The cabbage juice activity will show the students how different liquids alter the fundamental characteristics of others. By using acids and bases, you can significantly alter the color of cabbage juice. By placing the same amount of cabbage juice into two cups and then instructing the students to add a small amount of lemon juice to one and Alka Seltzer dissolved in water to the other, the students will learn the color change properties of the combination of different types of chemicals.
After explaining the process of evaporation, have the students perform an activity that evaporates the water from saltwater to form clean drinking water. Combining the salt in the fresh water to start will help the students understand the chemical reaction that creates saltwater. Model the proper way to set up the experiment by showing the students how to place the cup in the bowl, add the saltwater to the bowl and cover the top with plastic wrap. Adding the rock just above the collection cup will bring the water down toward the center of the bowl where it will drop down into the cup.
By combining steel wool and vinegar you can teach your students about chemical reactions. Observe as each group places steel wool in a jar. After adding enough vinegar to cover the steel wool, the students can set the jar aside until the next day. In order to get a chemical reaction, the students can then pour 1 tablespoon of the liquid from the jar into a new jar and also add 1 tablespoon of ammonia to the same jar. After stirring, a green blob will be created, signifying a chemical reaction between the two liquids.
Hydrogen peroxide is a common household product that can create an interesting chemical reaction in many instances. One way to teach the students about chemical reactions involving this chemical is to place a raw potato slice in a clear glass or beaker. After explaining that the inside of a potato is starch, add the hydrogen peroxide to the glass, covering the potato. Bubbles will start to form almost immediately and flow up to the surface, releasing gas. This action shows a chemical reaction between the starch and hydrogen peroxide that can be discussed in class with your students.