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.
Related Resources:
Teacher Demo/Student Activity: Bending Water
Categories: Lab/Student Activity, Teacher Demonstration
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
Teacher Demo: Osmosis Across a Semi-permeable Membrane
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
Teacher Demo: Acid-Base Rainbow
Categories: Teacher Demonstration
This quick demonstration is a highly visual illustration of the use of acid-base indicators to determine pH. Milk of magnesia is mostly a suspension of magnesium hydroxide in water. Magnesium... read more