In this Activity, students observe UV-sensitive beads that have been melted into flat disks, explore the temperature behavior of the disks, and then use the disks to investigate the effectiveness of different sunscreens. The Activity shows applications of chemistry in the real world.
When acidic dichromate and iodide solutions are mixed, no immediate reaction takes place. Addition of iron(II) solution brings about rapid formation of brown triiodide.
An acidified iron(III) solution is added to iodide solution to see if oxidation to triiodide will occur.