Tamed reaction between sodium and water
As we learnt from the very beginning of our chemistry classes, alkali metal reacting with water could result in explosion. The following video shows what happened when a solid sodium was thrown into water.
Warning: Do not try what he did in the video, it is really dangerous.
The reaction is explosive that we are unable to observe each stage of the reaction, but now explosion can be prevented when alkali metal in water is put under specific controlled conditions.
By adding a small amount of hexanol or place the metal gently on water on an argon atmosphere. The team that found this way to control the reaction record the reaction by high-speed camera imaging and visible and infrared spectroscopy to observe the reaction.
The following video shows how is the reaction looks like when it is not explosive. You can see the blue color of the solvated electrons in the solution.
In secondary school you may have seen the demonstration of this reaction, but what you can see from the demonstration and this video are really different. You can see the blue surface of the metal, you can see the metal become red gradually and become a transparent drop, then burst at last.
By carrying out this experiment in controlled conditions, we can learn more about the reaction between alkali metal and water.
Check out here for more details.