Jor - 26-10-2010 at 06:07
I have read that KCN can be used to reduce the oxides of metals to the metal, by fusion in a crucible.
As I have some KCN , I am interested in this method. I am particulary interested in making the following metals:
- Vanadium (from V2O5)
- Rhenium (from NH4ReO4)
- Germanium (from GeO2)
- Arsenic (from As4O10)
My first question is, wich of these will go completely go to the metal, and not some lower oxide. For example I suspect you won't get vanadium, but
some lower oxide like VO or V2O3. The same goes for rhenium and arsenic.
The second question is: does anyone have experience with this reaction. I am for example not sure how violent these reactions are, wich is especially
worrying when using V2O5.
I don't see this as a waste of KCN, I need al these metals for my collection in a small amount (1g is enough), wich probably consumes only small
amounts of KCN, and the free elements are expensive.
I have tried to find some references, but google doesn't yeild anything, and I won't have access to the uni database for a week. 
not_important - 26-10-2010 at 14:46
Vanadium is far too reactive, combining with oxygen, nitrogen, and carbon.
Rhenium is doubtful, and the volatility of the oxide might cause trouble.
Germanium likely would work, carbon reduces the oxide to elemental Ge. Arsenic should be reduced as well, but the vapour pressure at the needed
temperatures is high enough that it will sublime.
Check old chem and mineralogy books from 1860-1930, available at places such as the Internet Archive and Google books.