Baking Soda Challenge

The Baking Soda design activity is a week-long, chemistry-oriented design task that comes from the Challenges of Physical Science curriculum. Watch MOVIE 1 for an Quick Peek of the design scenario that asks students to act as a consultant to a baker who needs a replacement for yeast to make her bread rise. Specifically, teams must determine the ratio of baking soda and vinegar that will produce the greatest volume of the bubbly carbon-dioxide brew that forms after mixing. After working experimentally with a balloon, thermometer, and setup where the bubbly mix (detergent added to make bubbles last) raises a ping-pong ball up a transparent plastic tube, teams are introduced a paper-based model of molecules at work (sodium bicarbonate + acetic acid). This gives students a mental model of the reaction that also helps them predict the optimal ratio for a given total mass of ingredients that yields maximum gas production and minimal residue (after-taste) for their client.

DITC's Baking Soda section holds the following:

•  Introducing Baking Soda  Students are introduced to the challenge, and begin a "messing about" investigation with the two ingredients, baking soda and vinegar, by observing the products and quantities once they react.
•  Investigating Reaction's Products  Students conduct more qualitative experiments to determine the nature of the reaction (endothermic) and the gas that gets produced.
•  Finding the Optimal Mix  Students use a cylindrical plastic tube and ping-pong ball to measure the volume of gas produced with different proportions of the active ingredients. All teams display on a chart results of their experiments with different baking soda/vinegar ratios.
•  Modeling the Chemical Reaction  Students are introduced to a model of the experiment and using a weighing scale, paper clips, meter stick and pieces of oaktag, confirm the proportions they found experimentally to best meet the challenge.

• Vinegar, baking soda
• Weighing scale, 100 ml graduated cylinders
• Ping-pong ball, meter stick
• Balloons, thermometer
• 1-meter tall plastic cylinder with an open end
• Stand and clamps to hold meter stick and cylinder
• Paper clips, scissors
• Oaktag paper or manila paper stock (from folders)
•    Baking Soda Teachers Materials (12 page)
DESIGNS II project was funded by NSF grant ESI-9730469. The authors are Philip Sadler, Harold Coyle, Cynthia Crockett, Kerry Rasmussen, and Francine Rogers. Copyright 2002 by The President and Fellows of Harvard College, used with permission.