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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56 views

Why does tennessine have a larger (predicted) electron affinity than nihonium?

According to Wikipedia, tennessine has an electron affinity (EA) of $\pu{+166 kJ mol-1}$ and nihonium $\pu{+67 kJ mol-1}$. Normally this would make sense since tennessine is in group 17 and nihonium ...
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Predicting possibility of oxidation by observing Standard oxidation potential

How can we judge possibility of oxidation by seeing the oxidation potential? OR What is the relation between Standard oxidation potential (S.O.P.) and quality of oxidation ? By quality I mean the ...
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Is this true for conductivity of mixture of two solutions equal to the sum of conductivities of each solution?

Suppose $\ce{Na2SO4}$ has a conductivity $\pu{2.6 \times 10^{-4} S cm-1}$ and on mixing $\ce{CaSO4}$ to saturation, the conductivity becomes $\pu{7.0 \times 10^{-4} S cm-1}$. So, Is the conductivity ...
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How to do a capacitively coupled electrode?

I have an AUTOLAB potentiostat: working electrode (WE, Pt wire), counter electrode (CE, Pt wire), reference electrode (RE, Ag/AgCl solid state). I would like to capacitively couple the potentiostat ...
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Optimal voltage for electrolysis

Reading Wikipedia for electrolysis, it provides the information that a potential of 1.23V is required to electrolyze water. How was that calculated? My intuition tells me that it is the sum of the ...
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Correct Definition of Absolute Electrode Potential

I thought absolute electrode potential is Galvani potential difference at the interface. However, it is given by following equation in John Bockris - Modern Electrochemistry (Ref.1): $$ E^M \mathrm{(...
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Do Lithium Iron Phosphate cathodes change color during charging and discharging while losing Li ions?

In an LFP battery, $\ce{LiFePO4 -> FePO4 + Li+ + e-}$. $\ce{LiFePO4}$ is described as a grey, reddish grey, brown, or black solid on wikipedia and $\ce{FePO4}$ a yellow-brown solid. If you had a ...
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53 views

Does the Li-F cell possess the highest possible voltage? [duplicate]

My question is quite straightforward: would a theoretical cell with fluorine and lithium yield the highest possible standard potential of all? The table of Standard electrode potential in Wikipedia ...
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1answer
58 views

How Does Voltmeter Sense/Measure All Potential Differences Present in an Electrochemical Cell?

Voltmeter is an instrument which measures electric potential difference between two points. When measuring electrode potential of some redox system (vs SHE for example), it is said that voltmeter ...
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1answer
27 views

Intuition for relation between electrode potential and reaction quotient

Consider the following reaction in a galvanic cell: $$\ce{X(s) + Y+(aq) -> Y(s) + X+(aq)}$$ According to the Nernst equation, $$E =E_\circ - \dfrac{RT}{F}\ln\left(\dfrac{\ce{[X+]}} {\ce{[Y+] }} \...
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Why is “activity” of gaseous component equal to its partial pressure but that of aqueous component its concentration?

While solving an electrochemistry problem I had to calculate the reaction quotient of this reaction: $$\ce{2Fe(s) + 4H+(aq) + O2(g) -> 2Fe^{2+} (aq) + 2H2O (l)}$$ It turns out to be: $$\ce{Q=\dfrac{...
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Ionic mobilities and conductivities of lithium and potassium cations in acetonitrile–propylene carbonate solution

Recently I calculated the ionic mobility and molar ionic conductivity values for $\ce{Li+}$ and $\ce{K+}$ cations in an acetonitrile–propylene carbonate binary mix solution (8:2 molar fraction ratio). ...
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Can stainless steel be electrically insulated with (oven-dried) Sodium Silicate Solution?

Can I electrically insulate stainless steel by painting Sodium Silicate solution on it and heating it to 200C for 30min or so? The solution should be conductive, and I've been told (to be verified) ...
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How the concentration of anodic half cell increases in galvanic cell?

According to my textbook Concentration of anodic half cell increases and that of cathodic half decreases when two electrodes are joined by a wire. I have also read that it is connected with a Salt ...
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Can a battery be built where several electrodes share the same electrolyte?

If you have two metals i.e. iron / copper and an electrolyte solution you can make a battery. Typically all of the designs have several of these connected in series to boost the output. But I have ...
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Why aren't electrons included in the equilibrium constant expression?

