Resumen de Red shoe-blue shoe:: An Acid-Base Demonstration with a Fashionable Twist

Calvin E. Uzelmeier, Arthur C. Breyer

• This demonstration illustrates that acid-base indicators may come in many forms, and further exhibits the reversible effects which acids and bases may have on the colors of such indicators. The demonstration involves the dyeing of an object in an indicator, congo red, which causes it to change color from red to dark blue at pH less than 3.0 to 5.0. When the red object is submerged in an acidic solution which has been colored red, the object turns blue. When the blue object is submerged in a basic solution which has been colored blue, the object returns to its original red. Variations on these procedures are presented to make it appropriate for a wide range of ages and presentation styles.