Have You Ever Wondered How a Lava Lamp Works?

Lava LampCredit: Amazon


If you have a lava lamp, you may find yourself gazing at it and wondering, "What is the lava in a lava lamp?"  It actually is a rather interesting chemical reaction.  Once you understand how it works, you can even make your own lava lamp.  You just need two liquids that have similar densities, but won't mix together.

Two Insoluble Liquids

Have you ever tried to mix oil and water together?  You may be able to shake it and make it seem like it's mixed, but give it some time, and the two parts separate, no matter what you do.  This is why salad dressing often needs to be shaken up before you use it. Lava lamps are made using a similar concept.  You need two liquids that you can shake together, but never really combine.  The scientific term for this is the liquids are insoluble.

Slightly Different Density

But oil and water won't function as a lava lamp.  That is because water always sinks to the bottom, and oil rises to the top.  They do this fairly rapidly as well.  This is because the density of water is much greater than the density of oil.  That means that the molecules in water are closer together than the molecules in oil. so it's heavier.  Since they separate rapidly, their densities are too far apart.

In a lava lamp, you need two liquids that have similar densities so that your lava blobs move slowly.  If the density difference is two great, you'll lose the slow moving blob effect.  If the density is the same, your blobs won't move at all.

There are a lot of different liquid combinations that you can use in a lava lamp.  The most common in home made lamps is mineral oil and alcohol.  There are also methods[7593] that use antifreeze and dry cleaning chemicals, but I would not do that with kids.

And Add Heat

But even if you combine two nonsoluble liquids of slightly different density, you're not going to automatically make a lava lamp.  You'll just get two liquids that sit on top of each other without moving.  To make the lava come alive, you'll need to apply one special ingredient - heat.

When you add a low wattage bulb to the bottom of a lava lamp, you get a source of heat.  This heat causes the molecules in the slightly denser liquid to start vibrating a little faster.  As  they move faster, they start to spread out. This makes the liquid less dense than the top liquid.  So a blog will break off and start to float upwards in the glass container.  

As it rises away from the heat, it slowly cools back down.  This causes the molecules to move a little slower and closer together, increasing the density.  And so the blob sinks back down.

This all happens in slow motion, so you get the slow rising and falling of the blobs of one liquid in another.  And that is what makes it look like lava.


Modern Lava Lamps

Lava lamps haven't changes that much since they first became popular in the seventies.  Now you can find all sorts of different designs though, like twin lava lamps with two columns, metallic wavy lamps, and lamps in almost any color that you want. There's also some awesome ones with glitter that are worth checking out.

Popular Lava Lamp at Amazon

This model has the best reviews of all the lava lamps at Amazon. It looks nice, and it's not that expensive.

Would You Ever Make Your Own?

 So would you ever make your own lava lamp?  It's definitely not for everyone, especially since store bought lamps are so cheap.  However, it does make a fun science project, especially if you are learning about density of liquids.  You can also customize your own lamp much more than any store bought one.

All you need to know to make your own is what makes the lava in a lava lamp!  And the answer to that - well, it's up to you!