Aluminum mystery -- Questions about elecrolysis in water

  • #1
BenDover
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TL;DR Summary
Aluninum seems to work and not work as electrodes in the electrolysis of sodium sulfate
Hello, human people's.

I noticed a strange phenomenon while playing electrochemistry.
- i used 2 strips of aluminum foil as electrodes in sodium sulfate solution, 1 for positive terminal and other for negative. Applied 5 volts, essentially zero current flew.

- i used 1 strip aluminum for negative and 1 copper wire for positive, same solution, small current flowed, milliamps worth.

- i flipped/swapped/switched terminals and had positive on aluminum anf negative on copper, zip/zilch,nada, no current flowad.

Seems strange, aluminum shouldn't be taking place in reaction, just serving a serface area for a reaction to occur. Hydrogen is produced on the aluminum which makes it obvious current can flow through the aluminum and the surface of aluminum can be used for reactions to occur, but when both electrodes are aluminum, no reactions take place on surface and when aluminum is on positive side and copper is on negative side, no raeations take place, but swap copper and aluminum and hydrogen is produced on aluminum side and copper side oxidizes and allows a surface for oxygen reactions to occur.

So it seems aluminum conducts electricity just fine but something is not allowing oxygen to be produced on the aluminum surface. It doesn't make sense.

Why is the surface of aluminum able to be used to produce hydrogen but not oxygen?

P.s. usually i notice metals get "clean" on hydrogen side, but for some reason aluminum darkens.

Al is so strange. I have a hard time believing any "it has an oxide layer" ideas because doesn't every metal? Doesnt the piece of aluminum hooked to the negative terminal producing hydrogen have a oxide layer?

Any help understanding Al is appreciated peeps

Thanks for helping
 

Answers and Replies

  • #3
BenDover
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Could you tell me what you think is helpful to answer my question in those articles? I can't read your mind by reading those articles, brah

Perhaps some insight from this article:

https://app.aws.org/forum/topic_show.pl?tid=22168

and

https://www.researchgate.net/post/Why_aluminium_is_used_as_current_collector_at_cathode_side_and_copper_at_anode_side_in_Li_ion_battery
 
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  • #4
berkeman
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Could you tell me what you think is helpful to answer my question in those articles?
Welcome to PF.

Well, you addressed us as "human people's [sic]", and that clearly does not apply to all of us (note his avatar). I don't blame him for being a little ticked off...

Plus, the article he linked to does mention how the oxidation of Al hinders current flow...

Anyway, why don't you just use standard electrode materials for your electrolysis experiments?

https://en.wikipedia.org/wiki/Electrolysis
 
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  • #5
BenDover
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If oxidation hinders current flow, why does current flow and show so by producing hydrogen gas yo?


Welcome to PF.

Well, you addressed us as "human people's [sic]", and that clearly does not apply to all of us (note his avatar). I don't blame him for being a little ticked off...

Plus, the article he linked to does mention how the oxidation of Al hinders current flow...

Anyway, why don't you just use standard electrode materials for your electrolysis experiments?

https://en.wikipedia.org/wiki/Electrolysis
 
  • #6
berkeman
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If oxidation hinders current flow, why does current flow and show so by producing hydrogen gas yo?
Hey, yo, I don't no, brah. :smile:

Maybe linked to polarity? Oxidation only forms in one polarity direction, no?

Anyway, Al foil is a poor approximation of an aluminum slab, IMO. It often has coatings in cooking rolls, in my experience.

Do you want a good hydrolysis setup, or are you more interested in understanding the chemistry? (or both?)
 
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  • #7
BenDover
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Idk how you could help me understand anything about chemistry since you don't know why an oxidized piece of aluminum conducts electricity and provides a surface for a reaction to take place on one side of this cell and not the other. And from what i know, copper also has an oxide layer, yet allows oxygen to be produced. So oxide layer seems incorrect for a reason oxygen won't be produced on aluminum surface in this cell. Do you have any educated guesses for why aluminum won't work or are you just a hobby experimenter like i am?

Hey, yo, I don't no, brah. :smile:

Maybe linked to polarity? Oxidation only forms in one polarity direction, no?

Anyway, Al foil is a poor approximation of an aluminum slab, IMO. It often has coatings in cooking rolls, in my experience.

Do you want a good hydrolysis setup, or are you more interested in understanding the chemistry? (or both?)
 
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  • #8
berkeman
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Idk how you could help me understand anything about chemistry since you don't know why an oxidized piece of aluminum conducts electricity and provides a surface for a reaction to take place on one side of this cell and not the other. And from what i know, copper also has an oxide layer, yet allows oxygen to be produced. So oxide layer seems incorrect for a reason oxygen won't be produced on aluminum surface in this cell. Do you have any educated guesses for why aluminum won't work or are you just a hobby experimenter like i am?
Well, it's pretty hard to take your posts here seriously as a newbie when you use language like a 10 year old. Can you post links to the reading you've been doing about electrolysis and the best materials to use?
 
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  • #9
BenDover
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I guess that means you either can't or won't answer the questions and possibly have some personal issues you try to make yourself feel better about by acting like you have shown me. Thanks anyways. Hopefully someone who doesn't hate themselves will answer the questions i asked. Hope you feel better soon. Toodles

Well, it's pretty hard to take your posts here seriously as a newbie when you use language like a 10 year old. Can you post links to the reading you've been doing about electrolysis and the best materials to use?
 
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  • #10
berkeman
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I guess that means you either can't or won't answer the questions and possibly have some personal issues you try to make yourself feel better about by acting like you have shown me. Thanks anyways. Hopefully someone who doesn't hate themselves will answer the questions i asked. Hope you feel better soon. Toodles
Nah, it's just that your first thread start here is substandard, and a bit insulting in your abuse of language and grammar.

This first thread start attempt is closed. Please start a new thread with good links to the reading that you've been doing about how to set up an electrolysis apparatus and what you have read about how the electrode materials affect the apparatus. You can re-post here in the Chemistry forum, or maybe in the DIY forum.
 
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