Hi
I have a question on reduction of ag2o - I very much appreciate your comments:
I am trying to get the (presumably) ag2o tarnish off from greyish silver micro particles. Being a physicist, I had to look it up and it seems easy:
heat it in air, or n2, to 450 K or so , and the ag2o will convert to ag.
but somehow it doesn't work. I put the sample in an oven (air) at 470K, it sits there for an hour - but it doesn't change its colour a bit (measured
in a spectrometer).
any ideas? is 1 hour not sufficiently long?
thanks
sippinelementcollector1 - 30-5-2014 at 12:16
Fine powders of substances are very often darker than their respective bulk metals.deltaH - 30-5-2014 at 12:32
Acording to wikipedia, silver oxide decomposes at 553K (starts?), so you may want to calcine it at about 600K.Brain&Force - 30-5-2014 at 14:43
Fine powders of substances are very often darker than their respective bulk metals.
Powdered silver is dark gray. When did you get the particles? They're probably fine, unless you really need to get rid of any and all oxides.
If you want to make silver powder, try dissolving silver metal in nitric acid, then precipitating it back out with sodium metabisulfite solution.UnintentionalChaos - 30-5-2014 at 18:46
try dissolving silver metal in nitric acid, then precipitating it back out with sodium metabisulfite solution.
Sounds like a good way to make a mess. Silver doesn't work like gold in this regard.APO - 31-5-2014 at 02:14
Hydrogen is good for metal oxide reduction if your positive oxides are making it dark. Some good videos are avalible on youtube. Just look around.unionised - 31-5-2014 at 02:48
Just a thought, but the tarnish that forms on silver isn't usually the oxide so this bit of the OP is
wrong
"I am trying to get the (presumably) ag2o tarnish off from greyish silver micro particles"
It's not likely to be Ag2O.
It's more likely to be Ag2S
Heating in air might oxidise the sulphide to SO2 and leave the silver behind.
