Questions tagged [electrolysis]

For questions about the chemical concepts of electrolysis.

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What effect do iron impurities in a KOH electrolyte have on alkaline water electrolysis?

I have done some research but can't seem to find a proper answer. If there are iron impurities in a KOH electrolyte used for water electrolysis, what issues does this cause? Especially on the cathode.....
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Is anodizing of mixed metals (aluminium and cooper) possible?

I'd like to blacken my Noctua NH-P1 passive cooler, made from an aluminium fins and copper heatpipes. Since thermal dissipation is key in my build, I thought about anodizing it, instead of spray paint ...
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Electrolysis of water+salt: Which molecules is the product?

I should show the kids how electrolysis could create $\ce{H2}$. We used a drinking glass of water mixed with salt. Then we put an 1.5 volt AA battery in the glass and the electrolysis was visible ...
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If i electrolyse a solution containing salts of various metals, will they deposit in layers?

Imagine i have a solution with multiple different metal ions, having different electronegativity and oxidation states. If i perform electrolysis of this solution, will the different metals deposit in ...
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Kolbe's electrolysis reaction for alkenes' production

I came across a question in which the major product was asked for Kolbe's electrolysis of potassium salt of 2,3-dimethylbutane-1,4-dioic acid. The answer was given as trans-(but-2-ene). I couldn't ...
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How can I produce Red Iron oxide with electrolysis

I am producing Iron Oxide with the intention of using it for pigmentation. My attempts so far have been to use electrolysis. My first attempt I used Borax as an electrolyte and a 12 volt adapter with ...
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What happens to undissolved salt during electrolysis of brine?

Say we have a container of brine with excess NaCl in the anode, and a seperate container with just water at the cathode. Both are connected by a salt bridge. If we perform electrolysis, Sodium ions ...
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When performing electrolysis of brine, are carbon steel electrodes ok? [closed]

Are carbon steel electrodes better? Do they both eventually corrode? Is there any cheap electrode that stays inert indefinitely?
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Why is copper discharged in the electrolysis of copper (II) sulphate solution instead of hydrogen?

In the electrolysis of copper (II) sulphate with graphite electrodes, I am confused why copper ions are discharged and form copper metal at the cathode. As far as I know hydrogen ions have a lower ...
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Do ion-exchange membranes *always* require ions to pass in both directions?

In an answer to this question, it was asserted that: Student always tend to forget that a solution must remain electrically neutral by all means. If you want a certain ion to leave water, you must ...
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What endothermic reactions can be effectively reversed by electrolysis?

Not only newbie, but total layman here; please be patient with me. Given are either two different elements, two different molecules, or one element and one molecule (chemical A and chemical B). A and ...
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Electrolysis when E_cell = 0

I'm a bit confused by the electroplating of Zinc onto Copper, with Zinc (anode) and Copper (cathode) electrodes in a Zn(NO3)2 solution. The reduction reaction is: Zn2+ + 2e- ---> Zn (s) (E_rxn = -0....
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Electrolysis with salt water on steel plates creates horrible black liquid

We are doing an electrolysis experiment using distilled water with sea salt on clean stainless steel plates. A horrible black gunk has formed in the water, very quickly. What is this? I don't ...
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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)=\...
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How are membranes for Polymer electrolyte membrane electrolysis produced?

Polymer electrolyte membrane electrolysis is a process used for creating hydrogen with a thin metal membrane. This membrane is often includes a thin metal sheet of Platinum. My question is, how these ...
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What metals are safe to use as electrodes when doing electrolysis of water (I am trying to produce hydrogen gas)

I am going to be a DC power converter (with fairly high voltage and amps) to turn water into hydrogen (and oxygen) gases. However I have a few questions about the safety of this process. What ...
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Can sodium sulfate be used in the salt bridge?

My book mentions sodium sulfate ($\ce{Na2SO4}$) as an electrolyte that can be used in a salt bridge. I'm asking this question because ChemLibreTexts says that It is also important that the charge ...
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Is H2 gas produced when a mercury electrode is used as cathode in the electrolysis of Brine?

