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).

Filter by
Sorted by
Tagged with
-1
votes
1answer
28 views

Why does increasing the number of pieces of string as a salt bridge decrease the voltage in a voltaic cell?

I recently conducted an experiment using string that had been submerged in saturated salt solution as a salt bridge in a voltaic cell. As i increased the number of pieces of string (increased surface ...
-2
votes
1answer
38 views

Why is cell potential an intensive property?

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 ...
1
vote
1answer
54 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}\...
51
votes
7answers
516k views

Positive or Negative Anode/Cathode in Electrolytic/Galvanic Cell

In a galvanic (voltaic) cell, the anode is considered negative and the cathode is considered positive. This seems reasonable as the anode is the source of electrons and cathode is where the electrons ...
0
votes
2answers
2k views

Salt Bridges/Porous Disks

I am slightly confused about the concept of a salt bridge/porous disk. I understand that these are necessary in a galvanic cell since there is a charge buildup and the salt bridge and porous disks ...
0
votes
0answers
27 views

Cyclic voltammetry - reverse scan

Disclaimer - my knowledge of CV is from textbooks and YouTube videos, haven't ever done an experiment. Hence the dumb questions below: During the 'reverse' scan, does the polarity of the electrodes ...
2
votes
1answer
110 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 ...
4
votes
1answer
73 views

In a battery, what happens to LiCoO2 when the lithium leaves? It becomes CoO2?

What chemical compound exists at the cathode of a lithium-ion battery when the lithium is not there? The cathode is usually described as $\ce{LiCoO2}$, so does it become $\ce{CoO2}$? $\ce{CoO2}$ ...
-1
votes
3answers
1k views

How does electrolytic conduction depends on the size of ions & their solvation?

The textbook says, The smaller the effective size of the ion after solvation, the greater will be its conducting power." But, on the Internet, it is explained as follows: Radius decreases, ...
0
votes
1answer
90 views

Nernst equation and equilibrium

I am currently stuyding electrochemistry, and recently I've stumbled upon a problem where one is supposed to calculate the concentration of Fe3+ ions after a solution containing Fe2+ was titrated ...
0
votes
1answer
44 views

Aluminium, Carbon, Aluminium Sulphate battery. What's the reaction?

I made galvanic cells from the following items (while trying to do something else), and they give between 0.6 V and 1 V per cell. Aluminium foil – negative terminal Carbon (these work: charcoal ...
0
votes
0answers
25 views

How can I calculate the diffusion limiting current density?

I know the concentration of a substrate in a water solution and I want to calculate the diffusion limiting current density for an electrode that reacts with that substrate. What are the steps to ...
1
vote
1answer
59 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 ...
5
votes
1answer
29 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?
-2
votes
1answer
23 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..??
-1
votes
2answers
49 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 ...
-1
votes
2answers
64 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 ...
0
votes
3answers
369 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 ...
0
votes
1answer
41 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 ...
0
votes
3answers
135 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 ...
1
vote
1answer
50 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?
-1
votes
0answers
24 views

Alkaline battery, is hydroxide ions or the zinc metal the source of released electrons?

An alkaline battery is often said to derive its energy from the zinc metal, but it seems like the potassium hydroxide could be the source of the electrons just as well. In the anode reaction, ...
-1
votes
1answer
39 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 $\ce{OH-}$ ...
2
votes
1answer
20 views

Determining the Energy Density of a Battery given the anode and cathode

everyone, I'm using nanohub's introduction to the material science of rechargeable batteries course to do some self-studying until I can go back into the lab. On one of the practice problems, it asks ...
2
votes
1answer
20 views

What is the diffusion limiting current density in comparison to rotating electrodes or fuel cells with pumps/stirrers?

If an electrolytic fuel cell operates in an acidic liquid electrolyte and electrons are supplied to a catalytic electrode so that the protons in the liquid solution will react and produce hydrogen gas,...
0
votes
2answers
106 views

In a galvanic cell, why do electrons move through the wire from zinc to copper?

I understand that there is aqueous $\ce{Cu^2+}$ in this scenario which pulls on the electrons from the zinc causing the electrons to move through the wire, but how does the electronegativity of $\ce{...
2
votes
0answers
27 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:} &\...
1
vote
1answer
37 views

Copper brightness change

In a electrolysis situation I have identify 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 them. ...
0
votes
0answers
28 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 ...
0
votes
1answer
52 views

electrochemistry experiment

something strange. i made an electrochemistry experiment in which i have measured the potential of cell: Ag, AgCl | (1M)KCl ║ [Fe(CN)6] 3-, [Fe(CN)6] 4- | Pt with different concentrations of Fe+2/Fe+...
-1
votes
1answer
32 views

How does the charge imbalance affect the cell reaction when there is no salt bridge in a galvanic cell?

As mentioned in the answers to this question Why is it important to use a salt bridge in a voltaic cell? Can a wire be used? a salt bridge is used to keep the two half cells neutral. i understand how ...
0
votes
3answers
1k views

Do We change sign of electrode potential when reversing an equation?

