“Detonation by water” experiment
How to ignite magnesium powder and silver nitrate with a water drop
A spectacular chemistry experiment with deep historical roots.
Safety rules must be observed when working with explosive substances and mixtures.
Reagents and equipment:
- silver nitrate (2 g);
- magnesium powder (2 g);
In the beaker, we mix magnesium powder and silver nitrate in the proportion of 1:1. Then we drip water on to the resulting mixture – it bursts into flame!
Magnesium is a very reactive metal, so it forces less reactive metals out of their salts (for example from silver nitrate). Water is the initiator of this reaction. Silver nitrate dissolves in water, and magnesium forces silver out of its salt. In the course of the reaction, heat is released, which is sufficient for the breakdown of silver nitrate into nitrogen (IV) dioxide, metallic silver and oxygen, which oxidizes metallic magnesium. A large amount of heat and light are released. This property of the reaction of magnesium with any oxidizers was used in the first camera flashes. But this mixture is very dangerous, as the moisture in the air can easily set off the reaction:
2Mg + 2AgNO₃ = 2MgO + 2NО₂ + 2Ag
2AgNO₃ = 2NО₂ + 2Ag + О₂