chornedsnorkack - 7-6-2013 at 05:32
Marsh test is supposed to be specific for arsenic, which is distinguished from antimony and bismuth by appearing on geated glass rather than cold.
Why only fifth main group?
Say, germane... can Marsh test conditions reduce germanium compounds to germane? Or hydrogen telluride - will tellurium not be reduced in Marsh test?
Or is hydrogen telluride too soluble and too strong acid to be carried out of solution?
eidolonicaurum - 4-1-2014 at 10:43
With the germanium compounds, they are very similar to silicon. So will marsh test conditions affect silicon compounds in the desired way? The same is
true for tellurium. Will it react in the same way? Compare with selenium and sulphur?
blogfast25 - 4-1-2014 at 11:19
GeH4 appears to start decomposing at about 600 K (Wiki), so a hot surface would do it. H2Te is an endothermic compound, so it too probably decomposes
at a hot surface.
Question is, will Ge and Te compounds be reduced to their hydrides in Marsh conditions, which is based on the reduction of As2O3 with Zn and acid? The
best (but not perfect) advisor here is the relevant reduction potentials.
Zn<sup>2+</sup> + 2 e === > Zn … E = - 0.7618 V
Te + 2 H<sup>+</sup> + 2 e === > H<sub>2</sub>Te … E = - 0.793 V
This would suggest that even if Zn could reduce Te (IV or VI) compounds to Te, Zn cannot further reduce Te to hydrogen telluride.
For germanium I have no data at hand.
[Edited on 4-1-2014 by blogfast25]