All Questions
Tagged with aqueous-solution electrochemistry
71
questions
4
votes
1
answer
95
views
Why is my Ni or Fe cathode blackening and pores getting blocked during alkaline (6 M KOH) electrolysis?
I am conducting an electrolysis process for hydrogen $(\ce{H2})$ and oxygen $(\ce{O2})$ generation using a $\pu{6 M}$ $\ce{KOH}$ alkaline solution.
During the process, I have observed that my cathode ...
- 41
3
votes
1
answer
55
views
Experiment on pH vs Rate of Electrolysis - what do the results actually say?
My experimental setup looks at using different pH solutions (of $\ce{H2SO4}$ and $\ce{NaOH}$) for electrolysis of water with a Hoffman setup and then measuring the rate of production of gas (note this ...
- 39
13
votes
3
answers
2k
views
Do electrons really hang around the electrode while ions go take a swim?
This answer to this post addresses "what happens if you dip a single zinc electrode into some electrolyte solution." It explains that
However, though the zinc ion can diffuse through the ...
- 22.5k
1
vote
0
answers
43
views
Increasing energy density for flow batteries with water based electrolyte?
Given a flow battery with a water based electrolyte, would it be possible to increase the energy density of battery by precipitating the redox active species from the anolyte and catholyte solutions? ...
4
votes
1
answer
578
views
Possible technique for measuring pH in solutions
I would like to develop a device that measures pH in aqueous solutions. I'm not a chemist, but I have some basic knowledge about electrochemistry. So, I thought I could use two electrodes quite close ...
- 87
0
votes
0
answers
65
views
Can we add specific conductivities at any concentration?
Suppose we have specific conductivities of $\pu{0.1 M}$ $\ce{K+}$ and $\pu{0.1 M}$ $\ce{Cl-}$. Can we add their specific conductivities to get specific conductivity of $\pu{0.1 M}$ $\ce{KCl}$?
- 17
4
votes
1
answer
234
views
How does a silver chloride electrode (Ag/AgCl) convert the potential in aqueous solution to the wire?
I am aware of the redox chemistry that happens at the electrode surface, but I'm not sure how exactly a change in electrical potential in the solution would change the potential in the electrode?
- 41
0
votes
1
answer
50
views
Passing protons through cation-permeable membranes
Protons are attached to a water molecule (making hydronium) in acidic solutions. If a container was split through the middle with a cation-permeable but anion impermeable membrane and, say, HCl was ...
- 69
1
vote
0
answers
49
views
How the optical fibre pH microsensors work?
Just browsed through the chemical sensor products of the company, called PreSens (https://www.presens.de/products/ph/sensors) in order to look for a precise method to measure pH change in a ...
- 59
4
votes
1
answer
366
views
Variation of conductance of saturated aqueous solution with temperature
The following question was asked in JEE Mains 2020:
Let $C_{\ce{NaCl}}$ and $C_{\ce{BaSO4}}$ be the conductances (in S) measured for saturated aqueous solutions of $\ce{NaCl}$ and $\ce{BaSO4}$, ...
- 476
2
votes
0
answers
109
views
Gouy-Chapman model
Recently I have been investigating the problem of a neutral solutions (with equal number of anions and cations) interacting with an infinite surface $z=0$ with electrostatic potential $\phi(z=0)=\...
- 121
3
votes
2
answers
477
views
Why is my battery of galvanic cells not enough to power a lamp rated for a lower voltage than the battery provides?
I made a series of 12 galvanic cells with saltwater as an electrolyte and zinc and copper as electrodes. It produces 8.8 V, but it can't even light a 2.5 V bulb (the bulb can be lit by a 1.5 V source)....
- 49
1
vote
1
answer
86
views
Incompatibility of Helmholtz Double Layer and Redox electrochemistry
In an electric double layer capacitor(EDLC) (or any situation with a Helmholtz double layer) what prevents the ions from being reduced or oxidized like the ions in an electrochemical cell?
If it is ...
-1
votes
2
answers
188
views
Recovery of Urea from aqueous solution [closed]
When adding Urea to water, the reaction is highly endothermic. I was playing with the idea of using that for a Desktop cooling system, but for that, I'd of course have to recover that Urea from the ...
