More weird stuff with electrolysis

[xeluc]

So I have a 9 Volt DC power supply. I connected Copper to both the Cathode and Anode. There was CuCl2 disolved in the water. Something wierd is happening. The Anode is disolving as you'd expect, But the Cathode has a Gooey Blue precipitate coming form it. My only guess is Copper Hydroxide, but wouldn't that be forming on the Anode since OH is negative? Also there is a black precipitate forming on the Cathode, but that may be form water impurities. Also, why isnt the Cathode being plated with Copper? Everyone can get Copper Plating except me Also, there was a white precipitate omn the Anode, nowhere near as much as the blue stuff though.

[jsatan]

It best to copper plate in copper sulphate.

I think the soln has to be full of the ions you want to plate with, o it will fill the soln, think it as a bettery.

Yeah you will get the blue stuff which will turn brown/red after a while.

if you have the eletrode slightly under this stuff it will stay blue.

 

I'v got a thread where i did this but added some phos acid then sodium carbonate, very very nice cyan, a must see,

[woelen]

So I have a 9 Volt DC power supply. I connected Copper to both the Cathode and Anode. There was CuCl2 disolved in the water. Something wierd is happening. The Anode is disolving as you'd expect, But the Cathode has a Gooey Blue precipitate coming form it. My only guess is Copper Hydroxide, but wouldn't that be forming on the Anode since OH is negative? Also there is a black precipitate forming on the Cathode, but that may be form water impurities. Also, why isnt the Cathode being plated with Copper? Everyone can get Copper Plating except me Also, there was a white precipitate omn the Anode, nowhere near as much as the blue stuff though.

The blue precipitate at the cathode can be explained easily. At the cathode, the following reaction occurs:

 

2H2O + 2e ---> 2OH(-) + H2

 

The 2e is coming from the cathode, delivered by the power supply. The hydroxide ions form a precipitate Cu(OH)2 with copper ions, already present in solution.

 

You use a very high voltage. If you lower the voltage, then I certainly expect less Cu(OH)2 to be formed and more Cu-metal.

 

Another thing is that it indeed is not very good to use CuCl2. It is much better to use CuSO4. CuCl2 forms many complex ions in solution, such as CuCl4(2-) and other less-chlorinated complex species (these complex ions make a solution of CuCl2 appear green instead of blue). These complex ions also makes things more difficult.

[xeluc]

Thanks alot. Your explanation makes perfect sense. I jsut figured teh OH- wouldnt react till it reached the anode. I had it stuck in my head that it reacted with the metal anode, but it reacts with the Ions in the solution, which is obvious, but I'm really relativly new to this. I AM learning so much though. Also, nw I have all this Copper Hydroxide. Is this worth anything to a Chemist? I made these chemicals myself and would like to not waste them if possible.

[woelen]

Thanks alot. Your explanation makes perfect sense. I jsut figured teh OH- wouldnt react till it reached the anode. I had it stuck in my head that it reacted with the metal anode, but it reacts with the Ions in the solution, which is obvious, but I'm really relativly new to this. I AM learning so much though. Also, nw I have all this Copper Hydroxide. Is this worth anything to a Chemist? I made these chemicals myself and would like to not waste them if possible.

Copper hyroxide in fact is quite interesting stuff. If you have tartaric acid (you can buy that at every drugstore), then you can make Fehlings reagent, which is very nice for making red copper (I) oxide or even plating thin solid layers of copper (I) oxide.

 

You can also make the tetrammine complex with copper (II) hydroxide. Add an excess amount of ammonia to a suspension of Cu(OH)2. You'll see that it dissolves and that you get a really beautiful deep blue color. If you also have sulphuric acid (dilute is OK), then you can make the solid salt Cu(NH3)4SO4.H2O.

 

If you have dilute sulphuric acid, then you can make copper sulfate crystals. These are very neat, bright blue. Add dilute sulphuric acid to copper hydroxide, until all of it has just dissolved and then boil away most of the water.

 

Do not try this with nitric acid though. With nitric acid you get Cu(NH3)4(NO3)2, which is very explosive and having a gram or so of this may be enough to blow off your fingers!

[jsatan]

I was reading on the net that copper (I) chloride (ele of salt anc opper eltrodes) will not yeild copper (I) hydroxide. But will make copper (I) oxide, thats why it turns red-ish after a few mins.

But it is a good way to get copper(I) oxide, I've not tried getting this out of the soln, but I will in a few days,

[jsatan]

Now my head is messed up, I've reas that if you have sodium hydroxide with copper chloride then you will get copper hydroxide and sodium chloride.

But then I've read that copper hydroxide will not form, but with water change into copper oxide.

Any ideas anyone?

[YT2095]

and 9 Volts is a BIT MUCH dont`cha think!?

 

try about 2 volts, see how that goes

[xeluc]

Well. I was using a DC Power supply that was originally for a Sega Gamegear. Yes, Old School I know. I would very much like to build a variable power supply. I've yet to make extensive plans. Or buy one, which ever is cheaper. I have a feeling building on is cheaper? Could you point me in the right direction for this?

 

@JSatan... Yeah I have added NaOH to a solution of CuCl2. The greenish solution turned a beautiful dark blue, which lightened after decanting and adding fresh water a few times to get rid of excess NaOH. From MY experience. NaCl witch Copper electrodes yeilds CuO. CuCl2 and copper electrodes yeilds Cu(OH)2.

[YT2095]

you`ll need a suitable transformer, then a fullwave bridge rectifier, a reservior capacitor, say 50v @ 2200uf (depending on the transformer output). and the regulator chip itself, I`de reccomend something like the LM317T.

oh and you`ll need a variable resistor to set the output voltage.

DO not use another reservior After this regulator though.

that basicly is all you`ll need, they go from about a volt up to 36volts

 

here, this`ll help a little: http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm

[xeluc]

thanks a bunch