This week, the chemistry students completed a reactions and observations lab. They observed physical and chemical changes during a complex chemical reaction. They also designed reactions and experiments to determine which chemicals are involved in each physical/chemical change.
Students were told that when 3 substances--calcium chloride (a solid), sodium bicarbonate (a solid), and a solution of phenol red (a liquid) are mixed together, a complex series of reactions occur.
For this lab, the students made observations of the reactants physical properties such as color, odor, state of matter, etc. and recorded them in a data table.
Then, they opened their zip lock bags and adds a small amount of sodium bicarbonate and calcium chloride to the bottom two corners of the bag, carefully making sure the two do not mix. Next, they used a transfer pipet to place a small amount of phenol red near the front of the bag and squeezed out the air to close the bag.
After gently combining the two solids with the phenol red, they observed what happened and recorded it. Their job was to figure out which reactants were responsible for the changes they observed. They completed the lab again to determine this.
These observations and experiments allowed students to process and discover physical and chemical reactions through the scientific method.