Sciencemadness Discussion Board

Purple floating liquid on CuCO3?

Copper - 29-12-2015 at 19:15

Hello all,
After synthesis and filtration of CuCO3 I heated it on a hot plate. The solid melted ??? and formed a strange purple floating layer on the top ???
Does anyone know the cause of that?
Thanks

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blogfast25 - 29-12-2015 at 19:23

You need to describe your synthesis first. W/o it no one can make any significant pronouncements re. what is causing the purple colour.

Copper - 29-12-2015 at 19:25

It's the standard NaHCO3 and CuSO4 precipitation.

blogfast25 - 29-12-2015 at 19:42

Quote: Originally posted by Copper  
It's the standard NaHCO3 and CuSO4 precipitation.


You need to specify quantities.

I think poorly washed basic copper carbonate (CuCO3 DOESN'T exist, only basic copper carbonate does) gave cuprate which is blue. Blue + green gives purple.

Copper - 29-12-2015 at 19:52

Ok thanks,
As I had a good amount of very concentrated (near saturated) copper sulfate solution I just added baking soda until effervescence ceased. It was filtered using coffee filters and washed twice with distilled water. Then it was scooped and placed into the 100mL beaker.
Also I don't think blue and green will give purple, instead it gives turquoise.

MolecularWorld - 29-12-2015 at 21:06

Remarkable.
Quote: Originally posted by blogfast25  
...shmucks of the 'i put cuso4 in amonia and gets brown stuff, elp pleaze?' variety...

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Quote: Originally posted by blogfast25  
Blue + green gives purple.
Dubious.

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blogfast25 - 30-12-2015 at 06:06

Quote: Originally posted by MolecularWorld  
Remarkable.



No.

Many know I have 'a thing' for basic copper carbonate, primarily because of the stubborn belief in the non-existent CuCO3.

See also this lengthy thread:

http://www.sciencemadness.org/talk/viewthread.php?tid=50822

Methinks you have a bit of a 'grudge management problem' that might be clouding your judgement somewhat.

[Edited on 30-12-2015 by blogfast25]

Boffis - 30-12-2015 at 15:14

There are several normal double carbonates of copper and other elements; check out Juangodoyite it ranges from deep blue violet to a lilac colour. It is Na2Cu(CO3)2 but sparingly soluble but other ratios of Na to Cu may be more soluble, looks reasonable.


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blogfast25 - 30-12-2015 at 15:55

Quote: Originally posted by Boffis  
There are several normal double carbonates of copper and other elements; check out Juangodoyite it ranges from deep blue violet to a lilac colour. It is Na2Cu(CO3)2 but sparingly soluble but other ratios of Na to Cu may be more soluble, looks reasonable.




Nice find and I'd never heard of that mineral before. But I find it hard to see how it could form in OP's conditions, though...

Velzee - 1-1-2016 at 15:16

Quote: Originally posted by Boffis  
There are several normal double carbonates of copper and other elements; check out Juangodoyite it ranges from deep blue violet to a lilac colour. It is Na2Cu(CO3)2 but sparingly soluble but other ratios of Na to Cu may be more soluble, looks reasonable.




Are there any methods of making these double carbonates?

morsagh - 2-1-2016 at 00:34

Maybe heating mixture of Cu2(OH)2CO3+ Na2CO3+ NaHCO3 up to boiling point of water but under calcination of NaHCO3 it is just a guess but not so hard to try so good luck.