In Part 1 of this experience, students worked with "Rising Raisins". There they found that bubbles prefer to form on a surface and just not come out of solution on their own. Here, we take that knowledge and attempt to get lots of bubbles to form in one small area to create a "Pop Bottle Fountain". For this, you will need a two liter bottle of seltzer water. Soda will work fine but it tends to make a sticky mess. Seltzer water will just evaporate leaving no sticky residue. As far as clean-up is concerned, seltzer water is the winner. You will also need a hammer, nail, a piece of string about two feet long, some tape, and a candy Menthos. Menthos are mint flavored chewy candies found in the grocery check-out. There are six or eight in a package. Have the students make observations about a Mentho. They will note that its white, smooth, and not round. Ask them to observe the shell more closely. It really isn't as smooth as it appears on first glance. What do you think will happen if we place this in seltzer water? Carefully remove the cap from the seltzer bottle. Some gas will escape. Don't worry. Place the cap on the sidewalk so that the top is facing up. In this way something could be hidden under it, but that's not what is going to happen. Using the hammer, pound the nail through the top of the cap to make a hole. You are done with the hammer and nail. Run the string through the hole so that the cap is halfway up the string. Attach one Mentho to the end of the string that is going into the cap. Use some tape to do this. This attachment will be flimsy at best. Draw the attached Mentho up into the bottle cap by pulling on the string that leaves the top of the cap. Screw the cap (with the Mentho inside) tightly onto the bottle. Do not let the Mentho touch the seltzer water. You're ready for the fountain. Make sure it is pointing at no one. Count down, "Three, two, one!", and pull the string. The Mentho will be freed from the string and tape and drop into the seltzer water. There, the Mentho will provide lots of surface for bubbles to form very quickly. The pressure will build inside the bottle and the water will spray from the bottle as a gorgeous, though short lived, fountain. Quite exciting, indeed. Did the students guess correctly? Next time, more science activities to try. Until then, have fun! |
