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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What ionic compound has the lowest boiling point?
Defining a molecule as "ionic" when it has a net electronegativity difference greater than 1.7 on Pauling's scale, which ionic compound has the lowest boiling point? And when it evaporates, ...
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Can ions dissolved in a solution be separated by a magnetic field?
When an ionic compound is dissolved in a polar solvent (eg. salt dissolving in water), the ions disassociate and float freely in the liquid. An electric current flowing through the solution can then &...
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Interpretation of non-spontaneous Gibbs free energy
Good day guys,
I was reading some books on physical thermodynamics, they explain that for system undergoing a chemical reaction whose $\Delta G < 0$ indicating that the reaction can then provide us ...
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How do I calculate the electrical resistance for a sodium chloride solution? [closed]
Im doing a paper on how the concentration of sodium chloride in water affects the electrical resistivity of the solution. My teacher told me that I may not be able to use $R = V/I$ for this as sodium ...
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Measurement of dipole electric field generated by a polar molecule
I'm trying to understand the nature of polar molecules. Have there been experiments where we can say to have actually measured the dipole electric field generated by a polar molecule such as hydrogen ...
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Why sodium ion is able to atract negative charges? [closed]
Why is the sodium ion able to attract negative charges? even though it has 1 excess proton, its electrosphere is further away than the nucleus, wouldn't it be possible to counterbalance the effect of ...
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Why chemical energy is doing the work on the electrons to move them from cathode to anode and not some kind of force?
We say that in an electrolytic cell the redox reactions occuring on the electrodes are exothermic and that chemical energy does work on electrons to move them from cathode to anode and this work done ...
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Do chargeable batteries break the third law of newton? [closed]
When you charge a lithium battery for instance the electron momentum that coming out of the source is stored in the battery. The problem is that the direction of the electron might change when ...
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How does Electron flow in Daniell cells in series look like?
After taking a look at this question: What causes the flow of electrons from anode to cathode in a Daniell cell? i was quite satisfied with answer provided there. One question that remained for me was ...
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Inverse relationship between salinity and conductivity?
I have a salt solution that is saturated at 40C, I measured conductivity and got 440 ms/cm.
I then increased the temp to 50C, add more salt until the solution is saturated again, and measure ...
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Characteristics of melanin based semiconductors built from polydopamine
I am curious to know if the relatively newly developed melanin-based semiconductor materials made with polydopachrome have been able to create films or crystals which visually reflect blue, purple or ...
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Why do my Milwaukee batteries weigh different amounts when charged vs uncharged
We use m12 small sized Milwaukee battery’s and I noticed when I use them I feel like they weigh different when using them sometimes while using them and then I read a article about batteries loosing ...
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Is anode to cathode ion movement due to binding energy and electrostatic field?
I'm trying to understand exactly what chemical and physical effects oxidise the Li atoms and make Li$^+$ ions move from anode to cathode on discharge, and to find numbers in terms of electrode ...
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Which electrode potentials govern Lithium-ion batteries?
I have a very basic question on why Li+ ions move from anode to cathode during discharge of lithium-ion batteries. Others have asked, but the explanations don't give electrode potentials.
what ...
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How the potential difference (PD) between two electrodes changes with electrolyte concentration and distance? [closed]
I set up the following experiment
I keep the black probe fixed to the left electrode. I moved the red probe at different points. I measure a voltage, basically the potential difference (PD) between ...
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Salty water impedance vs. frequency
I was experimenting with measuring the dielectric constant of tap-water and also water with salt added.
The measurement was done by submerging a simple cylinder capacitor into a container with the ...
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What do these lines mean?
I am currently reading about emf and internal resistance and I came across this paragraph. What does this mean?
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If earth water were pure, would the atmosphere still produce lightning?
Like the title says: If Earth’s water were composed of pure H2O molecules, without anything else dissolved in it, would the atmosphere still produce lightning? I remember that distilled water is not a ...
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Galvanic cell - when do we get electric potential?
In the galvanic cell in this image (2nd one with salt bridge): Link
Before putting the copper wire into the solution, do the Zn metal electrons have potential energy with respect to Cu2+'s electric ...
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How do batteries lose capacity in winter?
One problem of electric vehicles is that the battery capacity often shrinks under low temperatures. Some batteries can lose as much as 50% of capacity in winter.
What I don’t quite understand is how ...
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Why can you electrolyze liquids but not solids?
Table salt can be electrolysed in molten form, water in liquid form etc etc but why can it not be electrolysed in solid form? What is the effect of allotrope
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How can I concentrate ions in a very small area?
I am interested in concentrating ions in a very small area, so the ion density of that region is elevated above normal levels.
What is the field of study, or term, that describes what I am talking ...
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Voltage and electron flow in battery
I just had a few confusions with battery voltage and overall how it worked. I tried searching online but the answers were so general they didn't explain "why". To start when we are using up ...
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Can we call rusting of iron a combustion reaction?
In case of rusting of iron the chemical reaction is not fast enough. The oxygen used is not molecular oxygen from the atmosphere but it is the oxygen from water molecule. The reaction is not rapid and ...
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Gibbs-Duhem equation and homogeneous function of mixed Euler order
My question is related to this article by Sorensen and Compan. The usual definition of an homogeneous function of order $\mathcal M$ is by the equation $f(\lambda \mathbf{x}) = \lambda^{\mathcal M} f(\...
