Blauregen – Ein ästhetisches Experiment zum Einfluss der Lösemittelpolarität auf die Farbreaktion im thermochromen Dreikomponentensystem.

Thermochromic mixtures are designed in a way that a color former is reversibly or irreversibly converted from a colorless to a colored state when combined with a developer under the influence of heat. In a simple experiment, the influence of solvent polarity on the color behavior of thermochromic mixtures is shown. In a non‐polar solvent, the color former is separated from a solid phase of the developer. When a polar solvent is added, the developer dissolves and is transferred to the liquid phase of the color former, creating the colored compound that is stabilized in the polar phase. Further addition of polar solvent leads to discoloration since the developer is more soluble in the solvent mixture. Therefore, the metastable dye‐developer complex dissociates, and the mixture gets colorless again. This aesthetic experiment provides a motivating introduction to the subject of thermochromic mixtures. [ABSTRACT FROM AUTHOR]