Copper nitrate is really bad stuff on storage. It absorbs water from the air and even storage in a tightly closed container can give problems.
A few years ago, I purchased copper(II) nitrate x-hydrate,. 1 kg, for cheap (spare material from an old lab). It was a little clumpy and the container
was old and tattered. I transferred all of it to a big glass jar with a metal cap and a plastic liner inside. I stored it in the attic in our house,
where in summer it can become quite hot (35 C or so) and in winter it can become as cold as 5 C.
One year later, I found the jar with the copper(II) nitrate and all of it was one big crystalline lump, hard like rock, sealed into the glass jar. I
think it has liquefied somehow (maybe in hot summer, melting in its own water of crystallization) and later it crystallized again, but now in one big
lump. It is impossible to get it out of the jar, without hitting that with a hammer. I did not do that, it still is there as one big lump, sealed in
its jar.
On storage, it does not really degrade chemically (it remains copper(II) nitrate, no decomposition to other copper compounds), but its physical form
is not stable. All samples of copper nitrate I had in the past turn into hard to handle lumps. I think that it is best to make a highly concentrated
solution of this, and store that instead of the solid form. Especially if you intend to do experiments with it in aqueous solution, then there is no
need to keep it in solid form.
[Edited on 11-7-25 by woelen] |
