Sciencemadness Discussion Board - Uh, when did that happen?

Uh, when did that happen?

Upsilon - 17-9-2015 at 08:12

So I looked at copper(II) carbonate on Wikipedia today, and apparently it doesn't exist. Instead it is "basic copper carbonate" with a formula of Cu₃(OH)₂(CO₃)₂

I swear it wasn't like this when I last looked at the page probably a year ago. Is this legit, or is someone trolling Wikipedia? If it's real, how did it take this long to figure it out?

[Edited on 17-9-2015 by Upsilon]

Detonationology - 17-9-2015 at 08:17

https://simple.wikipedia.org/wiki/Copper(II)_carbonate

[Edited on 9-17-2015 by Detonationology]

MrHomeScientist - 17-9-2015 at 09:14

"It is made when copper is in air for a long time and turns green." lol

Yes basic copper carbonate is the correct term for what you run into in everyday chemistry. It's been known for quite some time that "actual" copper carbonate is nearly impossible to prepare; I think it requires some specialized apparatus and high pressure / vacuum conditions or some such. I can't find the reference right now. In wet chemistry you're always making the basic carbonate.

Blogfast's wish has finally come true!

Detonationology - 17-9-2015 at 11:21

Quote: Originally posted by MrHomeScientist

"It is made when copper is in air for a long time and turns green." lol

What is to be expected when using Wiki "Simple English" version

Upsilon - 17-9-2015 at 13:01

Well I just made some (too much actually lol) and the first batch I filtered (I had to split it up to filter it all since I made so much) was much bluer than the batches I filtered after (which are much more towards green). I think it's due to unreacted copper sulfate, I'll just have to keep washing it and see what happens.

Fulmen - 17-9-2015 at 13:30

Copper chemistry is complex, for more information read the page on regular Wikipedia. The composition of basic carbonates depends on the exact conditions.

Upsilon - 17-9-2015 at 14:16

Quote: Originally posted by Fulmen

Copper chemistry is complex, for more information read the page on regular Wikipedia. The composition of basic carbonates depends on the exact conditions.

The regular Wikipedia page for basic copper carbonate doesn't really give any information like that, are you referring to a different page?

Texium - 17-9-2015 at 14:41

Try looking around on here some more. There are many threads that have been started over the years dedicated to the finesse of figuring out how to make different variations of basic copper carbonate. You've been starting a lot of threads recently (I count four on the front page of today's posts that all could have been made part of existing threads). Perhaps try slowing down and searching the archives before immediately jumping into a new one.

[Edited on 9-17-2015 by zts16]

MrHomeScientist - 18-9-2015 at 05:28

Agreed. This forum is different than others in that we prefer you resurrect and add to old threads rather than starting new ones. That way all the information is in one place.

There's been tons of threads about copper chemistry lately. I'll bet that if there isn't one on the front page now, there will be on the next page. There was one recently where we went over a lot about this exact subject. The color of basic copper carbonate varies between blue and green, depending on reaction conditions. I myself have made many shades of the compound under what I thought were identical conditions.

Upsilon - 22-9-2015 at 09:33

My batch started forming these weird dark brownish patches. I reacted it with excess HCl anyway and they seem to have gone away. Now I have a really cool turquoise-colored solution. I wasn't sure if it was copper(II) chloride or not, until I looked it up and discovered that copper(II) chloride turns green depending on the concentration of Cl- ions present. Given that the solution has a large excess of HCl this makes sense. I'll evaporate it off and see what I get. Still, I don't know what those strange brown patches were. They dissolved completely in HCl.

Texium - 22-9-2015 at 09:57

Likely copper(II) oxide. Check other threads. I know for a fact that the exact problem has been documented here before, but it was over a year ago.

blogfast25 - 22-9-2015 at 10:00

Quote: Originally posted by Fulmen

Copper chemistry is complex, for more information read the page on regular Wikipedia. The composition of basic carbonates depends on the exact conditions.

A lot of people think that but it isn't true. There are only two basic copper carbonates: Malachite and Azurite.

https://en.wikipedia.org/wiki/Azurite

Azurite is very difficult to lab synthesise (I'm still trying!) and occurs as a rare mineral that tends to pseudomorph into Malachite.

aga - 22-9-2015 at 13:38

The Pressure !

ISTR that the Pressure affects the outcome.

Upsilon - 22-9-2015 at 13:51

Quote: Originally posted by blogfast25

Quote: Originally posted by Fulmen

Copper chemistry is complex, for more information read the page on regular Wikipedia. The composition of basic carbonates depends on the exact conditions.

That must be part of what I have. What I got was a kind of mix between the oxide-green malachite and that deep blue azurite. It is (or was, before I nuked it with HCl) some weird faded turquoise color that's much uglier than either of those two minerals.

blogfast25 - 22-9-2015 at 14:46

Quote: Originally posted by Upsilon

Sigh (insert 'dying of boredom' emoticon here)... No, you haven't. What you have is Malachite, pure and simple. The colour is highly deceptive because it depends on dry/wet, granulometry, lighting etc.

Whatever you use to precipitate the copper, carbonate or bicarbonate, you ALWAYS get Malachite. Don't believe it? Measure the CO<sub>2</sub> content on a sample and you'll see the light.