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Confusion regarding the definition of electrochemical potential
I am having trouble understanding the concept of the electrochemical potential $\mu$. In my textbook the electrochemical potential is defined as $\mu=\frac{\partial G}{\partial n}$. It seems to me as ...
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How is the potential energy of electrons conserved and increased in series wired batteries? [duplicate]
Suppose we have a simple series circuit with a resistor and 2 batteries of rating v0 - battery 1 and battery 2, connected in series. Battery 1's positive terminal is connected to the circuit and so is ...
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Ni-Cd Battery discharge circuit model [closed]
I am struggling with deriving a set of equations to represent mathematical model of Ni-Cd battery, so would you give me a through explanation and proper textbook/reference articles.
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What is the difference between ionic conductivity and electrical conductivity in an electrolyte?
If we apply an AC current to a conductor it creates an associated alternating magnetic field around it. That's the theory. Additionally, when a current passes through the conductor, there is some ...
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Electrical resistance of sodium chloride solutions with varying temperature
I am doing an experiment where if I try to increase the temperature of the sodium chloride solution I have and then measure resistance, I would expect that the resistance will increase as there are ...
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About a battery's positive terminal
Does the positive terminal of the battery mean that the concentration of electrons is more there. In some places people say that current moves from positive to negative and they call it a convention ...
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What causes water to be non-ohmic?
Its been a while since I posted here about what I have been trying to find out regarding resistance of water at high voltages. I may seem oddly obsessed with this, but it is forming a big part of a ...
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Pressure Drop as a Predictor of Degree of Electrochemical Machining?
I'm trying to get my head around the concept of electrochemical machining and if it would be possible to measure the pressure drop across a pipe as the process is ongoing at a given flow rate to ...
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How water affects the resistance of a material at different voltages?
as I said before in recent science projects I have been studying the effect of water on the electrical resistance of materials that absorb water such as wood and sponge (the reason for the majority of ...
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How electrolytes conducts electricity?
While studying electrochemistry, I came across two key points that I'm unable to understand.
why does DC alone break down the electrolytic liquid
and
b) Why doesn't AC do the same?
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Force on a test charge inside a cell
Considering test charge inside a cell. Let the cell be in an open circuit. I know that a potential difference will develop between the two electrodes of the cell. If I take a test charge and place it ...
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Is tap water an ohmic conductor?
Earlier today, I asked a question regarding why I was getting weird resistance readings and based on responses which I am thankful for concluded it could possibly be the electrolysis, the fact i ...
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What happens to resistance of tap water as voltage is increased?
In recent days I have done a few experiments measuring the current of water as it goes up from 9 volts up to 36 volts, and following Ohms law to convert it to resistance. And I discovered a very ...
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In electrochemical sensing, why do molecules binding cause changes in current?
From my limited understanding in electrochemistry, a set of electrodes are biased at a given potential and when there is a chemical reaction(antibody-antigen binding for example), a subsequent change ...
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Does current flow inside a battery?
When connected in a circuit, does current flow inside a battery. If yes, in which direction?
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What causes the potential difference in a half-cell?
This question pertains to the subject of electrochemistry --specifically a half-cell and not a full galvanic cell.
From what I understand, a half-cell has a potential of its own. This is voltage is ...
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What is the need for reference electrode?
An absolute electric potential of a point is simply not defined. Only the difference between two points is defined and can be measured,so we are forced to take a reference point's potential. Electrode ...
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Maxwell relation for battery undergoing reaction
I am trying to solve Reif Problem 5.16, and seem to continue to run into a barrier. I here give the problem and solution from the solution manual, as well as my work. This is not a homework question. ...
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What causes the flow of electrons from anode to cathode in a Daniell cell?
In a standard galvanic cell, I understand that electrons flow from the anode to the cathode. For example, in a Daniell cell, electrons flow from the Zn anode to the Cu cathode. Before the two half-...
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Electrolysis of a solution of $\rm Ni(NO_3)_2$
This is a problem given in my textbook
A current of $3.7 amp$ is passed for 6 hours between inert electrodes in 0.5 litres of 2M solution of $\rm Ni(NO_3)_2$. What will be molarity of the solution ...
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What causes the electric field in a Daniell Cell?
I would like to know what causes the e-field in a Daniell cell.
From a chemistry point of view, I do understand that this is initiated by a redox reaction in which Gibbs free energy is decreased. The ...
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Why does electrolytic conductance increase with dilution?
We are only talking about strong electrolytes.
According to my book, conductance increases slightly due to dilution.
Explanation given by my book:
On the one hand, in a dilute solution, the number of ...
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What is the cross-section area of an electrode when measuring electrolytic conductivity?
If we have two flat plates,
then the area is understood easily. However, if our two electrodes are like this:
then will we take the area of $S_1$ or $S_2$?
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Is the positive terminal of a Daniell cell positively charged electrostatically?
Suppose, the circuit is open.
I understood from @Dale's answer that the negative terminal of the battery is indeed electrostatically negatively charged. Suppose, it can have a charge of $-0.5C$.
...
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What's the highest theoretical energy density in a chemical battery?
Is there a theoretical limit to how energy dense chemical batteries can be? How can one calculate them? And what stops us from reaching those limits?
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