This might be elementary, but why aren't electrons included in the equilibrium constant for a half-reaction? For example, for $$\ce{O2 (g) + 4H+ (aq) + 4e- -> 2H2O(l)}$$ we have $$Q = \frac{(a_\ce{...
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Non - Polarizable Electrode/Interface

Non-polarizable electrode or interface is an electrode without charge separation on electrode/electrolyte interface or without double layer at which electrochemical reaction happens infinitely/...
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1answer
37 views

Best way to electrochemically etch metal [closed]

I've got some plates of cast iron that I'd like to etch electrically in a pattern by masking certain portions, as is commonly done for chemical etch. I found several sources all indicating that the ...
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1answer
45 views

Can there be a gas-phase electrolyte?

Reading the first paragraph in Wikipedia's I found one sentence particularly interesting: Some gases, such as hydrogen chloride ($\ce{HCl}$), under conditions of high temperature or low pressure can ...
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2answers
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What is the cathode in NiMH batteries

What is the cathode in $\ce{NiMH}$ batteries? I’m not sure if it is $\ce{Ni(OH)2}$ or $\ce{NiOOH}$. I’m confused because I thought that these batteries are like $\ce{NiCd}$ batteries except better (...
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1answer
18 views

Electrolytic cells optimum conditions

I am wondering why acidified copper sulfate is used instead of regular copper sulfate solutions in electrolytic cells? What benefit does the acidified solution give?
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How do I anodize bronze for thin film colors using electrolysis?

I am trying to change the color of the coins we have in Europe. I want to create patterns of certain colors. They are made from "nordic gold" (89% copper, 5% aluminum, 5% zinc, and 1% tin). ...
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does entropy of half cell reaction change with stoichiometry [duplicate]

the standard potential of the following cell is 0.23V at 288K and 0.21V at 308K. Pt|H2|HCl(aq)||AgCl|Ag calculate $\Delta{S}$ . I know that $\Delta{S}=nF(\frac{\Delta{E}}{\Delta{T}})$ here n is the ...
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How Does Internal Resistance of the Galvanic Cell Affect Voltage Drop of the Cell?

When galvanic cell operates or when current starts flowing in a circuit, voltage drops from electromotive force of the cell (EMF) because of internal resistance of the battery. There are three sources ...
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Why does the application of external mechanical pressure increase the performance of lithium-ion batteries?

Many electric vehicle batteries - specifically lithium-ion ones considered for this query - can be subjected to external mechanical pressure because it increases battery performance. What components ...
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1answer
27 views

Which is more efficient way to generate energy using hydrogen: direct hydrogen combustion or through fuel cell? [closed]

Which is more efficient way to generate energy using hydrogen: direct hydrogen combustion or through fuel cell? Please explain so that even a primary school student can understand.
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1answer
52 views

What is 'absorbance power' in electrochemistry?

I have been asked $\ce{250 mL}$ solution of unknown molarity of $\ce{CuSO4}$ in water was electrolysed using platinum electrodes. After the passage of a current $2 \times 10^{-3}$ ampere for $19.3$ ...
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30 views

Why do we need salt bridge in a cell during potentiometric measurement as there is no or minimum redox activity at electrodes?

In electrochemical cell, we need salt bridge to maintain electrical neutrility in both halves cells during redox reaction?. But in during potentiometric measurement, no or minimum current is drawn and ...
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42 views

what does Area(A) in Randles-sevcik equation refer to? geometrical area of electrode or electrochemical active surface area/

In the Randles-Sevcik equation, $$i_p = 0.4463 \ nFAC \left(\frac{nFvD}{RT}\right)^{\frac{1}{2}}$$ we have an area $A$ in the formula. is this the electrochemically active area or geometrical area? ...
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How can the difference between surface energy and electrostatic repulsion be calculated in electroplating?

When metals are electroplated unto surfaces, there are a myriad of forces at play. To set a clear example, if one were to electroplate a magnet with a diamagnetic metal such as bismuth, there will be ...
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39 views

Entropy change during electrolysis of water

Consider the electrolysis of water reaction: $$\ce{H_2O -> H_2 + 1/2O_2}$$ At room temperature and atmospheric pressure, the change in enthalpy of this reaction is $\Delta H = \pu{+286 kJ mol-1}$. ...
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1answer
95 views

Considering Gibbs energy or electrode potential to find disproportionation tendency

The following data was given (without the asterisks and footnote) asking us to find the oxidation states that would have a tendency to disproportionate - By tendency to disproportionate, I understood ...
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1answer
33 views

Conductance and concentration of a strong electrolyte

I learnt that with the increase of concentration, conductance of tr electrolyte decreases. While looking for the reason I found in my textbook that if concentration increase, amount of ions increases ...
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27 views

Thickness of proton exchange membrane (Nafion)?

