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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1answer
71 views

Why do batteries drain so quickly if they are forced to draw more current than they normally do?

When a battery is pushed to use twice the current it normally does, it lasts for less than half as long before dying... In fact, batteries often come with a 'C' rating that gives you an idea of how ...
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60 views

How does work from other sources affect Gibbs free energy of the system?

In most physical chemistry textbooks, Gibbs free energy is given like this: $$\Delta_\mathrm rG = \Delta_\mathrm rG^\circ + RT\ln Q\tag{1}$$ and Gibbs free energy is part of this three-way ...
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808 views

Does changing the electrolyte concentration in the electrolysis of water affect the speed that hydrogen gas is produced at the cathode?

I am currently completing a Year 12 Extended Practical Investigation. Due to the lock-down restrictions we are unable to complete our own practical experiment and have been given sample answers with ...
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43 views

Can I use activated carbon electrod as a reference electrod in a pH meter instead of using murcury? [closed]

Activated carbon is less expensive than mercury . They are recyclable . Mercury is toxic. Nowadays activated carbon is being used in supercapacitors,Li-ion battery.
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1answer
139 views

Cell voltage with different n factors

I’m a bit confused regarding cell potentials. If I have two half reactions each involving a different number of electrons, there are two ways I can see to calculate the net emf of their cell: Simply ...
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198 views

Why does an electrochemical cell work?

My textbook says that an electrochemical cell works because of difference in reduction potential of two metals which cause one to lose electrons and other one to accept them. If a salt bridge is not ...
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2answers
139 views

Supporting electrolytes and increased conductivity?

Hi a question about supporting electrolytes (SE) I hope you can help with. I found some related questions here through searching but looking for a simple answer (if there is one!): If SE are ...
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2answers
59 views

How does a battery create a potential differece (voltage)? [closed]

I'm 15 and recently started electronics and I just had a question about batteries. (I've been told by people on physics stack exchange to come here to have my question answered). From what I ...
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1answer
449 views

Standard electrode potential of copper disproportionation

I am having some difficulty with the below. It says the standard potential for $\ce{2Cu+ (aq) -> Cu (s) + Cu^2+ (aq)}$ is $\pu{0.36 V}$. The relevant half equations are: $\ce{Cu+ + e- -> Cu}$ (...
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43 views

In Na extraction, is Ca2+ of CaCl2 reduced in addition to Na+ of NaCl in electrolysis

In Na extraction from $\ce{NaCl}$, $\ce{CaCl2}$ is added in electrolysis to lower the melting point of the mixture to about $\pu{750 ^\circ C}$. But doesn't $\ce{Ca^2+}$ cation compete with the $\ce{...
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What surface treatment can turn nickel black?

Questions: The detailed surface treatment to turn nickel plated steel black. The reaction mechanism of the process. Methods: (preferred) Anodizing, oxidizing : The only black nickel oxide is $\ce{...
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1answer
89 views

if I have concentrated acetic acid (99%) what are the out put gases during electrolysis?

If I use concentrated acetic acid (glacial acetic acid($\ce{CH3COOH}$)) as an electrolyte. What ions are produced at the anode and cathode? Can I get ethanol with it ($\ce{C2H6O}$)? If not, what would ...
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1answer
57 views

What is the effect of putting salt on water during electrolysis [closed]

I want to decompose $\ce{H}$ ion and $\ce{O}$ ion by putting carbon electrode in the water, but it look so slow. What if I put sodium chloride? Would putting $\ce{NaCl}$ have effect on output gas($\ce{...
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359 views

Would a voltaic cell still work if you replaced both the cathode and anode with a carbon/graphite electrode?

for example, in this cell: Zn(s)|Zn2+(aq)||Ag+(aq)|Ag(s) if you replace the silver cathode with a carbon electrode, i know it would still transfer electrons, but if you also replaced the Zinc ...
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45 views

Why I get acidic solution at brine anode?

