Yet another fun and exciting experiment from our Fascinating Science for Kids eBook (get yours now…it’s currently free)! 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!
Here’s what you’ll need: 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, and Alka-Seltzer tablets.
*Alka-Seltzer tablets are considered medicine and contain aspirin. Do not let your child handle this medication.*
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!
2. Fill the remaining half with water. Have your children watch as the water separates and slowly sinks to the bottom (because it is heavier than the oil).
3. Add 10 drops of food coloring (use only 1 color).
4. Cut one Alka-Seltzer tablets into fourths. Again, do not let a child handle the Alka-Seltzer tablet as it is medication.
5. Drop a fourth of the piece of Alka-Seltzer into the top of the bottle and watch what happens!
6. To get the “lava-lamp” effect, you’ll need to add another fourth of Alka-Seltzer every 30 seconds or so.
The Science Behind It:
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. 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.
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