Cart
Table of Contents
The yellow cascading precipitates are lead iodide, made from potassium iodide and lead nitrate. In the article "Using Large Glass Cylinders To Demonstrate Chemical Reactions" (pages 528-530), Wobbe de Vos describes a demonstration for observing the formation of precipitates. In a 0.5- or 1-liter glass cylinder almost completely filled with water a slow precipitation reaction involving two soluble salts occurs by adding a sample of one salt directly to the water and then placing some of the second salt in a filter inside a funnel that has been placed on top of the cylinder. Whereas setting up the experiment takes only a few minutes, the reaction may go on for an hour or more, displaying a slow but continuous formation process. The same set up can be used for a variety of redox, complex formation, and other reactions that produce a visible effect.