Lead metal is placed in a silver nitrate solution.
Granular zinc and powdered iodine are mixed together. Adding drops of water to the mixture initiates a reaction.
Powdered zinc and solid iodine are mixed and no reaction is observed. Adding water to the mixture initiates a reaction.
Sulfur is burned in a deflagrating spoon in a flask, forming sulfur dioxide in the synthesis reaction.
Powdered aluminum and solid iodine are mixed and no reaction is observed. Adding water to the mixture initiates a 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.
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.