Blue Bottle Experiment

The blue bottle experiment is a classic chemistry demonstration that has been recently used as a guided inquiry experiment. Generally, a mixture of dextrose, Methylene blue and NaOH is used. The reaction is explained in detail in ( Campbell, J. A. J. Chem. Educ. 1963, 40, 578–583. ) We provided a set of instructions, and then used a talk aloud strategy to follow the construction of student mental models during the experiment. Initial interviews have yielded the following observations.

• Participants eventually recognized the color change was a chemical reaction (relationship).
• Participants recognized that the length of time that the bottle is shaken was related to the length of time the flask remains blue ( a relationship).
• Participants focused on the individual chemical components as important referents. they seemed to think that the explanation of their observations hinged on the properties of the specific compounds.
• One participant viewed the reaction as reversible, and included the idea of equilibrium in her explanation.