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Topic: Copper, Salt, and Water Electrolysis?  (Read 7887 times)

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Offline Gelid

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Copper, Salt, and Water Electrolysis?
« on: August 08, 2011, 05:52:12 AM »
So earlier, like a foolhardy almost-9th grader, I decided to experiment with electrolysis. Because I didn't have any actual tools, I cut off the head of an AC adapter and separated and stripped the wires (which were copper), so I could get an electric current (Just a thought here, but would the AC current be separated into a positive(+) and negative(-) charge through the adapter?). I filled a small plastic measuring cup with water and mixed in a lot of NaCl, because I wasn't interested in a simple Hydrogen-Oxygen separation. I knew the risks of breathing in Chlorine, so I kept the experiment very small. When I plugged in the cord and touched the wires to test them (they sparked), I put them both in the water. Both of the wires became black, as though the copper became charred, and started dissolving into a green-blue liquid into the water. I didn't know what to expect, and the green color, I knew was characteristic of chloride, which spooked me a little.

A little research online, held that an H20-NaCl mixture, when electrolyzed, would provide Sodium hydroxide, and 2 chloride atoms. So, I'm assuming, the copper (Cu) wire, reacted with the chloride (Cl) to form CuCl2. Anyone know if I'm correct? Also, just a side note, I know that it's not electrolysis without a direct current, and I was using an alternating current, so I'm not sure if the wires were separated by the adapter, and if not, would the chemical reaction not have occurred / not be the same? Thanks.

Offline Hunter2

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Re: Copper, Salt, and Water Electrolysis?
« Reply #1 on: August 08, 2011, 08:00:47 AM »
Alterning current will not create an electrolysis. The frequency is 50 or 60 Hz = 1/s. The solution gets only hot slowly.

Offline Gelid

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Re: Copper, Salt, and Water Electrolysis?
« Reply #2 on: August 08, 2011, 08:15:04 AM »
Hmm... Then the AC adapter must be outputting a positive and negative charge, though I have no way to test this. Perhaps it's just a physical reaction? Thought I doubt it, the reaction started immediately after I put the wire in, no warming was done, and the reaction didn't work if unplugged.

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Re: Copper, Salt, and Water Electrolysis?
« Reply #3 on: August 08, 2011, 08:19:10 AM »
Did you see green colour on one Electrode (Anode). Copper will be dissolved. If you use a carbon (Pencil) or the middle of an Babycell battery, you would get chlorine. You can smell it.

Offline Gelid

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Re: Copper, Salt, and Water Electrolysis?
« Reply #4 on: August 08, 2011, 09:32:12 AM »
I'm not really sure. One wire dissolved, while the other seemed to do it less quickly, but it was more of a black liquid, and might not have been the green one that the (I'm assuming now is the anode) had.

Offline fledarmus

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Re: Copper, Salt, and Water Electrolysis?
« Reply #5 on: August 08, 2011, 04:53:29 PM »
In 120V AC, one wire would be a ground wire and the other would alternate from + to - at 60 times/second.

Offline vmelkon

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Re: Copper, Salt, and Water Electrolysis?
« Reply #6 on: August 14, 2011, 01:43:10 PM »
In 120V AC, one wire would be a ground wire and the other would alternate from + to - at 60 times/second.

There are 3 wires :)

Offline Borek

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Re: Copper, Salt, and Water Electrolysis?
« Reply #7 on: August 14, 2011, 03:39:00 PM »
In 120V AC, one wire would be a ground wire and the other would alternate from + to - at 60 times/second.

There are 3 wires :)

Depends. Basically two are enough, third is for added safety.
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Offline fledarmus

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Re: Copper, Salt, and Water Electrolysis?
« Reply #8 on: August 15, 2011, 08:22:12 AM »
Yes to what Borek said. In a three wire system, the third wire does not actually go to or from the power plant. It is a ground wire, and is attached to a copper rod driven into the ground outside the house. It is set up to ground any parts of any equipment that should not be charged.

From Gelid's original description, however, he is only using a two-wire system.

I am a little curious about the "AC adapter" part - do you mean an AC adapter for battery operated device like a computer? And when you say you cut off the head, did you mean just the bayonet plug, or did you mean the adapter box?  If the adapter is still in place, you should have DC current in the wires beyond the adapter.


Offline osmiridium

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Re: Copper, Salt, and Water Electrolysis?
« Reply #9 on: February 04, 2012, 10:06:55 PM »
I had the same experiance. Was your CuCl2 precipitate light blue? Here is the reaction I think happened: 2NaCl + Cu  + 2H2O = CuCl2 + 2HNaO +2H. Some eroded copper appeared at the bottom of the beaker. Also, is CuCl2 soluble in room-temperature water?

Offline vmelkon

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Re: Copper, Salt, and Water Electrolysis?
« Reply #10 on: February 06, 2012, 11:18:15 AM »
I had the same experiance. Was your CuCl2 precipitate light blue? Here is the reaction I think happened: 2NaCl + Cu  + 2H2O = CuCl2 + 2HNaO +2H. Some eroded copper appeared at the bottom of the beaker. Also, is CuCl2 soluble in room-temperature water?


Yes, CuCl2 is soluble. BTW, you can get such information from wikipedia.
The blue precipitate is most likely Cu(OH)2.

Also, normally, people don't write HNaO. Write NaOH.
Also, you won't have NaOH and CuCl2 in the same solution. You'll have Cu(OH)2 blue precipitate and NaCl that will stay in solution.

Also, there won't be 2H. Hydrogen form H2 molecules.

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