[flick-a-bic]

I took Cu(NO3)2 and Ni(NO3)2 (both are hydrates) in roughly 1:1 ratio. Mixed in a little Di H2O. Then added methyl ammonium iodide in excess. Got blackish.

Then I added some concentrate sulfuric acid and WOOF, a cloud of purple smoke formed. I vented that out. I didn't add any more acid, so I don't know if the purple smoke formed in completion.

Now I have a black powder/maybe crystals.

1.) what was the purple smoke? Figured it out. Obviously molecular iodine. I think I have iodate in solution as well. (from color)
2.) Any idea what formed before the acid?
3.) What could have 'grown' after the acid?

[Hunter2]

The Cu²⁺ react with Iodide I^- to Iodine. This was also seen as the fume by adding sulfuric acid. The acid set free at least HI what decompose by copper. There is nothing more grown. The solution contain still Nitrate , Methylammonium ions,copper and Nickel, additionally Sulfate and some insolouble Copper-I-iodide CuI.