How Do Lava Lamps Work?

What is a Lava Lamp Really? Lava lamps, for our purposes, are containers with a mixture of immiscible liquids One liquid rises in blobs giving the appearance of lava kinetics

What? “Immiscible” - two things that don’t mix together (e.g., oil and water) Surprising that the substances don’t mix because they are both liquids Phases, intermolecular forces

What Does This Have to Do with Lava Lamps? The lava lamp I will demonstrate is made of oil, water, and Alka- Seltzer To understand why lava lamps are made of these ingredients let’s take a closer look at each one

Oil Oil molecules form an “induced dipole induced dipole interactions” The interactions between the molecules aren’t that strong Oil is hydrophobic

Water Water molecules interact through dipoles Water is hydrophilic This makes water a tetrahedral Lewis dot diagram, vsepr

Alka-Seltzer Alka-Seltzer releases CO2 The CO2 makes the water float reaction

This is like… Vinegar and baking soda experiment H-Ac + NaHCO3 --> Na+ & Ac- & H2O & CO2 (gas) Both reactions release CO2

Heat versus Alka-Seltzer Alka-Seltzer replaces heat used in traditional lava lamps Heat makes the molecules move faster The faster they move, the size is increased, but the mass stays the same Density is lowered, causing molecules to float

Put It Together The water sinks and the oil floats When the CO2 attaches to the H2O it makes the water float When the water reaches the top, the CO2 goes into the air and the water sinks back down

Which One Would You Choose? Oil Molecule Water Molecule

In Chemistry Terms Water can bond with oil but doesn’t want to This is because the dipole dipole interaction of the water is stronger than the dipole induced dipole of the oil and water This keeps the water moving because none of the water wants to be stuck next to the oil