Soda Pop and Sweet Thing Geyser
- Full 2 Liter Bottle of Coca-Cola
- Masking Tape
- Dental Floss
- 3/4" 5d Finishing Nail
- Pack of Mentos Candy
- A Drill with a 1/4" Drill Bit
Remove the plastic insert from the plastic bottle cap. With the help of a parent, drill a 1/4" hole throught the center of the plastic cap. Using the nail, punch a hole through the center of six Mentos candies. Try not to crack the hard candy coating. Thread one end of the dental floss through the first Mentos candy and tie the dental floss to itself with two knots. Thread the free end of the dental floss through the remaining 5 Mentos so they hang as beads. Thread the free end of the dental floss through the hole dreilled in the bottle cap, pull the floss taut and drape it over the outer end of the bottle cap. Tape the floss onto the cap. Set the Coca-Cola bottle on a flat surface outside. Gently insert the Mentos into the neck of the bottle and screw the cap securely in place. Remove the tape and allow the Mentos to drop into the Coca-Cola and step back...
What's going on?
Coca-Cola will shoot from the hole in the bottle cap creating a geyser. Water resists the expansion of Carbon Dioxide bubbles because water molecules attract each other strongly. They link together to form a tight mesh around each bubble. Mentos are basically a big pellet of sugar with gummy stuff added t give them structure. It is the gelatin and gum arabic from the dissolving Mentos that disrupt that water mesh. It takes less work to expand the bubbles. Little nooks in the candy allow new bubbles to form quickly. As more of teh surface dissolves the process accelerates and foam rapidly forms. A similar process occurs when Root Beer is poured over ice cream for a Root Beer Float. Watch out for the outgassing of Carbon Dioxide!