Sciencemadness Discussion Board

CuCO3+CuNO3= purple liquid?

Camroc37 - 23-8-2015 at 18:04


A weird reaction happened to me today: Copper Nitrate reacted with Copper Carbonate to form a purple liquid.
They were both fairly and not in solution, but the Copper Nitrate had just been recrystallized so it was a little wet.
Any ideas? This may be a simple reaction, but I don't know of it.

Volanschemia - 23-8-2015 at 19:48

I'm guessing some kind of complex?
Copper(II) Nitrate is quite hygroscopic, so it will pull in water.

woelen - 23-8-2015 at 21:52

Were the salts commercial samples or home made? Purity can be an issue.
True copper carbonate is not commonly available and is hard to make. The commercial material is a basic carbonate.

The presence of ammonium ions may cause appearance of a purple color, due to formation of the tetrammine complex of copper(II), which has a very deep blue/indigo color.

Camroc37 - 24-8-2015 at 12:59

Quote: Originally posted by woelen  
Were the salts commercial samples or home made? Purity can be an issue.
True copper carbonate is not commonly available and is hard to make. The commercial material is a basic carbonate.

The presence of ammonium ions may cause appearance of a purple color, due to formation of the tetrammine complex of copper(II), which has a very deep blue/indigo color.

Both were homemade.

Volanschemia - 24-8-2015 at 14:50

How exactly did you make them? It's probably impurities from the synthesis that is causing the complex.

woelen - 24-8-2015 at 23:14

We indeed need more information before we will be able to provide insight in your reaction. The nature of the impurities can have a strong impact on the observations.