Caption:
Aluminium reacts with iodine, 2 of 5. Powdered aluminium metal (Al) and iodine (I2) are mixed together and placed in a watch glass. A drop of water is used to initiate the synthesis reaction: Al + I2 -> Al2I6. It is an exothermic redox reaction that produces a lot of heat so that iodine sublimates and forms a violet vapour.