"Purple Haze" Reaction of Iodine and Aluminum

The first paragraph introduces a simple chemistry demonstration involving two elements, iodine and aluminum, with a specific ratio of three parts aluminum to one part iodine. The presenter discusses the practicality of using this demonstration to utilize excess iodine stored in a school's storeroom. The setup is quick, and the reaction can be used to teach various chemistry concepts, including synthesis, compound formation, and charge analysis. The iodine must be ground into a fine powder using a mortar and pestle, and care is taken to keep the iodine and aluminum separate until the experiment is conducted to prevent premature activation, especially in humid conditions. The demonstration involves mixing the two elements and adding a few drops of water, which triggers a reaction that produces a purple vapor. The presenter emphasizes the importance of safety and practice when conducting the demonstration and engaging students in asking questions and making predictions. The chemical reaction described is the formation of aluminum iodide.

The second paragraph focuses on the educational aspect of the demonstration, explaining the concept of diatomic elements to students who may not be familiar with it. The presenter suggests that this is an opportunity to explain that some elements exist in a diatomic form, rather than as individual atoms. The paragraph also touches on the process of formula writing and balancing chemical equations, which could be part of the educational activity depending on the students' current stage in their chemistry course. The presenter may guide students through balancing the equation for aluminum iodide formation, which could be an exercise in a formula writing unit.