Need help, copper soln

[jsatan]

Hi,

I did electrolysis on some copper electrodes in a sodium chloride soln.

 

This gave me a nice blue coloured soln/gell at the bottom.

This after time turned red/brown ish.

So from what I know this was happened:

copper chloride + sodium hydroxide ---> copper hydroxide + sodium chloride

 

Then I added some phosphoric acid, this cleared the mixture.

I'm not sure what happened at this point.

 

I think (sue to a clear soln) that this happened:

 

Copper hydroxide + phos acid ----> copper phosphate + water

 

But then this happened:

 

Copper phosphate + sodium chloride ---> copper chloride + sodium phosphate

This soln was crystal clear.

 

I then added some sodium bicarbonate (waited a while).

This turned the soln a very very nice cyan blue.

Mayve this happened:

copper chloride + sodium bicarbonate --->copper carbonate + sodium chloride + co2

(nice color, )

 

So thought I’d try and dry this etc.

I let the cyan blue settle to the bottom of the soln, then sucked out the top soln (water type colour) and then added more water.

I let this stand for a while (30min or so) and the nice cyan turn a dirty greenish colour. it had a very slight red/brown mark on the top.

 

But can any one explain what happened here?

 

Edit, I think im right, the colout of copper carbonate (united nuke's) is the colour of the mixture b4 it went dark, this is meant to be because of basic copper carbonate.

[jsatan]

Also I had some burnt (melted) copper on the side, I added some salt and vinegar soln to clean it, That also turned a ncie cyan but with more of a blue colour.

I was thining this was copper acetate but thats a much more of a dark blue.

[Tetrahedrite]

The cyan blue colour you formed was an amorphous form of basic copper carbonate Cu2CO3(OH)2; this occassionally forms in nature and is called georgeite. Georgeite is, however, thermodynamically unstable with respect to the mineral malachite, and if left in solution all the georgeite will revert to malachite. Malachite has exactly the same formula, but is not amorphous (ie crystalline) and is green rather than blue.

 

You may not of realised it but you just did a nice little experiment in something we call the Ostwald Step rule!!!!

[jsatan]

cool. I was just messing about trying to get a copper salt from copper.

Would there of been an easyer way of doing this?

I'll look this Ostwald Step rule up, So was I about right with my reactions?

It was a total quess really, but what I dont get is why the blue made when I first eletro the copper is visable in water, this lead me to beleave I wasnt thinking right with the way I got to copper carbonate.

Hum.....

[jsatan]

now I'm messed up there is a thing as Copper Phosphate Hydroxide, lol. my poor brain

[jsatan]

I've dried my sample.

Is there a way to turn it back to the Georgeite?

I dont know if this is right but If I remove the water that would make it Georgeite wouldnt it? or it too hard to remove the water with out decompossing it?