Justin+Experiments

Justin Hofmann Skewer through Balloon Materials - Several latex balloons (9 inch size works well) - Bamboo cooking skewers (approximately 10 inches long) - Cooking oil - Nerves of steel  Procedure: 1. The first step is to inflate the balloon until it’s nearly full size and then let about a third of the air out. Tie a knot in the end of the balloon. 2. If you carefully examine the balloon you’ll notice a thick area of rubber at both ends of the balloon (where you tied the knot and the opposite end). This is where you will pierce the balloon with the skewer … but not yet. Keep reading. 3. Dip the tip of the wooden skewer into the cooking oil, which works as a lubricant. 4. Place the sharpened tip of the skewer on the thick end of the balloon and push the skewer into the balloon. Be careful not to jab yourself or the balloon with the skewer. Just use gentle pressure (and maybe a little twisting motion) to puncture the balloon. 5. Push the skewer all the way through the balloon until the tip of the skewer touches the opposite end of the balloon where you’ll find the other thick portion of the balloon. Keep pushing until the skewer penetrates the rubber. Breathe a huge sigh of relief and take a bow! Ta-Dah! 6. <span style="color: #333333; font-family: 'Lucida Sans','sans-serif'; font-size: 9pt; mso-bidi-font-family: 'Lucida Sans'; mso-fareast-font-family: 'Times New Roman';">Gently remove the skewer from the balloon. Of course, the air will leak out of the balloon, but the balloon didn’t pop. Cool fact: There is a rubber tree in which the sap that comes from this tree is a natural source of rubber. <span style="font-family: 'Segoe UI','sans-serif'; font-size: 9pt; line-height: 115%;">[] Practical Uses <span style="color: black; font-family: 'Segoe UI','sans-serif'; font-size: 9pt; line-height: 115%;">: -Rubber Bands <span style="mso-ascii-font-family: Calibri; mso-bidi-font-family: 'Times New Roman'; mso-fareast-font-family: Calibri; mso-hansi-font-family: Calibri;">-Latex Gloves -Tires -Kickball -Rubber eraser Explanation : The skewer through balloon experiment is a great way to see how polymer chains cause a balloon to be stretchy. In this experiment all that was needed were a balloon and a wooden skewer. Whenever you blow up a balloon you notice that most of the balloon becomes clear while at the ends it stays darker. This shows how much stress the balloon is under. The clear area is under a lot of stress while the darker areas are under very little stretch. These dark areas are what enable the experiment to work. The whole balloon contains long molecule chains called polymers. Since these polymers are elastic, it causes the rubber to become stretchy. First if you were to try to poke the skewer through the clear part it would pop because the polymers can’t stretch anymore. But if you poke it through the dark part, there is more room for the balloon to stretch. When it is pokes through this spot the long strands of polymers stretch around the skewer to keep the air from leaking out, and this is what makes the experiment work.

In our current unit, petroleum, we did a similar lab to show how the same technique works. The lab included a plastic bag filled with water and about five pencils. Then the person holding the plastic bag would slowly poke the pencils through the bag filled with water. Since the bag was able to stretch and had little stress, no water leaked out. This is because the bag stretched around the pencil creating a seal. If pressure were to be applied to the plastic, it would cause stress and water would leak out. The same would happen with the balloon but instead of water, air would leak out. Last the polymer contains covalent bond which is the combination of two non-metals. Polymers are used mostly in plastics, petroleum, and are used in synthetic materials. Photos : Sources : <span style="font-family: 'Segoe UI',sans-serif;"> <span style="font-family: 'Times New Roman',Times; font-size: 16px; line-height: 32px;"> "Ficus, Rubber Tree, Rubber Plant, India Rubber Tree, Ficus elastica." //Master Gardener - Tropical Plants Library Online//. Web. 18 Feb. 2010. <http://mgonline.com/articles/rubber.aspx>."Skewer Through Balloon at Steve Spangler Science." //Science Projects Experiments, Educational Toys & Science Toys//. Web. 17 Feb. 2010. <http://www.stevespanglerscience.com/experiment/00000135>