Questions tagged [electrochemistry]

Electrochemistry is the branch of physical chemistry that studies the relationship between electricity, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electricity considered an outcome of a particular chemical change or vice versa. These reactions involve electric charges moving between electrodes and an electrolyte (or ionic species in a solution).

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Why doesn't a chemical reaction occur with the movement of electrons in the context of electricity?

In school it is generally taught that the movement of electrons between two atoms causes a chemical reaction. However, when it comes to electricity why doesn't a chemical reaction occur with the ...
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Emf, terminal voltage, lost volt & internal resistance

When we insert neutral copper and zinc electrode in a battery containing $H_2SO_4$ the acid splits up.The hydrogen ions move towards the copper plate and the sulphate ions move towards the zinc plate....
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Do people work on improving battery efficiency by increasing entropy difference?

I have been reading a Daniel Schroeder's book called "An introduction to Thermal physics", and after having completed first couple of paragraphs of "Free energy as available work" (...
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64 views

Can electricity pass through a flat battery? [closed]

Let’s say there are 4 batteries in series in a circuit connected to a bulb. One of the battery is flat. Can the bulb still light up? I’m so confused now.
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Formulating electric potential in a battery

The electric potential $V$ around an electric field $E$ can be described with this formula: $$V=Ed$$ where $d$ is the distance from an electric charge. Now, if I recall it correctly from ...
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1answer
29 views

Does potassium ions have a longer range attraction than sodium ions or hydrogen ions?

Electronegativity decreases with period in in the periodic table. The explanation for that is because the distance to the nucleus decreases with each orbital shell of electrons, if I got that right. ...
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4answers
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Why exactly do we feel a shock when we place our hand into a conducting solution?

I have a very naive question. Suppose you have pure water in a flask, and you place two ends of a copper wire (which are connected to a battery) into the water. If you were to place your hand into the ...
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45 views

Confusion between positive and negative terminals of a battery

I am confused that whether the positive terminal in physics refers just to a higher potential or a positive charge. This also comes from the fact that anode and cathode are differently charged in ...
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1answer
44 views

Lemon Battery Voltage Increase

Suppose I have 2 lemons each with a zinc nail and a penny for electrodes and I wire them up in series so that Nail-A passes through a load and connects to Penny-B and Nail-B connects to Penny-A. I ...
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22 views

What is the non-electrostatic force exerted on an electron in the given scenario?

My teacher was explaining emf to me and he was using an example of a simple electrolytic cell. In this example the two electrodes had been placed in the same solution and had been connected by a wire. ...
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16 views

The voltage across an electrochemical cell

Suppose I have a galvanic cell, like the one below In the other resources I checked (such as LibreTexts, Chem Pages, and Khan Academy), it is mentioned that the voltage across such a cell is ...
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What exactly happens when $\rm NaCl$ water conducts electricity? [closed]

Assume a DC power source with $2$ electrodes made of Fe. We dip those $2$ electrodes into table salt water. What happens exactly? Will $H^+$ and $Na^+$ migrate to the negative electrode by ...
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55 views

Will earthing an aluminium boat reduce the rate of hull corrosion?

First question here as I am having trouble getting a decent answer anywhere else, such as boat service workshops etc. I wish to reduce corrosion on an aluminium hull over its lifetime, hence this ...
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1answer
35 views

Why does a battery voltage depend on its state of charge?

I know that measuring the open-circuit voltage gives a good indication of the state of charge of a battery, both for rechargeables and single-use. But why is this so? As far as I can see the voltage ...
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69 views

What is the strength of current in electrolytes?

if a battery is connected to an electrolytic cell, what is the magnitude of the current in the electrolyte compared to the the magnitude of the current in the wire? This doesn't make sense to me ...
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15 views

In a Lithium Ion battery (during discharge) positive Li Ions flow to the +3.8 volt cathode. Where do they get the energy to climb that 3.8 V hill? [duplicate]

These positive $\text{Li}$ ions are flowing up hill to the cathode during discharge so where is the energy coming from that allows them to get over the hill?
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97 views

Does the EMF negate when a cell is being charged?