I have a cell equation as: $$\ce{2Cr^0 + 3Cd^2+ -> 2Cr^3+ + 3Cd^0}$$ I am provided the standard reduction potentials as: $$\begin{align}\ce{Cd^2+ + 2e- &-> Cd} && E= \pu{-0.4V}\...
2
votes
1answer
615 views

What does the osmotic pressure do in an electrolytic solution?

I have learnt that in an electrochemical cell, the osmotic pressure in the solution hinders the flow of ions from the electrode to the solution, rather some ions may accumulate on the electrode ...
-2
votes
1answer
41 views

Rusting of iron is quicker in saline water than in ordinary water [duplicate]

I feel so because, saline water has more more electrons and because of that there will be oxidation will take place faster and hence the overall process will speed up. Is this explanation good enough ...
3
votes
1answer
366 views

How to find the potential of a mixed Iron/ Cer solution?

Given the following half-reactions: \begin{align} \ce{Ce^{4+} + e^{−} &-> Ce^{3+}} & E° &= \pu{1.72 V}\\ \ce{Fe^{3+} + e^{−} &-> Fe^{2+}} & E° &= \pu{0.771 V}\\...
2
votes
2answers
74 views

How does overvoltage affect the products of electrolysis?

When you electrolyse an aqueous solution of $\ce{NaCl},$ the product formed at cathode is $\ce{H2}$ gas (preferential discharging), but the product formed at anode is $\ce{Cl2}$ gas. According to ...
2
votes
0answers
58 views

What happens to a flat lemon and can it be recharged? [closed]

A lemon can be used as a battery, and is often used to teach kids the basics about electricity and chemistry. This is due to their acidic and electrolytic properties. What happens to a lemon when it ...
0
votes
0answers
39 views

Aluminum Hydroxide electrolysis

Does molten Aluminum Hydroxide break up to aluminum, water, and oxygen by electrolysis? It's easy to write the equation $$\ce{4Al(OH)3 -> 4Al + 6H2O + O2}$$ but is this actually possible?
6
votes
2answers
14k 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 ...
0
votes
1answer
62 views

Calculation of the cell potential of a lemon battery experiment

I have the following problem that I would like to get checked. I’m told to calculate the cell potential of a simple lemon battery experiment. After Finding out the oxidizing agents and the reducing ...
5
votes
1answer
150 views

Electrolytic Refining of Silver Nitrate

I read that the electrolytic refining of Silver is done using dilute silver nitrate as an electrolyte and a small percentage of free $\ce{HNO3}$. The following reactions are possible at the anode: $$\...
0
votes
1answer
31 views

How does electrolytic conductance depend on solvation?

My textbook says: If the ions are strongly solvated their effective size will increase and hence their conductance will decrease P.s after reading my textbook, I don't think I'm sure what solvation ...
3
votes
4answers
384 views

Where to buy/How to build a Devanathan-Stachurski cell?

I'm preparing to do some hydrogen permeation tests to calculate the diffusivity of some iron samples. I would like to do this using the Devanathan-Stachurski cell, which consists of two cells, one ...
1
vote
0answers
65 views

Why is E°(cell) not ∆E°cell?

$E^\circ_\mathrm{cell}$ is the EMF of the cell for a reaction with respect to standard hydrogen electrode (SHE). So why don't we represent $E^\circ_\mathrm{cell}$ or $E_\mathrm{cell}$ by $\Delta$ ...
7
votes
2answers
1k views

Nernst equation for a fuel cell when gases are stored separately

I have run some tests with a PEM fuel cell and the voltage we have found was $1.44\ \mathrm{V}$. Given that the standard potential for a fuel cell is $1.229\ \mathrm{V}$ what is causing the difference ...
1
vote
1answer
104 views

Calculating the biological standard potential

I have an electrochemical cell with following overall reaction: $$\ce{5 Sn^4+ + 2 Mn^2+ + 8 H2O <=> 5 Sn^2+ + 2 MnO4- + 16 H+}$$ I have defined the half reactions as: $$ \begin{align} \ce{Sn^...
0
votes
1answer
74 views

What is the state of aggregation of iodine formed during electrolysis of molten nickel(II) iodide? [closed]

Assume the electrolysis of molten $\ce{NiI2(l)}$ (inert electrodes) in a cell. The cell with a heating element is in the room; the room is at $\pu{25 °C}$ and $\pu{101.3 kPa}.$ The half-reaction for ...
-1
votes
2answers
60 views

What are possible anode materials for copper(II) sulfate electrolysis?

I'm a student doing a research paper about copper sulfate electrolysis with an experiment by varying anode material, and aside from Pb and graphite (and pure Ti which I think wouldn't work without ...
3
votes
0answers
29 views

Problem interpreting CV diagram in a paper

I am an undergraduate materials science student. I am currently preparing to conduct some research over the summer on alkaline electrolyte membrane fuel cells and have been reading some papers to get ...
3
votes
1answer
205 views

Why does magnesium deposit during electrolysis of a molten mixture of MgI2 and AlBr3?

During the electrolysis of mixed salts, I read, and was taught, that the cation with a higher ionization energy would deposit at the cathode. I was also told that you cannot use the standard electrode ...

1
2 3 4 5
28