Hydrogen and chlorine gases can be mixed together without reacting, but when the mixture is struck with bright light, it reacts explosively.
This brief animation illustrates the chain reaction that occurs when hydrogen and chlorine gases react.
Sulfur is burned in a deflagrating spoon in a flask, forming sulfur dioxide in the synthesis reaction.
A piece of copper metal is heated in a flame and oxidized to black copper oxide by air. The oxidized copper is reduced when placed in a hydrogen atmosphere. When removed from the hydrogen atmosphere, the metal is again oxidized.
Simply touching dry nitrogen triiodide with a feather causes it to explode. Includes slow-motion replay of explosion.