reactions

Reaction of nickel with iodine

Powdered nickel and powdered iodine are mixed together. Adding drops of water to the mixture fails to initiate a reaction.

Zinc iodine reaction

Powdered zinc and solid iodine are mixed and no reaction is observed. Adding water to the mixture initiates a reaction.

Aluminum iodine reaction

Powdered aluminum and solid iodine are mixed and no reaction is observed. Adding water to the mixture initiates a reaction.

Hydrogen and chlorine cannon

Hydrogen and chlorine gases can be mixed together without reacting, but when the mixture is struck with bright light, it reacts explosively.