Lava Lamp
What You'll Need
Directions
What
Happened?
-
Bottle of Water
-
Vegetable Oil
-
2 Alka-Seltzer Tablets
-
Food Coloring
GRADE
5-8
TIME
10 min
-
Remove the label from the bottle of water.
-
Pour out water in bottle until ¼ full. If you are starting with an empty bottle, fill it ¼ full with water.
-
Add a few drops of food coloring to the bottle.
-
Cap the bottle, and swirl until the food coloring and water are combined.
-
Remove cap, and add vegetable oil to the bottle. Stop filling when the oil reaches about ½ inch from the top.
-
Wait for the oil and water to settle and separate; this should take a few seconds.
-
While waiting, break 1 Alka-Seltzer tablet up into pieces that will fit through the bottle’s opening.
-
Remove the cap, and squeeze the bottle; this lets the air escape, so the pressure in the bottle does not build up too high.
-
While squeezing the bottle, add the Alka-Selzer pieces, and quickly screw the cap back on the bottle.
10. Watch as the dyed water begins to bubble up to the top like a lava lamp.
11. This reaction lasts a short amount of time, but you can repeat by redoing steps 7-10.​
Since oil is less dense than the water, it settled on top. When you put the seltzer tablet into the bottle, it began dissolving, which created a gas. This in turn formed bubbles of colored water, which floated towards the surface but didn’t interact with the oil. This is because of intermolecular polarity. Basically, water molecules don’t like to interact with oil molecules because they are not of the same type.