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acids/bases

Ramping Up the Disappearing Rainbow with the Assassin’s Water Bottle

Tom Kuntzleman | Tue, 09/16/2025 - 09:44

What happens when chemistry and illusion collide? In The Disappearing Rainbow, a simple acid–base demonstration transforms into a spellbinding performance. With a single pour, colorless liquids bloom into a vibrant rainbow—then vanish in an instant. Now, with the arrival of the “Assassin’s water bottle,” this classic demo gets a modern twist that makes the magic easier (and cleaner) than ever.

Three Turmeric Treats

Dean Campbell | Wed, 07/16/2025 - 08:32

Curcumin, found in the spice turmeric, varies from yellow in acidic conditions to orange-red in basic conditions. This enables curcumin to be used in many acid-base demonstrations and incorporate ideas such as hidden messages and mechanochemistry.

Chemical Activities Involving Reversible Thermochromic Pigments

Dean Campbell | Wed, 08/16/2023 - 07:17

The color of a thermochromic system depends on its temperature. The colors of leuco dye-based systems can also be influenced by adding acids or bases to the thermochromic reactions. These can be used to create colorful demonstrations of acid-base chemistry. Thermochromism found in color changing cups can also be used to visualize heat flow, and therefore thermodynamic principles, associated with stretching and contracting elastomers.

Seashell Chemistry

Tom Kuntzleman | Thu, 06/01/2023 - 14:15

Placing dry ice in limewater is a great demonstration to accompany discussions on a variety of chemical topics, including the impact of ocean acidification on marine organisms that depend upon the formation of CaCO3.