Science Experiment: Lava Lamp Reactions!

Grace and Jack each filled an empty water bottle 3/4 full of vegetable oil. Next, they added water to fill up the rest of their bottles. It was a fun learning experience for Grace and Jack to see what happened once the water was added -- the water and oil did not mix together. Grace and Jack then added about 10-15 drops of food coloring to their oil and water mixture. They each chose their favorite color, purple for Grace and green for Jack. This step of the process was also very fun to observe. Finally, Grace and Jack were given Alka-Seltzer tablets, which I broke into several tiny pieces. They each dropped the Alka-Seltzer pieces into their bottles and were amazed with the reaction...and what a reaction it was! Grace and Jack absolutely loved this science experiment. They ended up using an entire box of Alka-Seltzer tablets. This is definitely an experiment we will be doing over and over again! How did this work? Here is how I described the experiment to Grace and Jack to help them understand the process:

Oil and water do not mix. The molecules of water do not like to mix with the molecules of oil. Even if you try to shake up the bottle, the oil breaks up into small little drops, but the oil doesn’t mix with the water. Also, food coloring only mixes with water. It does not color the oil. When you pour the water into the bottle with the oil, the water sinks to the bottom and the oil floats to the top. Oil floats on the surface because water is heavier than oil. The Alka-Seltzer tablet reacts with the water to make tiny bubbles of carbon dioxide gas. These bubbles attach themselves to the blobs of colored water and cause them to float to the surface. When the bubbles pop, the color blobs sink back to the bottom of the bottle!