Fun Halloween chemical monsters

Try to solve the mystery of each one!

Safe­ty pre­cau­tions

Warn­ing! Only un­der adult su­per­vi­sion.


  • beaker;
  • so­lu­tions of potas­si­um io­dide;
  • sodi­um thio­sul­fate;
  • starch and iron(III) chlo­ride;
  • cal­ci­um glu­conate tablets;
  • dry fuel;
  • mar­ble and flu­o­rite pow­ders;
  • skull sten­cil.

Step-by-step in­struc­tions

Mix so­lu­tions of potas­si­um io­dide, sodi­um thio­sul­fate, starch, and iron(III) chlo­ride in a beaker. Af­ter a few sec­onds, the mix­ture is in­stant­ly plunged into spooky dark­ness!

Heat cal­ci­um glu­conate with dry fuel – a writhing black "snake" be­gins to grow right in front of you!

Pour mar­ble and flu­o­rite pow­ders onto a sten­cil to make a white skull. When heat­ed, it starts to glow dif­fer­ent col­ors!

Process de­scrip­tion

Iron(III) chlo­ride makes potas­si­um io­dide turn into molec­u­lar io­dine. When it binds to starch, a new dark blue com­pound ap­pears, which gives rise to the sud­den gloom.

The dry fuel heats the cal­ci­um glu­conate, mak­ing it de­com­pose. This yields coal and cal­ci­um ox­ide, which are foamed by the emit­ted car­bon diox­ide and wa­ter va­por. This hap­pens so quick­ly that the black “snake” grows right be­fore your eyes!

Elec­trons in mar­ble and flu­o­rite pos­sess ex­cess en­er­gy that has ac­cu­mu­lat­ed for many years un­der the in­flu­ence of the en­vi­ron­ment. When these min­er­als are heat­ed, their elec­trons re­lease their ex­cess en­er­gy in the form of light.

Sim­i­lar ex­per­i­ments are in­clud­ed in the “Egyp­tian night,” “Chem­istry of mon­sters,” and “Chem­istry & light” sets from the MEL Sci­ence sub­scrip­tion.