I am looking into using a proton exchange membrane for a bio-energy cell experiment. Previous scholars have been using Nafion as a PEM to place between the anode and cathode (air-cathode). the ...
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27 views

In a perfect electrolytic cell, would the anode and cathode change by the same amount

If I had a theoretically perfect electrolytic cell, such as one with Copper anodes and cathodes, and a copper nitrate solution, over a given time period with a voltage applied, would the change in ...
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39 views

Potential difference between metallic electrodes in water

If I dip two pieces of metal in tap water I measure a potential difference between the two electrodes with a common digital voltmeter. For example, for Cu and Al I measured 0.55 V and for Cu and Fe I ...
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43 views

Why are conductance and conductivity additive in nature? [closed]

In my book, it is written that: $κ_{electrolytic solution} = κ_{electrolyte} + κ_{solvent}$ $G_{electrolytic solution} = G_{electrolyte} + G_{solvent}$ Where $κ$ and $ G$ are conductivity and ...
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What are the similarities / differences between the terms anode / cathode and oxidizing agent / reducing agent? [closed]

I'm kind of confused on how to distinguish the terms anode and cathode from oxidizer and reducer or oxidizing agent and reducing agent. Some references prefer to use one over the other in discussions ...
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1answer
84 views

Why Does Electrical Work Cause Changes in Internal Energy of the System? [closed]

If we look at system at constant temperature and volume which is galvanic cell, first law of thermodynamics states: $$ dU = dQ + dW'$$ Where W' is electrical work exchanged with surroundings and Q is ...
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What Does Electrical Work Represent in Context of Electrochemical Cells?

If cell operates reversibly than change in Gibbs energy of system equals electrical work of the cell. As far as I know electrical work is work done by electric field when charge moves between certain ...
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1answer
23 views

Can you create a temporary bond in between an atom and a filter by electrically charging the filter?

I want to be able to turn a filter on and off by electrically charging the filter so that it creates a temporary bond that blocks up the filter then, by discharging the filter, releasing the temporary ...
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1answer
42 views

Enthalpy of Reaction and Efficiency of Electrochemical Energy Devices

For electrochemical energy devices such as batteries or fuel cells working reversibly, efficiency is defined as: $$ \eta = \frac {\Delta_rG^⦵} {\Delta_rH^⦵} $$ Since cell operates reversibly Gibbs ...
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How does the membrane potential change so drastically during an action potential?

I understand that the Nernst potentials $$V = \frac{k_\mathrm{B}T}{e} \ln\left(\frac{c_\mathrm{out}}{c_\mathrm{in}}\right)$$ for all ions inside and outside a cell barely change when an action ...
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37 views

What is a suitable material for a cathode in electroplating experiment?

I am going to do an electroplating experiment, whereby I will be using a Cu(NO3)2 solution to plate onto a cathode. What is an easily accessible cathode which I can use for this? Would a strip of Ag (...
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1answer
54 views

How is it possible to electroplate using an Al3+ solution, when water is a stronger oxidant?

Suppose that I wanted to electroplate Al(s) onto a Cu(s) Cathode, (using an Aluminium Nitrate solution and Al(s) anode). At standard conditions, Al(s) is the strongest reducing agent, which is good. ...
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57 views

Why do galvanic cells need a salt bridge while electrolytic cells don't?

I see the questions of why a galvanic cell needs a salt bridge and why a electrolytic cell doesn't need a salt bridge being answered separately but I still can't grasp why you are not allowed to mix ...
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1answer
54 views

Need help to calculate results of an electrochemistry cell potential lab work

So, the lab work is this. I made an AgCl electrode of a silver wire by coating it with AgCl. This was done by electrolysis by immersing the wire in HCl and using platinum as a counter electrode and ...
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1answer
27 views

What determines the product at the anode/cathode of a electrolytic cell with an aqueous solution?

If you perform electrolysis on Aqueous Sodium Chloride of various concentrations, how does the product at the anode change but the product at the cathode does not? What is the mechanism behind this ...
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1answer
326 views

Homemade diode working mechanism

Hello, I will list the questions directly, if you want to know details please read below. As in the figure, we have water+baking soda in a plastic cup, there are 2 versions in figure that affects LED'...
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19 views

How are ions transported in solid state electrolytes?

Consider an inorganic solid state electrolyte in a solid state Li-on battery. It being solid means that the atoms or ions that make up the solid itself are not mobile. Then how do the ions move ...

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