Pictures of Ingredients
Indicator Color Chart
Does not Include:
This is a honors or advanced level Biology Lab to study acids, bases, buffers and the pH scale. I accompany this with a CER graphic organizer to answer the question "Which antacid acts as the best buffer?" To complete the CER post-lab I provide students with pictures of the ingredients to include in their reasoning.
This lab gives great results. The Mylanta, Tums and Rolaids contain weak bases which neutralize the HCl for a short time (10-20 drops). The alka-seltzer is a buffered solution which resists changes in pH. Most groups get well over 100 drops of HCl in the alka-seltzer without even a slight color change. It makes a big statement that students easily grasp.
To prepare the indicator just boil a 5-7 full leaves of red cabbage in water until the water becomes purple. The indicator color chart is included at the end of the lab.