Potassium and iodine

Explosion of potassium and iodine

Scientific name: Demonstration of a violent raction between potassium and iodine


Alkali Metals - 23 Reaction between Potassium and Iodine

by Royal Society Of Chemistry

K plus Iodine

by chemBruins


Wear lab gloves and eye protection. There is an explosion - use a protection shield!

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

Reaction formula

2K + I2 → 2KI


  1. Iodine
  2. Potassium

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. Place a plate in a protective box.
  2. Put some iodine crystals onto the plate.
  3. Put a piece of potassium onto the plate near iodine.
  4. Push the piece of potassium using a long glass rod and thus place it into a handful of iodine. A few seconds later a violent explosion occurs.

Scientific background

Potassium reacts with iodine forming potassium iodide. This is a very violent reaction, it occurs with an explosion. A lilac colored flame can be seen in this demonstration - it is the characteristic color of potassium in a flame.


Published on 24 June 2015

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