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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35 views

Alternative Electrolyte Solution for Lead-Acid Batteries [closed]

I was curious about the possibility of creating a lead storage battery with dissolved sulfate compounds (like MgSO4, Na2SO4, (NH4)2SO4) in water as the electrolyte instead of sulfuric acid. From the ...
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53 views

Calculating the cell potential of a half cell from two half cell equations [duplicate]

I understand the premise of the question and how to solve it but I don't quite understand why I'm a factor of 2 out: Construct a potential diagram (at $\mathrm{pH} = 0$) for the reduction of aqueous $...
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52 views

Easiest/Fastest way to obtain a good quantity of fine Iron powder? [closed]

I am wanting to make a reasonable quantity (10-100g) of iron powder that I can use to visualise magnetic fields (by putting the powder in a thin layer between two transparent materials). The finer the ...
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32 views

In electrophoresis, are positive and negative molecules obviously separated?

I have just studied electrophoresis in biochemistry. The charged particles move to the oppsite charged electrodes whose speed is depended on their particle size. If that so, are negative and positive ...
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2answers
62 views

Copper anode dissolves in electrolysis of copper sulfate solution [closed]

I did an experiment with copper sulfate where you place two copper rods in an aqueous solution of copper sulfate. You apply an electric current and copper metal builds up on the cathode. I noticed ...
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Graphene in Lithium-ions batteries: why?

I have recently been reading about the amazing discovery of a super-material: Graphene. This one carbon-layer chemical is not only one of the most resistant materials ever known, but also one of the ...
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27 views

Methane Sensor electrochemical reaction

When using a methane sensor a voltage is applied and much like electrolysis if the voltage is above the decomposition potential a reaction happens. Flammable gasses like methane are easily oxidized ...
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1answer
65 views

Why is Sodium Transported Across the Cation Exchange Membrane in the Chlor Alkali Process?

In the Chlor Alkali Process, a sodium ion is transported across a cation exchange membrane to create NaOH in the Anode Chamber: The Half reactions are: 2Cl− → Cl2 + 2e− and 2H2O + 2e− → H2 + 2OH− and ...
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Is there a way to theoretically estimate the overpotential losses in a battery?

Me and my team are currently designing a battery and are looking to do some pre-experimental analysis of different battery chemistries based on their overpotential losses. I am aware of the Butler ...
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1answer
40 views

Cell potential for redox titration of iron(II) with cerium(IV) [closed]

Calculate $E_\mathrm{cell}$ for an electrochemical cell consisting of SCE and a platinum wire indicator electrode dipped in a titration vessel containing $\pu{25 ml}$ $(\pu{0.01 M})$ solution of $\ce{...
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53 views

How does current start to flow when galvanic cell is first connected?

Using the Daniell Cell as an example, where in the steady state we expect zinc to be oxidised and copper to be reduced spontaneously due to the overall reduction in Gibbs free energy, how does the ...
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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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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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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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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
82 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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91 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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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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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
51 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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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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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
39 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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29 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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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
83 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
92 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
42 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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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
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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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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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Conducting cyclic voltammetry in an air sensitive manner

Does anyone have suggestions on ways to conduct cyclic voltammetry on an air sensitive material without shipping the entire set up into a glovebox? This is for redox active organometallic compounds.
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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
52 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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97 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
86 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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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
106 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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36 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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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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194 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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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
86 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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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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94 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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56 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
54 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
60 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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85 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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