nitroglycol - 27-11-2005 at 18:04
Recently I came into the possession of a nice 500 mL volumetric flask. Only thing is, it was used to store silver nitrate, and has deposits on the
inside surface that I presume to be silver. I suppose given silver's inertness this is more of an aesthetic issue than anything, but I still want
to get it clean, and that same inertness makes it darn difficult to do so. Yesterday I filled it with a mix of vinegar and "green" bleach (a
hydrogen peroxide solution of unspecified concentration), hoping that this would oxidize the silver, which in turn would allow it to be dissolved by
the vinegar. So far, though, no visible changes have occurred. I know nitric acid should work, but finding that would probably be much more difficult
than getting a new flask.
Any suggestions?
neutrino - 27-11-2005 at 18:23
Chloride will form insoluable AgCl percipitates which will block further chemical action.
Hot, concentrated sulfuric acid may work. Otherwise, I suggest to start scrubbing.
The_Davster - 27-11-2005 at 18:47
Do you have acess to potassium permanganate? An acidic solution of it should dissolve silver.
chochu3 - 27-11-2005 at 22:42
Nitric acid will also work. In lab we did some test which made a silver mirror on the bottom of the test tube in organic lab, we then instructed to
use nitric acid to remove it.
unionised - 28-11-2005 at 00:23
Sodium thiosulphate (photographic fixer) might do a useful job of removing any silver salts present.
If there is free silver present (and I expect there will be) you might be able to oxidise it with iodine then disolve the iodide with thiosulphate.
You might need to do this a few times if the deposit is thick.
nitroglycol - 28-11-2005 at 02:55
Thanks, unionized! That sounds like the most practical approach (scrubbing is only possible on the outside and the neck- the inside of the main part
of the flask is rather hard to reach).
unionised - 28-11-2005 at 12:51
If it doesn't work I recommend scrubbing the inside of the flask using a slurry of lead-shot and salt in water. Used for many years (centuries)
by butlers cleaning decanters. Sometimes the old ways are the best.
BTW, I'm English so its UnioniSed.