Introduce the significance of pH indicators with this colorful demonstration of solubility, equilibrium, Le Châtelier's principle, and acid-base chemistry. Students observe a household antacid cycle through a rainbow of colorful pH changes. Lesson can be extended to study the reaction at different temperatures to bring in kinetics and thermodynamics. A great demo that can be used several times during the curriculum. Materials are sufficient for 5 demonstrations. Student worksheets included.