Using the evidence from an investigation, students propose explanations for why the balloon did not inflate when baking soda was added to water, but did inflate when baking soda and cream of tartar were added to water. Students compare data on the time required for a balloon to inflate, and explain why the balloon inflated faster when the amounts of baking soda and cream of tartar were doubled. Students also explain why yeast did not produce carbon dioxide when salt was substituted for sugar. Properties and Changes of Properties in Matter, Grades 5-8 A characteristic property of baking powder is that it produces carbon dioxide when dissolved in water. Substances react chemically in characteristic ways with other substances to form new substances with different characteristic properties.
Yeast releases carbon dioxide and water as it metabolizes sugar.
Chemical Reactions, Grades 9-12 Chemical reactions in living systems are catalyzed by protein molecules called enzymes. Yeast, a living organism, metabolizes sugar with the help of enzymes. Many important reactions involve the transfer of hydrogen ions between reacting molecules or atoms. Chemical reactions occur all around us, for example in cooking. Leavening agents such as baking soda, baking powder, and yeast release carbon dioxide in their chemical reactions, causing breads and cakes to rise as the gas becomes trapped in the food.