochemical Cell

Now in an electrochemical cell , we make use of the fact that whenever there is a potential drop , electrons will flow from lower to higher potential as for a potential drop , there must be an ...
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1k views

Sulfuric Acid Resistance / Conductivity

I diluted sulfuric acid in deionized water in order to get a 10% $\ce{H2SO4}$ solution. I was going to use this solution as a cathode of a porous sample to measure its electrical properties. However,...
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507 views

What's the chemistry behind only charging a Lithium-ion battery to 80% capacity at most, to increase its lifespan?

What's the chemistry behind only charging a Lithium-ion battery to 80% capacity at most, to increase its lifespan? Over on the Skeptics StackExchange, a question has come up about charging Lithium-...
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1answer
2k views

How do I calculate partial pressure here?

I need some help with partial pressures of reactions for a fuel cell project. The overall reaction for a fuel cell is $$\ce{H_{2} +\frac{1}{2}O_{2}->H_{2}O}$$ Which means that the mole fraction ...
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171 views

Lewis model and modern physics

Electron affinity of chlorine = -349 kJ per mole. And, first ionization energy of sodium = 496 kJ per mole while energy required for combining= 147 kJ per mole. Isn't it a contradiction against ...
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1answer
462 views

Why do aqueous solutions always have to be electrically neutral?

I was reviewing some analytical chemistry and stumbled upon a section that explained the imperfection of using a salt bridge. It said that the using dissimilar ions is a problem because in, for ...
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1answer
309 views

Why does electrolysis take so much time?

What makes electrolysis or electroplating take so long ? What stage takes longer when ions are attracted to electrodes or when they gain or lose electrons at electrode. And if we are talking about an ...
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1answer
119 views

Is it possible to form bubbles of ionized hydrogen and ionized oxygen under the right pressure/temperature conditions during electrolysis of water?

When we run a current through water (pure or not), $\ce{O_2}$ forms at the anode while $\ce{H_2}$ forms at the cathode. If I understand correctly, as water is already slightly ionized, $\ce{H}$'s snap ...
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1answer
152 views

Measuring distance in a conductive liquid

What is needed to measure distance between two electrodes imersed in seawater ? I have tried measuring the voltage across the path (a suposed resistance) with a constant current source (about 10uA) ...
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1answer
726 views

Electronegativity

Why is the Electronegativity difference for atoms in bonding uncertain while determining what the compound will be? According to the IB(International Baccalaureate) they say that the ...
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1answer
119 views

What is a 'Trace Crossing'?

I'm reading about electrodeposition of conductive polymers in a chemistry textbook, and the author mentions 'trace-crossing' in the 'potentiodynamic response'. From the context I can figure out that '...
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1answer
189 views

Thought Experiment: Applying a high frequency high voltage to methane

I am in the process of constructing a kitchen waste digester (vegetable/fruits) from which, hopefully, over time adequate methane may be collected to burn. The digester won't be complete for several ...
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2answers
2k views

Can we separate positive ions from negative ions in a solution?

Can we make a solution containing only positive ions by using electrodialysis but instead of using 2 kinds of membrane (one blocks the positive ions and one blocks the negative ions) we can use only ...
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42 views

Would the detaching of dendrites from electrodes in a cell, result in the crystal dissolving back into the electrolyte?

Dendrites that form on the electrodes of cells shorten the cell's lifetime, and result in reduced capacity before the end of life. If the dendrites could be detached from the electrode, would they ...