Yet another fun and exciting science experiment from our Fascinating Science for Kids eBook ! This post was inspired by The Recipe Room, Mom to 2 Posh Lil Divas, and Steve Spangler Science.

Just so you are not confused, this is not a real lava lamp…you can’t plug it into the wall or anything. But it does, however, imitate the look of a lava lamp! This makes for a great science activity for kids!

Related Post: 25 Awesome Science Fair Ideas For Kids

How To Make A Lava Lamp

Homemade Lava Lamp Supplies:

a 16 oz. or 1 liter bottle (we used a 2-liter and it used WAY too much oil)
vegetable oil (or whatever kind you have),
water
a funnel
food coloring
Alka-Seltzer tablets

*Alka-Seltzer tablets are considered medicine and contain aspirin. Do not let your child handle this medication.*

Step By Step Lava Lamp Instructions:

STEP 1. Fill your plastic bottle half-full with oil. This is why I suggest using a smaller bottle…we used over half a bottle of oil with this experiment alone!

STEP 2. Fill the remaining half of the bottle with water. Have your children watch as the water separates and slowly sinks to the bottom (because the water is heavier).

STEP 3. Add 10 drops of food coloring. Make sure to use only 1 color.

STEP 4. Cut one Alka-Seltzer tablets into fourths. Again, do not let a child handle the Alka-Seltzer tablet as it is medication.

STEP 5. Drop one of the pieces of Alka-Seltzer into the top of the bottle and watch what happens!

To get the “lava-lamp” effect, you’ll need to add another fourth of Alka-Seltzer every 30 seconds or so.

The Science Behind This Lava Lamp Experiment:

Oil and Water

Both the water and the food coloring sink to the bottom of the bottle while the oil floats at the top because water is heavier than oil. The food coloring dissolves in the water but not in the oil.

How does Alka Seltzer work?

When you drop the piece of Alka-Seltzer into the bottle, it reacts with the water and creates carbon dioxide gas bubbles. Because the food coloring has already dissolved into the water, the bubbles are “colored” and float to the top! Once they ‘pop’, the colored bubbles sink back to the bottom of the bottle.

This post was first published May, 2012. Last updated 2018.

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Click here for more fun science activities for kids…

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12 Comments

I have been meaning to do this with my daughter but never remember to buy Alka-Seltzer. It definitely looks like fun!

Vicki says:

February 10, 2016 at 8:16 pm

You can do this with regular table salt… Fill bottle 3/4 water, add a few drops of color and fill the bottle with oil but leave about 1 inch at the top. Let children add salt with a spoon and watch the fun. Hope you enjoy :) Also, it’s easier if you use a tall skinny glass instead of a bottle…..

Reply

THis is totally on list for summer. Thanks for sharing.

I tried to download the free Science Book but it takes me to the page where you subscribed to the blog which I have been for many months now. What am I doing wrong? Thanks for all your great information and inspiration. You are a great mom. Your kids are lucky to have you,

We just did this experiment today. Definitely use a smaller water bottle to save on oil. I didn’t realize you had to keep adding the tablets to get the bubbles moving. We will be keeping this experiment outside on the picnic table. Thanks.