I have decomposed $\ce{NaCl}$ solution (brine) with electrolysis and yield $\ce{NaOH}$ at cathode, at anode I got acidic while expected was $\ce{NaClO}$ (alkaline) if it is $\ce{HOCl + HCl}$. Where ...
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1answer
491 views

Electrolysis with baking soda solution, a penny as the cathode and graphite for the anode

I set up an electrolysis experiment to show my kids and wanted to explain to them what is happening. My setup has a penny as the anode and graphite for the cathode. The solution is water with baking ...
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3answers
172 views

White snow-like powder below sodium hydroxide solution [closed]

I have created sodium hydroxide solution with half cell brine electrolysis but, finally I got white snow-like insoluble powder sank below sodium hydroxide. What should I do keep or remove it?
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1answer
62 views

Conductivity of molten or aqueous salts [closed]

If there is a 1M aqueous solution of 1 liter NaCl (aq), and the molar conductivities of the solution and the chloride ions were found to be $x$ and $y$ respectively, is it accurate to say that the ...
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30 views

What is the relationship between current flow and low AC voltages within electrolyte solutions

I have recently been trying to find references or textbooks which may explain the principles of electrical current conductance within an electrolyte solution when low AC voltages are induced. Does ...
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1answer
1k views

What happens when you put a battery in saltwater? [closed]

If somebody puts a battery in a salt solution, what path do the electrons take?
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193 views

How to find number of moles of HNO3 behaving like acid in a redox reaction?

In the reaction $(1)$, how to find the number of moles of $\ce{HNO3}$, which is behaving like acid? The reaction is given as follows: $$\ce{Sn + HNO3 -> Sn(NO3)2 + NH4NO3 + H2O} \tag1$$ To find ...
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134 views

How do you purify gases formed in electrolysis with a potassium hydroxide electrolyte?

I am interested in the $\ce{KOH}$ vapor that is released with my gasses during electrolysis. I have two questions. What would be the best place to start research on the $\ce{KOH}$ vapor produced in ...
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1answer
59 views

Overview of material characterization methods

I have been searching for quite some time now, but I feel like it is impossible to find some sort of chart where I can determine which characterization method (microscopy, spectroscopy, ...
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2answers
343 views

What is the physical explanation driving current flow in a concentration cell?

In a galvanic cell, current is driven because the species at the cathode is reduced by grabbing some electrons from the cathode. The cathode now lacks electrons so it pulls them from the anode. Now ...
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1answer
2k views

How is the formula of mean activity coefficient derived?

The mean activity coefficient is defiend as follows: $$\gamma_\pm = (\gamma_+\gamma_-)^{1/2}.\tag{1}$$ If Debye-Hückel equation $$-\log\gamma_i = 0.5z_i^2\mu^{1/2}\tag{2}$$ is used, then the mean ...
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35 views

Reason for no change in electrode potential in reference electrodes

Reference electrodes such as the saturated calomel electrode and silver chloride electrode have a constant potential because the $\ce{Cl-}$ concentration (or, to be more precise, the activity) is ...
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3answers
1k views

Why is the electrode potential for a cathode positive?

Electrode potential is the potential difference between the electrode and the surrounding electrolyte. If the potential of the cathode is positive this means that the potential of the electrode is ...
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55 views

Correlation between redox pseudocapacitance, surface area, and cell potential with metal oxide electrodes

I'm having difficulty intuitively reconciling two different ideas concerning metal oxide thin films in contact with aqueous solutions: 1) that charge storage by both redox pseudocapacitance and ...
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177 views

Cyclic voltammetry for irreversible reactions

I'm new to electrochemistry and I was wondering two things, sorry if these two problems are trivial but I just can't find anything close to this in the literature. First, the following reaction is ...
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312 views

Disproportionation of silver(I) in aqueous solution

Use the following equations to predict whether or not $\ce{Ag+}$ ions will disproportionate in solution: $$ \begin{align} \ce{Ag+(aq) + e- &-> Ag} &\qquad E^\circ = \pu{+0.80 V}\\ \ce{Ag^2+(...
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130 views

Proper method to electroplate aluminum?