A defining equation of electrochemical cells is that the EMF, $\mathcal{E} = E_{red/cat} - E_{an/ox}$, equals the electric potential of the cathode minus that of the anode. This means that if a cell ...
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40 views

Nernst equation and very diluted solutions

Nernst's equation does not predict the correct potentials of very diluted solutions. Intuitively, I would say that in such conditions there are not enough reactive particles at the surfaces of the ...
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1answer
35 views

Does electromagnetic radiation cause auto-ionization of water?

The auto-ionization of water into $\text H^+$ and $\text{OH}^-$ is often described as occurring spontaneously, that at any given time a tiny portion of the water will be split into its cation and ...
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What is the literature value for ${\rm CuSO}_4$ electrolyte concentration required for Zinc - Copper electroplating?

I am currently working on a lab report where I am exploring factors that affect the rate of electroplating - currently looking at electrolyte concentration. I am electroplating copper with zinc. ...
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Microscopic interpretation of constant voltage from Battery

I don't know if this is the right place to ask(Maybe it's more related to chemistry), but this has been troubling me for some while. Consider you have a chemical cell. Then the reason for the ...
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86 views

Why do batteries need a loop to discharge?

I'm an electrical engineer who has been taught transistors and silison and solid state theory and all that. But when I apply the theory to batteries and cathodic protection, my understanding seems to ...
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3answers
88 views

Why does the internal resistance of a rechargeable battery depend upon whether it's charged or discharged?

The following text is from Concepts of Physics by Dr. H.C.Verma, chapter 32, "Electric Current in Conductors", page 199, 19: The internal resistance of an accumulator battery of emf $6\ \mathrm V$ ...
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Origin of terms in the Nernst-Planck equation

We know the Nernst Planck equation is $$ \frac{\partial c}{\partial t} = - \nabla \cdot J \quad | \quad J = -\left[ D \nabla c - u c + \frac{Dze}{k_\mathrm{B} T}c\left(\nabla \phi+\frac{\partial \...
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21 views

Tunneling of electrons in a metal junction

If a metal of two different chemical potential are placed together, thermodynamics tells us that electron will flow from higher to lower chemical potential to reach an equilibrium. But it is not ...
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66 views

Work function for two metals in equilibrium

On studying different books and journals of electrochemistry I found that many confusions have been made in defining the term work function. A general definition of work function is that it the ...
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24 views

Parallel plate electrodes dipped into a dielectric fluid [duplicate]

I am trying to solve the problem 50. in a MIT Problem set. The problem is as the picture dipicts. What I am confused is that why the fluid can be pulled up. What kind of force acts on the fluid except ...
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19 views

Frequency Dependent Debye Screening

I'm interested in looking at electrolyte solutions and effects of microwave electric fields in them. One important property is the impact of Debye screening, which occurs in many solid state problems ...
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20 views

Scaling analysis of the Nernst Planck equation for a battery

The Nernst Planck equation states $$ \frac{\partial c}{\partial t} = - \nabla \cdot J \quad | \quad J = -\left[ D \nabla c - u c + \frac{Dze}{k_\mathrm{B} T}c\left(\nabla \phi+\frac{\partial \mathbf ...
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1answer
143 views

Which color in emission spectrum do we really see?

For example, potassium has this emission spectrum according to google image It is typical (and kinda necessary) for atoms to have multiple emission lines, so what determines which color we actually ...
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What power density could a cell phone battery achieve, and how? [closed]

Current cell phones have batteries reaching about 3500mAh capacity, and I believe Lithium-Ion technology is rated at around 100Wh/kg (?) Is there a theoretical limit to how much power could be stored ...
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Collision Frequency in Liquids

I’m trying to quantify the current produced due to electrolysis of an electrolytic solution. What physical model can I use to determine the mean velocity of each ion species in my solution, taking ...
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1answer
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What defines a material is an anode or a cathode?