If platinum electrodes are used as electrodes, H2 gas and Cl2 gas are produced at the anode and cathode respectively. However, if a mercury electrode is used as the cathode, an exception is seen. ...
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What will happen if the electrolysis of Brine takes place for a long time?

This is the reaction: $$\ce{2NaCl(aq) + 2H2O(l) -> 2NaOH(aq) + H2(g) + Cl2(g)}$$ If the above reaction goes on for long enough, we will eventually run out of Cl- ions. There will only remain an ...
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Will an electrolyte eventually stop conducting electricity? And if so, gradually over time or suddenly?

I understand that an electrolyte does not conduct electrons, but rather that the positive and negative dissolved ions are attracted by electric charge to the cathode and anode where they receive and ...
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Relationship between cell potential and applied potential in electrolysis

My question is about this problem, and I got the correct answer (which is 495g), but I am confused about the concept behind the correct approach: "Calcium metal is obtained by the direct ...
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Concentration of copper ions in refining of copper metal during electrolysis

When refining copper, would there be a circumstance when the concentration of copper ions in the electrolyte drop? I only know that when refining copper the color of the solution should remain the ...
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Is there a recommended frequency when driving an alkaline water electrolyzer?

We are designing a small electrolyzer (about 1 kW input power) for HHO gas generation. Sadly most of the literature online is bordering on the snake oil… However, it works fine with DC driving. Now ...
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Products formed on the electrolysis of wet HF

We know that, electroysis of water produces $\ce{O2}$ at anode and $\ce{H2}$ at cathode. In a similar way I thought that on electroysis of $\ce{HF}$ it would produce $\ce{F2}$ and $\ce{H2}$ at their ...
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How does concentration of the electrolyte changing over time affect the rate of electrolysis in sodium sulphate solution?

During the electrolysis of sodium sulphate solution, hydrogen is produced at the cathode and oxygen (from the hydroxide ion) is produced at the anode. Then I believe that the rate of electrolysis is ...
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Green colored substances forming during electrolysis [closed]

I saw this but the OP didn't provide further information. My setup is a glass container with the anode and cathode as slim metal pieces and using a 12v charger. The solution was a saturated salt ...
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Why aren't electrolytic cells usually separated?

Galvanic cells need to be separated so that electrons will be forced to move through the external circuit, but I was wondering why electrolytic cells are usually not kept separated but rather as a ...
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Cannizzaro reaction via electrolysis

As cannizzaro reaction reaction is a redox reaction carried by adding base to an aldehyde, is it possible to carry out the reaction using electrolysis where graphite anode and copper cathode is used. ...
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1 answer
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Why do I measure some remaining voltage after disconnecting an electrolyte from a voltage source?

I'm not at all an expert in electrochemistry and want just understand a little what is going on: I have a NaCl solution in water, connected most simply by plain copper conductors. My observation is: ...
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Excess of OH- ions in electrolysis of sodium chloride solution

In the electrolysis of dilute or concentrated sodium chloride solution, at the cathode as hydrogen ions discharge and cause an excess of hydroxide ions, why doesn't the negativity of the cathode repel ...
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6 votes
1 answer
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What is an efficient way to generate CO2 electrochemically?

I would like to build a small carbon dioxide generator for experimental purposes. There are two requirements that are set in stone: It has to be electrochemical. (Easy to switch on/off with ...
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Alumina solubility in cryolite (Hall-Heroult process)

For the Hall-Héroult process, the solubility of alumina in flux seems to be important. But why should I care about the persence of alumina in the bath? I can use feeder to keep the concentration ...
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Why does current flow in an electrolytic cell?

Many explanations of current flow in electrolytic cells will state that electrons flow from the external power source into the cell (via the cathode). But surely this current flow would stop if there ...
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Why does increasing electrolyte concentration increase the rate of electrolysis?

