UV Light Initiated Explosive Reaction Between Hydrogen and Chlorine Gas

This is a great demonstration showing the explosive reaction of a mixture of hydrogen and chlorine gas that first need to be initiated with Ultra Violet (UV) light. The reaction does not take place when light is shone from the visible wavelength spectrum but it immediately starts when the higher frequency UV light is shone. The UV light breaks the bonds of the Chlorine gas molecules which then seek to bond with the hydrogen gas molecules. This reaction results in an explosion that launches a rubber stopper across the lecture hall!