I'm looking to plate some aluminum with silver using a basic solution. My first attempt was to use sodium carbonate to make silver acetate. I sped up the process using hydrogen peroxide. I used the ...
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1answer
302 views

Is it easier to oxidise iron(II) to iron(III) in acidic or alkaline solution? [closed]

Is it easier to oxidise $\ce{Fe^2+}$ to $\ce{Fe^3+}$ in acidic or alkaline solution? $$ \begin{align} \ce{Fe &-> Fe^2+(aq) -> Fe^3+(aq)}\\ \ce{Fe &-> Fe(OH)2 -> Fe(OH)3} \end{align}...
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1answer
133 views

Cis and trans electrodes

I have come across use of the terms cis and trans electrodes in the context of nanopores and driving charged biomolecules through a pore using an electric field [1]: FIG. 1. Drawing of the cis ...
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1answer
112 views

Expression for Gibb's free energy change for a cell reaction

According to Chemistry Libretexts, the Gibbs free energy change of a cell reaction is related to the cell voltage as $$ \Delta G = -nFE,$$ where $n$ is the number of moles of electrons passed and $F$ ...
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1answer
70 views

Silver "polish" with aluminum foil left a hard yellow coat [closed]

I cleaned my silver teapot with the aluminum foil-baking soda-hot water method. Usually this works well on my silver plated flatware. However, this time it left a hard yellowish coating. I was only ...
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1answer
564 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
394 views

Writing the overall cell reaction for the Calomel electrode

I an studying about electrochemical cells, and came across the Calomel electrode. It turns out that the half cell reactions and the overall reaction are as follows. Anode half-cell: $\text{Hg}_{2}\...
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1answer
112 views

How could burying a copper and zinc plate underground connected by a surface wire (earth-based Galvanic cell) promote crop growth?

Background: To quote a source: In the 1840s, W. Ross of New York reportedly obtained a severalfold increase in the yield of a field of potatoes when he buried a copper plate (5 ft x 14 ft) in the ...
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149 views

Convention in electrochemical cell notation

While writing the cell notation for a cell, doesn't one have to write the two states in which a species exists in a sequence appropriate to the reaction in which they participate? For example, in the ...
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1answer
270 views

What is the number of electrons being transferred in electrolysis of aluminum oxide? [closed]

$$\ce{ 2/3 Al2O3 -> 4/3 Al +O2}$$ As we know, to find the Gibbs free energy, we need to use this formula: $$ G= -nFE^\circ$$ What would $n$ be in this case? After breaking it down into the half ...
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1answer
79 views

Why the electrolyte is made up of the same metal which is being electro refined? [closed]

For example for the electrorefining of Cu the electrolyte is CuSO4... WHY the salt of the same metal is used as an ELECTROLYTE..??
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122 views

Why we do not add salt water to the batteries instead of acid? [closed]

Actually I was just thinking that since we add acid to the batteries to increase the conductivity but the thought simply crossed my mind that salt are strong electrolytes so there should be a good ...
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2answers
773 views

How do ions conduct electricity? [closed]

I mean to ask what do ions actually do while conducting electricity? Do they simply take up the electrons and transport it? If it is so, I do not understand how anions can take up more electrons if ...
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1answer
1k views

Does standard electrode potential depend upon temperature?

Does standard reduction potential depend on temperature? I am confused because my institute gives the definition for standard reduction potential as the potential that is measured at standard state ...
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3answers
151 views

Current with an ionic solution [closed]

For the last assignment of the school year, my science teacher gave the class questions about chem, physics, etc. The third question had me confused and I'll be thankful for all the help given. The ...
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1answer
70 views

Are electrostatic effects temperature dependent? [closed]

A charged particle like an ion, does its repulsive or attractive effect on other particles change with temperature? Are electrostatic effects temperature dependent?
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157 views

Role of potassium hydroxide in alkaline battery?

Is the role of potassium hydroxide ($\ce{KOH}$) in an alkaline battery to provide hydroxide for the reaction with zinc? Would the battery cease to work if $\ce{KOH}$ was removed and only $\ce{OH-}$ ...
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29 views

Why isn't the chemistry of a zinc-air battery (meaningfully) hindered by an activation energy barrier?

Virtually every source I've read pertaining to zinc-air batteries explain the chemistry of it either using these formulae or a simplified version of them: $$ \begin{align} &\text{Anode:} &\...
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78 views

Reduction potential for reduction of O2 to H2O2 in alkaline medium

I've read that $\ce{H2O2}$ is a good reducing agent in alkaline medium and can reduce $\ce{Fe^3+}$ ions to $\ce{Fe^2+}$ in alkaline conditions. But I need to verify this using the standard reduction ...
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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 ...

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