NEEDED
- Mercury thiocyanate : Hg(SCN)2
PROCEDURE
Take some Hg(SCN)2 (mercury is toxic, so wear
gloves!) and set it on fire with lighter. The reaction
starts immediately.
The resulting "snakes" contain mostly carbon
nitride, but the mercury is present as metal and is
releasing mercury vapour, so the material has to
be disposed by special chemical waste procedures.
COMMENTS
Certainly, one of the most spectacular and
actually quite frightening reaction. Since
mercury is toxic however, the experiment
should only be conducted with extreme care
and only if a proper waste disposal is available.
The version described in experiment
ME5
is
by far not as breathtaking, but apart from the
smoke not poisonous at all.
Hg(SCN)2 decomposes into HgS, CS2, and C3N4
with latter being the actual "snake". The products
decompose further:
C3N4 → 3 NCCN + N2 ( → cyanide)
HgS + O2 → Hg + SO2
CS2 + 3 O2 → CO2 + 2 SO2