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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38 views

Nova 2.1 stop command (graphical user interface for electrochemical measurement)

We are doing an electrochemical polymerization of a semiconducting polymer and would like to try it as a pulsed square wave with defined frequency (i.e. 100 Hz) and duty cycle (i.e. 50%), but fixing a ...
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289 views

Some materials emit more photoelectrons than others - why?

Again, I'm a physicist turning to chemists (so bear with me). So I've been measuring some materials by changing the wavelength of the incident light on the material and I have a detecting tip like in ...
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51 views

Confusion about using Nernst Equation in Hydrogen Electrode [closed]

I was trying to calculate the potential of hydrogen electrode when $\pu{0.1 M}~\ce{HCl}$ was present in the hydrogen electrode at $\pu{300 K}.$ The chemical equation is $$\ce{H2 <=> 2 H+ + 2 e-}$...
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29 views

Is zinc chloride a viable substitute for zinc cyanide in brass plating processes?

I am owner/operator of a small plating company in Pittsburgh, Pa. I am having a problem with reddish color in brass plating process. Obvious cause is low zinc content in brass plating bath. Our ...
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1answer
36 views

Does nascent Oxygen/Hydrogen really exist or just or is it just electron from ionic equation? [duplicate]

Recently I was taught by my teacher that there is no such thing as nascent oxygen neither hydrogen. It just represents Electrons from ionic equations. Then he proceeds to give example of following ...
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1answer
42 views

More ions form pairs when concentration of acid increases, does that decrease the speed of reaction?

Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of ...
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16 views

Is there a difference in electrolsys rate limiting effects between electrodes of different area if one reverses the electrical polarity?

If one has two concentric stainless steel tubes with the small one being 1/2 the circumference and inside the other, and KOH for the electrolyte, then given the different surface areas between the ...
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39 views

Current density from overpotential

A current of $190$ mA is measure for a $2.5$ cm$^2$ electrode in contact with a solution containing M$^{2+}$/M$^{3+}$ metal ions at room temperature at a overpotential of +$180$mV. The transfer ...
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30 views

Electrode potential of Br2/HBr half cell

I am wondering if it is possible to find the electrode potential of such a half cell: $$\ce{Br2 (l) + 2 e- <=> 2Br-(g)}$$ The standard electrode potential is for $\ce{Br-(aq)}.$ However, is it ...
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30 views

Copper powder from aqueous copper sulfate solution help

I’ve been wanting to make copper powder for some homemade pyrotechnics. When placing an iron object in a copper sulfate solution, copper powder is produced. However, sooner or later, the reaction ...
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1answer
711 views

The open circuit voltage of a battery: Does it decrease with increase in pH of electrolyte while the voltage across a load increase?

Why does the open circuit voltage of a battery decrease with increase in $\mathrm{pH}$ of electrolyte, but the voltage across a load increase? I tested a cell which had aluminum sulfate as its anode ...
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Finding out the validity of the electrolysis of CaS to Ca(OH)2 to S in alkaline electrolyte

I would like to ask for the advice of chemists on how to go about validating a reaction that I have hypothesized as one stage in a chemical plant I am trying to improve. I want to find out whether a ...
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1answer
132 views

How can you have a reduction potential for a non redox reaction?

The standard reduction potential for the half cell $$\ce{FeCO3_{(s)} + 2e- <=> Fe_{(s)} + CO3^2-}\quad\quad(E^\circ=-0.756\ \mathrm V)$$ and the standard reduction potential for the half cell $$\...
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2answers
130 views

Is pH in a charged hydrogel and its supernatant solution constant?

Let us assume we deal with ideal systems without interactions. The gel phase and the supernatant solution phase are in thermodynamic equilibrium. The supernatant solution shall consist of different ...
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1answer
12k views

Why conductivity of electrolyte decreases on dilution, but molar conductivity increases?

I learnt that on dilution of an electrolytic solution, it's conductivity decreases. However, there is an increase in the molar conductivity of the solution. The book explained the reason by comparing ...
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1answer
682 views

Decrease in molar conductivity with increase in concentration

Why does molar conductivity $Λ$ for strong electrolytes decrease with increase in concentration? I mean, more concentration would mean higher number of solute particles present in the solution, and as ...
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1answer
46 views

What causes the voltage potential in a chemistry battery

Consider a simple chemistry battery: Zn and Cu with H2SO4 as the electrolyte. The electron will travel from Zn to Cu. And at the Cu side, H ion will get electron and turns to H2. If the circuit is ...
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1answer
6k views

Why does the copper anode dissolve?

