Disappearing Rainbow

Assassin's Bottle title card
Ramping Up the Disappearing Rainbow with the Assassin’s Water Bottle
// Tuesday, September 16, 2025 • Tom Kuntzleman
The disappearing rainbow1 is a wonderful chemistry demonstration previously featured here on ChemEdX.2-4 In this experiment, a colorless solution of NaOH is poured into a row of flasks, each containing a different acid–base indicator.