We worked through the remainder of the Lesson 8 worksheet today, tracing copper as it moved through the copper cycle and learning about the Law of Conservation of Mass in the Lesson 8 PowerPoint. We concluded the class with a demonstration. Most students were familiar with the chemical reaction of adding vinegar and baking soda together (it bubbles!). Students looked up the chemical formulas for both reagents and we discussed the products that are generated from combining the reactants (baking soda and vinegar). Students learned that the products of the reaction are sodium acetate, water, and carbon dioxide gas. The following question was posed: If a known amount of baking soda and vinegar were combined together in an open container on a scale, what would happen to the final mass of the products remaining in the container on the balance.
For the experiment, 5 grams of baking soda were added to 59.6 grams of household vinegar (5% acetic acid in water) in a flask placed on a digital balance. After a few minutes, the reactants stopped bubbling, and the mass of the remaining contents in the flask were found to be 57.5 grams. Therefore, the difference of 2.1 grams (59.6 grams minus 57.5 grams) should be the mass of the carbon dioxide gas released into the atmosphere. Tomorrow, students will conduct their own experiments and be tasked with using our available technology to evaluate the Law of Conservation of Mass for a given set of reactants.