How to know if a material is an anode or cathode? and if i connect an anode and a cathode will it be a diode? Like the pensil razor diode, if it worked not because of that, how does it work?
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32 views

Velocity of particles in electrolysis

In an electrolysis (H20) water is split up and the protons start to move towards the anode. So one would be able to calculate the acceleration of the proton from the electric field in that area. ...
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What is the interaction between dissolved ions of opposite valence in a solution at rest?

NaCl is dissolved in water. Ions sodium and chloride are sufficiently free from each other so that they may occupy different regions of the solution after an active transport process through a ...
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81 views

In the Volta potential or Nernst potential equations, where does the logarithm come from?

In both Volta potential and Nernst potential equations, besides some constants, temperature and valence parameters, the potential is a function of the logarithm of the ratio of two densities (or ...
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18 views

$H_2O$ dissociation by ionization in a discharge tube

As a casual amateur scientist, I wonder if it is efficient to electrolyse water in a discharge tube. I imagine that there would be 4 electrodes arranged perpendicularly. the first set of electrodes ...
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68 views

Is Lithium Plating possible at the cathode, too?

When talking about the Failure Mode 'Lithium Plating' in Lithium Ion batteries, in literature it is just described at the anode and I could not find answers to why it is not happening at the cathode, ...
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1answer
92 views

On direction of electric field in a battery

I know that the electric field points from positive to negative potential in a circuit but it is opposite inside a battery for the purpose of continuity of electron flow and electric field....but why ...
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10 views

Calculate for a Shell charge for the Interatomic Potential (aka Force Field)

I am trying to calculate shell charge of an atom in order to get spring constant for the IP calculation. I used the DFT method to calculate the dipole moment of an atom and polarisability of the atom ...
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Is equilibrium potential relative?

If you have a half cell reaction, let's say: $Zn$ electrode and ($SO_4^{2-}$ and $Zn^{2+}$) solution The solution will get more and more postive and the electrode more and more negative until $\...
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Difference between Capacitor and a battery [duplicate]

Capacitor stores electric charge and battery also stores electric charge. SO whats the difference between them?
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159 views

Electrolyte and internal resistance

If you have a Daniell cell(zinc / copper), excess charges will build up on the electrodes making the open circuit voltage until the reactions halt. Now in normal situation when you connect their ...
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1answer
100 views

Is Ohm's law valid for water?

I have $E$ (electric field intensity) in water. I want to find $J$ (current density). I don’t know if Ohm's law ($J=\sigma E$) is valid for water. If it is not valid, how do I may find out $J$?
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36 views

How cell drives electrons to flow in a metal wire?

This was my approach using some facts I'd known- At cathode and anode of a cell reactions take place making positive terminal positively charged and negative terminal negatively charged I.e. there are ...
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39 views

Concentric cylinder cell constant

For a concentric cylinder cell (with liquid dielectric), mathematically the equation for the cell constant will always yield a lower value than for the parallel plate case for the same volume of fluid....
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96 views

How to calculate the chemical potential for a 2D lattice gas with excluded volume?

The chemical potential of a 2D lattice gas is given by $$\mu = k_\mathrm{B}T\ln\left(\frac{c}{(1-c)q}\right),\tag{1}$$ where $c$ is the concentration of particles on the lattice, $T$ is the ...
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241 views

Kinetic energy and current

When a battery is connected to a resistance circuit, we know that it loses energy because heat is emitted as a result of the collisions between the electrons and stuff, but my question is, is the ...
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321 views

Relationship between concentration and resistance of aqueous solutions

I'm a senior physics/chemistry student working on a practical assignment where I am trying to identify the resistance of CuSO4 in solution (distilled water). I have recorded my data and determined it ...
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148 views

Assumptions for Nernst Equation

While I am familiar with some of the conditions for the Nernst Equation, for example: 1) "The membrane is only permeable to one ion even if there are several other ions in the system" there is an ...