After reviewing the homework problems assigned for Lesson 7, students were reintroduced to the Copper Cycle. Because the Copper Cycle experiment involves steps that must be conducted in a fume hood, we opted to watch a video (below), with students taking observations on their Copper Cycle handout. For reference, students also received a copy of the Copper Cycle experimental procedure.
After the video, we discussed the concept of Conservation of Matter, transitioning to Lesson 8 in the textbook. Because Lesson 8 continues an investigation of the Copper Cycle, and we are unable to safely conduct that lab, we instead investigated the related concept of Conservation of Mass. Students participated in a classroom demonstration which involved combining baking soda and vinegar in a closed system and experimentally demonstrating that mass is conserved. We measured the starting and ending mass, noting the slight decrease in mass at the end due to experimental error (vinegar and carbon dioxide leaking slightly). At the end of the experiment, we removed the inflated balloon and noted a decrease in mass of 0.2-0.3 grams, indicating the carbon dioxide gas has a measurable mass. Students also noted the change in volume of the products as evidenced by the partially inflated balloon compared with the volume of the reactants.
For homework, students were provided with a copy of the Penny Lab to read over in advance of Wednesday’s class. Students were also reminded that a signed syllabus and safety contract must be turned in to enable participation in the lab.