I made some NH4SCN and permanganate mix with more accurate stechiometry and tested it.
Ammonium thiocyanate, which was rather old and has absorbed some water, was powdered as well as was potassium permanganate. Permanganate could be
powdered a little better, but the mortar used was rather small and larger one was not used. About 1g (slightly more probably) of thiocyanate and 10g
of permanganate were mixed together in a beaker with a glass spatula and put on a porcelain dish. This gave a mix of roughly 1:4 molar ratio, as the
more accurate scale was not available, 1:10 mass ratio of reactants was accepted as a good approximation, which produces desired molar ratio in a
reasonable approximation seeing as inaccuracy of the scale would put it out of balance anyway.
The mix was ignited with magnesium strip and burned vigorously with a lilac flame, typical for potassium compounds. It was a considerable improvement
over last test, which mostly smoldered. The residue left was dark, with a blue-green tint, it was also frothy, with a lot of gases trapped. The amount
of smoke emmited was considerable, although it did not overwhelm the fumehood. Nevertheless, the outdoor gas outlet, which leads from the fumehood's
ventillator, emmited enough of that smoke to produce a considerable cloud outside the school. The heat emmited cracked the porcelain dish, although it
was not in the good state at the beginning in the first place. (Dish with slight cracks was chosen so as not to destroy a new, good one) Acrid smell
was not noticed this time, although had the fumehood been opened later, the smell would probably have been still present.
This was a clear improvement. Next time I will try a urea based smoke mix, which may probably also be used to produce some noxious smoke (think NH3).
This time calculations will be easier though... |
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