Here's a great experiment for the kids, but make sure they're not wearing their Sunday clothes when you try it.
*** WHAT DO I NEED? ***
- One 2-Liter Bottle of Soda
(Diet soda is recommended - less sticky!)
- A pack of Mentos
- Optional: A test tube and an index card
- A level surface, preferably OUTDOORS!
*** HOW DO I MAKE THIS WORK? ***
.....After you have gatherd the Mentos and soda, find a nice level spot outdoors. Keep in mind that the area around you (and quite possibly yourself) will get wet and sticky!
.....Open the 2-Liter bottle of soda and place it on a flat surface. If you have found a test tube, open the Mentos and place as many as possible inside the tube, making sure that they can easily slide out when the tube is tipped over.
.....Place the index card on the open side of the tube and turn the tube to face the bottle's open mouth. The only thing keeping the Mentos from falling into the bottle of soda is the thin index card.
.....When everyone is ready, pull the index card away and drop the Mentos into the bottle. If you do not have the test tube and index card, then you can try to feed them into the bottom using your hands.
.....Be ready! -- the soda will quickly react with the mentos causing a soda fountain SEVERAL METERS TALL!
*** WHY DOES THIS HAPPEN? ***
....Soda get its fizz from a gas known as carbon dioxide. When the carbon dioxide is pumped into the soda, water molecules cling to the gas and create tiny bubbles of gas in the liquid. The force holding the gas inside the water is known as surface tension.
.....It takes a lot of energy to break the surface tension inside soda, but most of you have probably done this by dropping a can and opening it shortly afterwards.
.....Mentos contains a chemical known as ARABIC GUM (this is the ingredient that makes the mint "chewy"). This ingredient causes the surface tension of the water molecules to break even more easily, releasing more carbon dioxide gas at an astounding rate!
.....The gas causes pressure to rapidly build inside the bottle which thrusts the soda upwards in a wonderful fountain-like BLAST!
.....As most know, like a melting popsicle, melted sugar is VERY STICKY! Try to use DIET soda (or any other carbonated beverage that does NOT contain sugar), otherwise you'll be running for the shower!