Precipitate Formation

We add potassium iodide and lead(II) nitrate to the opposite sides of a Petri dish filled with water to see how quickly they diffuse. When added to the water, the chemicals spread through the dish and when they meet they react to form lead iodide, which precipitates out of the solution. The position of the precipitate lets us see how quickly they diffused relative to each other.

Chemistry - Atoms And Bonding - Learning Points.
Salts contain metals and non-metals.
Soluble salts dissociate into ions that are free to move in solution.
Ions move at different speeds depending on their size and charge.
Not all salts are soluble and a precipitate is an insoluble salt that forms during a reaction.

A Twig Experiment Film.
Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.