SET: Lava Lamp

Welcome to another edition of SET (Science Experiment Thursday)!  Today we are making some homemade lava lamps:

You will need:

-1 clear, plastic bottle
-Oil (we used canola oil) Actual measurements will depend on the size of bottle you are using
-Alka-Seltzer (you will use 1/2 a tablet at a time and you can repeat as many times as you want!)
-Food coloring of your choice (we did yellow because that's what Monkey J wanted, but since the oil was already yellow, we then chose red)
-Light/flashlight (optional)
-Glitter (optional)
-Funnel (optional)

First, fill the bottle 1/4 of the way full with water.  Then add oil until the bottle is almost full (might be best to use funnel here).  Wait for the water and oil to separate:

 Next, add the food coloring into the bottle and observe what happens:

Lastly, add 1/2 a table of Alka-Seltzer (here's where it starts to bubble!)

It's super cool!

And even better when we added in the red ;)

We then put a flashlight under the bottle and observed the lamp:

We repeated it over and over again simply by adding more tablets.  We even did two halves at once to watch what happened.  So how does it work?  The oil floats on top of the water because it is less dense than the water.  The food coloring and the water have the same density, so the food coloring falls through the oil and mixes with the water.  The tablet sinks all the way to the water because it is dense and as it dissolves it makes gas and carbon dioxide.  Gas floats to the top since it is less dense than the water and oil.  The air bubbles carry some of the colored water with them.  When the air bubble "pops" and the water comes out of it, the water falls back down to the bottom.  This reaction occurs over and over again until there is no more tablet left to dissolve.

So who loves science?!

We do!