Sciencemadness Discussion Board

Making Copper Hydroxide

Random - 30-6-2010 at 13:38

I am thinking about making copper hydroxide. I would use solution of baking soda in water with iron cathode and copper anode. I would try to use small amounts of NaHCO3 as electrolyte because of Copper Carbonate formation. For the battery it could be 9V or few 1.5V batteries. Would I get "almost pure" Copper Hydroxide with this?

mnick12 - 30-6-2010 at 13:57

That would take a long time to make any decent amount of copper hydroxide. Your best bet is to run over to a hardware store and buy some root killer (copper sulfate) and some crystal drain cleaner (lye/sodium hydroxide). Mixing these to chems at low-ish temperature in aqueous solutions will give you copper hydroxide. The only problem you will encounter is filtering off the copper hydroxide, in my experience it tends to be a blob of blue goop which is hard to filter and dry.

Good luck

Random - 30-6-2010 at 15:11

Quote: Originally posted by mnick12  
That would take a long time to make any decent amount of copper hydroxide. Your best bet is to run over to a hardware store and buy some root killer (copper sulfate) and some crystal drain cleaner (lye/sodium hydroxide). Mixing these to chems at low-ish temperature in aqueous solutions will give you copper hydroxide. The only problem you will encounter is filtering off the copper hydroxide, in my experience it tends to be a blob of blue goop which is hard to filter and dry.

Good luck



The problem is that I don't have NaOH and I can't buy it where I live, so I am trying to make it with electrolysis. Thanks for suggestion though, maybe i'll try this in the future :) Cu(OH)2 should be actually gellatinous solid as its stated on wikipedia.

By the way, what is the reaction with electrolysis when using baking soda as electrolyte, copper anode and iron cathode?

[Edited on 30-6-2010 by Random]

mnick12 - 30-6-2010 at 15:36

Im not sure what the reaction is, since I do not really understand electrochemistry that well. But I could try and help you. Copper anode dissolve to give (Cu2+) which combines with OH- to make copper (ll) hydroxide, and hydrogen at the cathode. Thats my best guess. And the baking soda just makes the water more conductive I doubt it actually participates in the reaction very much.
Another thing you may want to use something else for you cathode, because pure iron rusts very easily. Stainless steel would work fine.

You could get decent amounts of copper hydroxide from electrolysis, but not from a 9v battery. An old computer power supply makes a wonderful DC power supply for all your electrolysis needs. Yes copper hydroxide tends to be "gelatin" like , and that is what makes it so hard to filter.

Hamilton - 30-6-2010 at 16:00

use copper for anode and cathode and switch every half a day to maximize conversion speed. if you get your cell temperature to 90 c with the energy from your electrolysi,s copper should corode very fast. try to get 6-7 amp with some insulation

Don't use battery, use a power supply like a computer one. You can approximate that you won't get more copper hydroxide than the size of your battery...(well approximate)

I "eat" up pounds of copper tubing to produce copper salt like acetate. i did some black copper oxide by electrolysis some months ago using a solution of chlorate. Better use hypochlorite for pure black oxide, that's what i learn. For blue hydroxide i think you can take alkali carbonate. i don't plan to see the carbonate moving fron the sodium to the copper anytime soon but the copper will wear.

[Edited on 1-7-2010 by Hamilton]

Random - 30-6-2010 at 23:25

Quote: Originally posted by mnick12  
Im not sure what the reaction is, since I do not really understand electrochemistry that well. But I could try and help you. Copper anode dissolve to give (Cu2+) which combines with OH- to make copper (ll) hydroxide, and hydrogen at the cathode. Thats my best guess. And the baking soda just makes the water more conductive I doubt it actually participates in the reaction very much.
Another thing you may want to use something else for you cathode, because pure iron rusts very easily. Stainless steel would work fine.

You could get decent amounts of copper hydroxide from electrolysis, but not from a 9v battery. An old computer power supply makes a wonderful DC power supply for all your electrolysis needs. Yes copper hydroxide tends to be "gelatin" like , and that is what makes it so hard to filter.



Thanks for this, I'll try to get copper cathode too. I will see about power supply if I'll be able to get one. It's gelatin like, but I would decant it and then dry it in the air (it's almost insoluble in water while NaHCO3 is soluble)

Random - 30-6-2010 at 23:26

Quote: Originally posted by Hamilton  
use copper for anode and cathode and switch every half a day to maximize conversion speed. if you get your cell temperature to 90 c with the energy from your electrolysi,s copper should corode very fast. try to get 6-7 amp with some insulation

Don't use battery, use a power supply like a computer one. You can approximate that you won't get more copper hydroxide than the size of your battery...(well approximate)

I "eat" up pounds of copper tubing to produce copper salt like acetate. i did some black copper oxide by electrolysis some months ago using a solution of chlorate. Better use hypochlorite for pure black oxide, that's what i learn. For blue hydroxide i think you can take alkali carbonate. i don't plan to see the carbonate moving fron the sodium to the copper anytime soon but the copper will wear.

[Edited on 1-7-2010 by Hamilton]


At 90°C it would decompose to CuO, so I need lower temperature (under 80°C). Thanks for suggestions, I will try exchanging cathode and anode.

not_important - 1-7-2010 at 18:09

Any carbonate or bicarbonate use us as an electrolyte is going to end up in the precipitate as basic carbonates. Use a sulfate or chloride instead.

You are likely to get a fair amount of copper plating out, unless you work hard at keeping diffusion of copper ions down so they react with OH- before they have a chance to reach the other electrode.

There are other ways of making Cu(OH)2. Using CuSO4 and slowly adding aqueous ammonia until the solution is nearly colourless works, if you add too much ammonia the liquid will start getting bluer.

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