In this demonstration, a chemical reaction is used to make a hidden message visible. The demonstration illustrates an entertaining application of chemical reactions in toys and everyday objects. It is also an interesting way to start the discussion of acids and bases, the pH scale, or acid-base indicators. Invisible ink has been used in espionage to send messages that cannot easily be read by enemies.
In this demo, a polyethylene rod is charged by rubbing with wool. The charged rod is then used to bend a stream of water flowing from a tap. Different substances have different attractions for... read more
Categories: Teacher Demonstration
Osmosis, the movement of a solvent (usually water) across a semi-permeable membrane from an area of higher solvent concentration to an area of lower solvent concentration, is key in the maintenance... read more