Science Sunday - Fun With Oil, Water and Alka-Seltzer?

We attempted a homemade lava lamp, using the classic oil/water/food coloring combination, but with the addition of some fizz a la Alka-Seltzer.

We started with a water bottle filled 1/3 full with water, and topped with 2/3 vegetable oil. I'm pretty sure for the lava lamp effect, less water would work better, but I'll get to that in a minute.

Water, and oil don't mix, and water is denser than oil, so it sinks to the bottom. Once everything had settled, we added a few drops of water soluble food coloring.

The food coloring will not dissolve into the oil, but instead, forms balls, and falls through it. The colored balls sit for a few seconds, where the water and oil meet. Until at last, they break through the oil barrier, and mix with the water. We've done this before, as fireworks in a jar.

This time though, we continued on. Once all the color had broken through into the water, we added a couple broken Alka-Seltzer tablets. The fizzing bubbles produced by the Alka-Seltzer picked up some of the color, and carried it back up through the oil. Then, once the air bubbles popped at the top, the color droplets fell back down, to start the journey over again.

We had planned on shining a light up through the bottom of the bottle, for a lava lamp effect, but our colored water layer was too thick, and dark, and didn't let enough light through to make it interesting, even in a dark room.

It was fun however, to sit and watch the color droplets rising, and falling.

When the fizzing slowed, we added more Alka-Seltzer, to start things back up again. I had actually been planning on keeping the bottle full for a few days for the children to play with some more, but someone decided it would be fun to watch cookie pieces ride the bubbles too, so in the end, we had to dump the whole thing out.

At least, the bottle didn't get knocked over, which is what the man of the house was betting on. Or, maybe that was a scientific prediction, based on previous observations.

For more fun with science, check out this week's Science Sunday link up, at Adventures in Mommydom.

It's great to be a homeschooler.