Inorganic gas puzzle

A postgraduate student has posted a research problem on sci.chem.analytical, which Sciencebase’s chemically aware readers might be interested in puzzling over.

The student seems to have discovered a new inorganic gas.

Apparently, he heated a zeolite which consists Analcime, feldspar and silica to 500 Celsius. X-ray fluorescence shows the presence of Si Al K Ca Na S Ti and Fe. When the heated material is dissolved in HCl, a gas is evolved with the following properties (summarized by M Farooq on CHEMED-L):

(a) It smells like ammonia

(b) It gives a precipitate with calcium hydroxide which re-dissolves in HCl

(c) It does not decolorize potassium permanganate solution

(These properties would suggest carbon dioxide, but….)

(d) It can be collected over water and has an ammoniacal smell but is not as irritating as ammonia

(e) The gas does not react with silver chloride in solution (unlike ammonia) but can colorize silver nitrate solution (goes from colorless to weak yellow, similar to iron(III) ions in solution)

It might be a gaseous hydride and is almost certainly not an organic compound as all would be destroyed at 500 Celsius. Arsine impuritues are unlikely as the X-ray fluorescence did not reveal arsenic.

So, what is it?