I'm a Chemistry teacher and have students who are performing an experiment to determine the effect of copper ion concentration on the rate of solid copper formation at the cathode in an electrolytic ...
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1 answer
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Usage of AC to measure the conductivity of ionic solutions

there was this statement in my chemistry textbook.... However, for measuring the resistance of an ionic solution we face two problems. Firstly, passing direct current (DC) changes the composition of ...
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Can chloralkali process be used with ocean water to produce sodium hydroxide?

Are there any modern-day Chloralkali plants that create $\ce{NaOH}$ using water from the ocean? I'm trying to understand how modern-day plants that use the Chloralkali process to create $\ce{NaOH}$ (...
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Simultaneous electrolysis on applying a suitable amount of potential difference

This question was asked in the JEE in 2020: $\pu{250 mL}$ of a waste solution obtained from the workshop of a goldsmith contains $\pu{0.1 M}$ $\ce{AgNO3}$ and $\pu{0.1 M}$ $\ce{AuCl}.$ The solution ...
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Zn galvanic cell without electrolyte?

I performed a classical experiment with Zinc-Copper galvanic cell. The zinc electrode was made from pure zinc wire, the copper electrode was made from pure copper wire, the container was a glass ...
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Hydrogen safety during electro-chemical machining

I'm interested in doing some experiments with electro-chemical machining in my shop. The process involves running electricity through an electrolyte (salt water) to break down a metal anode (aluminum/...
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2 answers
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Will electrolysis of molten sodium hypochlorite work [closed]

I have an anhydrous mixture of sodium hypochlorite and sodium chlorate that was obtained by boiling bleach. If I were to melt this mixture and perform electrolysis on it, would sodium metal be ...
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1 answer
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Why does temperature increase rate of electrolysis even though resistivity of electrodes increase?

My experiment is just the electrolysis of iron rust at different temperatures. It consists of a rusted iron cathode and an iron anode in a salt water solution. From my data, there is an approximately ...
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1 vote
1 answer
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Suppressing flammable foam formation in electrolysis

I often use electrolysis to remove rust and other junk off of steel parts. My general setup is: Electrolyte: Sodium bicarbonate + distilled water. Anode: Plain carbon steel Cathode: Carbon steel, ...
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what are the differences between reversible cells and rechargeable cells?

My chemistry textbook says daniel cells are reversible, but not rechargeable. Why is it that all reversible cells are not rechargeable? Are all rechargeable cells reversible? why/why not?
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1 vote
1 answer
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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, ...
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How can one change the color of Iron Oxide by changing the composition or hydration?

How does the color of rust change depending on its makeup and state, or more to the point, how would one put the rust into that state? For example, Wikipedia shows Iron(III) Oxide as being red in the ...
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Hydrochloric acid from diaphragm electrolysis

I have a diaphragm electrolysis cell, which is made up of an outer container containing the cathode and a small terra cotta pot containing the anode. If sodium chloride solution is placed in the outer ...
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Converting dissolved chromates to solids for disposal

I have 4 liters of electrolysis waste that was used to process stainless steel cathodes. About half of it was oxalic acid based and the other half was sodium bicarbonate based (currently stored ...
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What happens in an electrolytic cell when the cations are different from the metal of the anode?

Suppose we have an electrolytic cell with copper(II) sulphate solution as the electrolyte, and lead metal as the electrodes. Will lead ions be discharged from the anode into the solution? What will be ...
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Understanding electrolysis w/ oxalic acid electrolyte, iron electrodes

I've been experimenting with electrolysis for rust removal, electroplating, de-plating, etc. Right now I have a rust removal setup with carbon steel electrodes and a solution of oxalic acid in ...
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Linearity of membrane resistance and contact resistance overvoltages in proton-exchange-membrane-water-elektrolyzer-cells (PEM-WE)

I am questioning why the cell component's resistance to the electrons (contact resistance) and protons (membrane resistance) flow follow the ohmic law. This assumption is made in recent papers on PEM-...
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