Modern Alchemy - Contact Explosive

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Nitrogen Triiodide is an extremely sensitive explosive compound that, when dry, can be detonated by the lightest of touches or vibrations. For this reason, it should never be contained or transported and we are not aware of any industrial uses.

A quantity of NI3 was prepared in the Ri Prep Room before being laid out to dry in the famous Lecture Theatre. This process took over two hours and, due to the extreme shock-sensitivity of the material, we were only able to attempt the reaction on this scale once. The crew were forced to wear ear defenders at all times in case the material spontaneously exploded.  

As Dr Peter Wothers initiates the reaction, the Nitrogen Triiodide detonates incredibly quickly in a fraction of a second to release a purple cloud of iodine vapour into the room.

Peter Wothers explains further:

"To tie in with the theme of the first Christmas Lecture (Air), I wanted to show the rapid production of a gas, but unfortunately almost all gases are colourless.  The rapid production of iodine vapour from NI3 seemed like the perfect solution.  The most amazing thing for me was the delay visible from the slow-mo footage before the force of the explosion really hit me in the chest!"

Devised to promote the 2012 Christmas Lectures, this is one of three large-scale, chemistry demos that were too big (or too dangerous!) to perform in the Ri Lecture Theatre in front of 400 young people.

This experiment was undertaken under the supervision of professionals and should not be replicated. 

The production of this video was supported by:





Dr Peter Wothers
Royal Institution, London
Filmed in:
The Theatre

The Refinery

cc_by-nc-sa License: Creative Commons

Related Links and Media

  • The Modern Alchemist: 2012 Christmas Lectures

    Image: The Royal Institution


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