[Hanzolot]

Hi there!

We were asked to identify an unknown copper (II) compound, using spectophotometry. The information that we have on the compound is:

-It's black
-Metallic lustre
-Smelled somewhat reminiscent of stale urine
-Not too hard (pieces that were clumped together were broken up without too much difficulty)
-A salt or hydride
- Around 23.6% Copper (II)
-Very soluble in water (solution turned a light blue), ammonia (turned a dark blue, not as soluble as the others), and H2SO4 (light blue). Initially, when breaking up, it turned a brownish-green.
-Around 0.28 absorbance at 585 nm.

We've tried Googling every compound we came across, and it's not coming out clear which compound it could be.

If any brilliant chemist on here has an idea of what it is, or where to find out what it is, it'd be much appreciated.

Thanks,
Hans Lafford

[Borek]

-Around 0.28 absorbance at 585 nm.

This information - as given - is completely useless.

[Hanzolot]

This information - as given - is completely useless.

That's why I included the rest of the information too.  

[Albert]

-It's black

The only black copper compound I know it's cupric oxide (CuO), which I think to be also quite soluble in water, but it's certainly soluble in sulfuric acid.

However, every time I saw cupric oxide, it was a black powder.

[Borek]

The only black copper compound I know it's cupric oxide (CuO), which I think to be also quite soluble in water, but it's certainly soluble in sulfuric acid.

However, every time I saw cupric oxide, it was a black powder.

Wrong smell, way to low molar mass.

[Albert]

Mmm, I'm in a quandary.

I've looked up my old inorganic chemistry book: the author talks about Copper (II) Bromide, as a black compound. Moreover it should contain approximately the percentage of copper mentioned by Hanzolot.

On the other hand, I have to say I've never seen it but I think I've read something where it was described as a very dangerous and toxic, though stable, compound.

[Borek]

I've looked up my old inorganic chemistry book: the author talks about Copper (II) Bromide, as a black compound.

http://physchem.ox.ac.uk/MSDS/CO/copper_II_bromide.html

Moreover it should contain approximately the percentage of copper mentioned by Hanzolot.

Over 5% off.

Note original remark about urine smell - that may suggest some ammonia or urea present, perhaps as complexing agent.