Pharaoh's snake

A solid substance burns producing a snake-like mass.

Scientific name: Mercury thiocyanate decomposes under heating.

YouTube

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Safety

Since mercury thiocyanate and products of its decomposing are extremely toxic this experiment must performed only in a fume hood. Wear lab gloves and eye protection.There is a serious fire risk - a fire extinguisher should be ready.

The resulting product are very toxic! Several children dead by mistakenly eating the resulting solid.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

Hg(SCN)2 → 2HgS + CS2 + C3N4

CS2 + 3O2 → CO2 + 2SO2

HgS + O2 → Hg + SO2

2C3N4 → 3(CN)2 + N2

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. To perform this experiment you need only one reagent - mercury thiocyanate.
  2. Since mercury thiocyanate and products of its decomposing are extremely toxic this experiment must performed only in a fume hood.
  3. Put some mercury thiocyanate on a non-combustible surface.
  4. Light up the kindling.
  5. Ignite the mercury thiocyanate .

Scientific background

The pharaoh snake is a solid-like substance consisting of mercury thiocyanate decomposition products. When a solid tablet of mercury thiocyanate is exposed to heat it burns with a blue flame. The decomposition reaction looks as follows:

Hg(SCN)2 → 2HgS + CS2 + C3N4

The first two products can react with oxygen of air:

CS2 + 3O2 → CO2 + 2SO2

HgS + O2 → Hg + SO2

Dicyan breaks down under heating:

2C3N4 → 3(CN)2 + N2

Danger:
Coolness:
Difficulty:

Published on 18 March 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst