Bubbling+Lava+Lamp

__ Bubbling Lava Lamp __

Kaari Casey e-mail: kec232@psu.edu Terri Mercer e-mail: tmm5246@psu.edu

This lesson is designed for students grades 5-7 and focuses on properties of non-polar and polar molecules when mixing oil and water. The Pennsylvania State Standards that will be addressed are 3.2.7 B ("Apply process knowledge to make and interpret observations"), 3.4.7 A ("Describe concepts about the structure and properties of matter"), and 3.2.7 B ("Apply process knowledge to make and interpret observation").

Objectives : 1. Students will be able to define polar and non-polar molecules. 2. Students will be able to explain how molecular interactions cause separation and why. 3. Students will be able to identify properties of different molecules, including density. 4. Students will be able to justify their observations with scientific knowledge.

Content Explanation : "The polar molecules of water do not like to mix with the nonpolar molecules of oil. Because oil is less dense than water it floats to the top of the bottle. Even if you shake up the bottle, the oil breaks up into small little drops, but the oil still doesn't mix with the water. Also, the polar food coloring molecules only mix with water; they do not color the oil. The Alka-Seltzer tablet reacts with the water to make tiny bubbles of CO2 gas. These bubbles attach themselves to the blobs of colored water and cause them to float to the surface because they are momentarily less dense than the oil. When the bubbles pop, the color blobs sink back to the bottom of the bottle. The phenomenon is due to the polar and non-polar/hydrophilic and hydrophobic interactions of the molecules."

Materials, Equipment, Set-Up: • 16 oz. empty soda bottles • Vegetable oil • Water • Alka seltzer tablets • Funnels • Water containers • Food coloring • Glitter/sequins/beads

Activity : SAFETY : Swallowing materials Body of Lesson a) Predict: (3-5 Minutes) a. Hey guys! My name is ___, what are your names? What do you know about lava lamps? How do you think they work/what are they made of? (Question them according to how much they know)  b. Today we are going to be making our own bubbling lava lamps.  c. What is the difference between the oil and the water? What do you think will happen when we mix them? Then mixing them in the demonstration container, show them how they don't mix. Why don't you think they mix? Is there anything we can do to get them to mix together?  d. Ask students what they know about Alka-Seltzer or bubbles in soda. If we drop Alka-Seltzer in pure oil will it bubble? What will happen when we drop Alka-Seltzer into water?  e. Will food coloring color the oil? Will food coloring color the water? Why/why not?

b) Observe: (10 minutes) a. Drop the Alka-Seltzer in the separate oil and water containers. Why does one bubble and one stay still?  b. Then add food coloring to each container (observe how water colors and oil does not).  c. How do we make our own lava lamp and how does it work? Fill empty soda bottle ¾ of the way with vegetable oil. Fill the remaining ¼ with water. Add 10 drops of food dye. Add Alka-Seltzer tables so that the lava lamp begins working.  d. Give the students the supplies to create their own. Adding glitter and questioning them along the way to guide them through the experiment.

c) Explain: (7 minutes) a. After/while the students create their own, explain the properties of polar and non-polar molecules of the water and oil. Add the concept of "likes dissolve likes" and why the food coloring only dyes the water and not the oil.  b. Discuss the concept of density, and why oil floats on water.  c. Discuss the properties of CO2 gas bubbles and how they capture the food colored water blobs and cause them to float to the surface due to reduced density.  d. Ask the students if other material wouldn't mix as well. Have them reiterate the concepts previously explained. Ask them how they would explain how their lava lamp works to other students. Allow them to bring them home.  e. If there is extra time, we can discuss the oil spill in the Gulf and the properties of the oil and water mixture. We could also discuss the concept of coating on feathers to make some birds seem water-proof.

References : Steve Spangler Science. "Make Your Own Bubbling Lava Lamp." 2011. .