- 155
1
vote
1
answer
168
views
what happens to the electrons in low-voltage conductivity of salt water [closed]
Suppose you take a 100 millivolt voltage source, and connect it using a pair of copper wires to a bath of salt water.
A current will flow through the water. If I'm not getting things completely wrong, ...
- 27
1
vote
0
answers
54
views
How is formula for mean ionic activity derived from its constituent activities?
I spent hours in order to understand the following - but without success:
At many places the mean ionic activity coefficient for the reaction
$$\ldots \rightarrow \nu_A A^{z_A+} + \nu_B B^{z_B-}$$
...
- 133
0
votes
0
answers
80
views
Copper powder from aqueous copper sulfate solution help
I’ve been wanting to make copper powder for some homemade pyrotechnics. When placing an iron object in a copper sulfate solution, copper powder is produced. However, sooner or later, the reaction ...
- 113
2
votes
1
answer
318
views
Relation between standard silver-silver chloride electrode potential and solubility product of silver chloride
I learned that $E^\circ_\ce{Cl^-|Ag,AgCl}, E^\circ_\ce{Ag^+|Ag}$ and $K_\mathrm{sp}$ of $\ce{AgCl}$ are related as
$$\boxed{E^\circ_\ce{Cl^-|Ag,AgCl} = E^\circ_\ce{Ag^+|Ag} + \frac{RT}{F}\ln K_\mathrm{...
- 750
1
vote
1
answer
648
views
Is this true for conductivity of mixture of two solutions equal to the sum of conductivities of each solution?
Suppose $\ce{Na2SO4}$ has a conductivity $\pu{2.6 \times 10^{-4} S cm-1}$ and on mixing $\ce{CaSO4}$ to saturation, the conductivity becomes $\pu{7.0 \times 10^{-4} S cm-1}$.
So, Is the conductivity ...
- 111
2
votes
1
answer
190
views
Effect of side reactions on galvanic cell using iron rod as anode and sodium chloride as salt bridge
We just made a galvanic cell on a chemistry lesson using iron, iron sulfate , copper and copper sulfate.
We used a sponge soaked in $\ce{NaCl}$ solution as the salt bridge. The issue is that we ...
2
votes
1
answer
338
views
More ions form pairs when concentration of acid increases, does that decrease the speed of reaction?
Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of ...
- 21
2
votes
1
answer
46
views
Would ionic conduction be halted by shielding at the electrodes?
I've done this experiment myself and seen it front of my eyes. Set up a basic circuit with a battery, an LED, and connect the circuit with a salt-water solution and copper wire. The LED lights up.
If ...
- 309
0
votes
1
answer
466
views
How does strong acids conduct electricity in water?
How do strong acids conduct electricity in water?
I have just studied ionization of water and I'm confused about some points.
First: I know that water ionizes in a very small amount ($10^{-14}$) so ...
- 29
-2
votes
1
answer
775
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 ...
- 113
1
vote
1
answer
90
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 ...
- 183
3
votes
2
answers
844
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+(...
- 39
1
vote
1
answer
769
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:
$$
\begin{align}
\ce{Sn^...
- 29
2
votes
0
answers
408
views
Effect of charge density on electrolysis of dilute sulphuric acid
I am told that if electrolysis of dilute sulfuric acid is performed under high charge density, then the following reaction takes place at anode instead of evolving oxygen:
$$\ce{2 HSO4- -> H2S2O8 +...
- 363
0
votes
1
answer
115
views
Solution for Electroplating Selenium?
I need to electroplate selenium onto a conductive metal (for an experiment). The end goal is a thin film of pure, elemental selenium. Unfortunately I can't find anything on the internet: Ideally, I'd ...
- 9
2
votes
0
answers
150
views
Competing half reactions in electrolysis of aqueous solution of sodium hydroxide
If you run a direct current using pure nickel electrodes through a solution of NaOH in distilled water, you will separate the water into hydrogen and oxygen.
Are there any other reactions that could ...
- 177