In such a setup, the copper anode is known to dissolve. My question is, why? Does it not receive electrons from the $ \ce{OH^-}$ ions. And if you say that those electrons just flow to the battery, let ...
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1answer
79 views

Calculating Gibbs free energy change when the state of ions is unknown

Problem Calculate $\Delta G^\circ$ for the following reaction: $$\ce{Zn(s) + Ag2O(s) + H2O(l) -> Zn^{+2}(aq) + 2Ag(s) + 2OH-(aq)}$$ Given $E^\circ_{\ce{Ag+/Ag}} = \pu{0.80 V}$, $E^\circ_{\ce{Zn^{+...
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Intuition behind EMF independence of temperature for unit molarity solutions [closed]

The Nernst equation is given as: $$E= E^o - \frac{RT}{nF} \ln Q$$ Now, it turns out that if all the liquid components in the cell are unit molar i.e: of molarity one, then $Q=1$ and hence $\ln Q=0$ ...
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Anomaly in Faraday's constant measurements

I was reading someone's biography, where the writer stated his early interest in Faraday's constant measurements (this is set six decades ago). My understanding was that Faraday constant is a true ...
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2answers
112 views

Protons and osmotic potential

In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?
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240 views

Is there a potentiometric method for monitoring salt formation in organic solvent?

I work in a pharmaceutical R+D lab, and currently aim to develop a validatable potentiometric method for determining the optimal amount of acid to add to a basified small organic molecule for ...
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3answers
482 views

Pressure-dependence of electrolysis voltage

I'm trying to better understand electro-chemistry, so please explain why this second-kind perpetual motion device won't work. I guess it's safe to assume it won't work one way or another. There is a ...
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96 views

How to find standard electrode potential of a reaction resulting from two different reactions?

Q1) Calculate $E_{\ce{Cu+}|\ce{Cu}}^o=E_o$. Given that- $E_{\ce{Cu^2+}|\ce{Cu}}^o=E_1$ and $E_{\ce{Cu+}|\ce{Cu^2+}}^o=E_2$ Method 1- $$(i)\quad\ce{Cu^2+} + 2e^-\to \ce{Cu} \quad... \Delta G_1=-2FE_1$...
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Why does the reaction between copper(II) ion and iodide ion proceed even though the E_cell of the set up is negative?

(iii) Another example of a reaction that does not agree with the theoretical prediction is the reaction between $\mathrm{Cu}^{2+}$ and $\mathrm{I}^{-}$ according to the equation below. $$ 2 \mathrm{Cu}...
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1answer
571 views

Why is cell potential an intensive property? [closed]

I've heard that cell potential is an intensive property. However, we know that an intensive property does not depend on number of moles, mass, or concentration of the substance involved. However, when ...
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1answer
87 views

What is the meaning of thermodynamic tendency?

While giving a test, I encountered a question which was as follows Lead reduces $\ce{NO_3^-}$ into $\ce{NO}$ and $\ce{NO_2}$ depending on the concentration of $\ce{HNO_3}$ in solution. Assuming that $...
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1answer
134 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
103 views

Lead acid battery reduction and oxidation

During charging or discharging a lead acid battery both the positive and negative electrodes will undergo reduction and oxidation the same time. For instance during discharging process, the cathode ...
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2answers
121 views

Copper brightness change

In an electrolysis situation I have identified a slight brightness change on a copper electrode. What might have happened? I'm dealing with different experiments and this reaction occurs in some of ...
2
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1answer
83 views

Relation between standard silver-silver chloride electrode potential and solubility product of silver chloride

I learned that $E^\circ_\ce{Cl^-|Ag,AgCl}, E^\circ_\ce{Ag^+|Ag}$ and $K_\mathrm{sp}$ of $\ce{AgCl}$ are related as $$\boxed{E^\circ_\ce{Cl^-|Ag,AgCl} = E^\circ_\ce{Ag^+|Ag} + \frac{RT}{F}\ln K_\mathrm{...
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1answer
126 views

Current in a Lithium Ion Battery

I am trying to find the current transferred to the anode and cathode of a Lithium Ion Battery at different voltages. I know the temperature (approximately) of the battery, the battery's starting ...
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69 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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1answer
77 views

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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1answer
878 views

Oxidation of aluminum and manufacturing of electrolytic capacitors

My background is in electrical engineering. Recently I saw instructions on how to manufacture electrolytic capacitors at home by mixing sodium bicarbonate (baking soda) to distilled water, submerging ...
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60 views

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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1k views

Sodium Sulfate or Sodium Carbonate for electrolysis in water

I am not a chemist but I have a question regarding electrolytes in electrolysis. I have done a lot of reading but cannot find the answer I'm looking for regarding Sodium Sulfate (or Sulfide) I intend ...
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26 views

Optimal voltage for electrolysis [closed]

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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68 views

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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29 views

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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55 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
59 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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2answers
69 views

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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4answers
808 views

Is it possible to generate electricity by using two inert electrodes in a galvanic cell?

The Daniell cell has two active electrodes, meaning that both the copper and the zink electrodes participate in the redox reaction. However, in a lemon battery for example, the copper electrode is ...
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1answer
33 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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3answers
2k views

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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1answer
29 views

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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51 views

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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32 views

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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