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1. For lava lamps to work, the specific gravities of the water and wax need to be similar, calculate the specific gravity of the wax in the lamp. The density of paraffin wax is 900 kilograms per cubic metre. What is its specific gravity?
2. What causes the wax’s movement in the solution?

1. Who invented the lava lamp?
2. Why does the paraffin wax and water not mix together?

Answers

1. 900/1000 = 0.9
2. At room temperature, the wax should be marginally less dense than the medium it is in. When the lightbulb at the bottom of the lava lamp is switched on, the wax begins to heat up. Eventually, the density of the wax decreases to a point at which it becomes less dense than the salinated water it is surrounded by. At this point, the wax begins to rise. As the wax rises, it comes into contact with the cooler liquid at the top and transfers heat to it. The wax therefore cools and becomes denser, so sinks back down to the bottom of the lamp.
3. Edward Craven Walker

1. The wax and water do not mix as the wax is hydrophobic which means that the molecules of the paraffin wax are more strongly attracted to each other than a molecule of wax and a molecule of water.