Objectives: Students will be introduced to the concept of energy conversion by observing the effects of vinegar and baking soda on raisins.
Materials: vinegar, baking soda, raisins, a clear glass, stop watch
- Fill a glass one-third full of vinegar and one-third full of water. Slowly add one teaspoon of baking soda to this mixture.
- Add 5 or 6 raisins to the glass. Ask students to observe what happens.
- Assist students in naming the phenomena that they are seeing.
- Have students generate a list of operational questions they would like to answer such as: What would happen if more vinegar were used? Less vinegar? More/less raisins?
- Let students investigate these questions, observing and recording data.
- Suggest graphing the independent vs. dependent variables as a way of recording their data. For example, if the amount of vinegar varies, the vinegar concentration would be the independent variable and the length of time that the raisins dance would be the dependent variable.
- Assist students in understanding the concept that energy can be changed from one form to another; in this experiment from chemical to mechanical.
- Students should be helped to understand the following questions: What type of energy is produced when baking soda is added to vinegar? What kind of energy is produced by this chemical reaction? What energy transfers are involved in this activity?
Closure: Discuss other kinds of energy your students have seen before. See if they are able to think of instances of energy transfer they have seen before?
Evaluation: Were students able to think of other instances of energy transfer? Did they grasp the basic concept?