Balloon On A Stick
| Chemistry: | Polymers |
| Grade Range: | Elementary School, Middle School |
| Format: | Hands-on |
A kid-favorite for science fairs, this demonstration is a great way for kids to learn about polymers. They will all enjoy the chance to take a skewered balloon home with them too!
Materials
- Latex Balloons
- Petroleum Jelly
- Skewers
- Optional: Heavy Duty Scissors
Safety Precautions
Please read the General Safety section of the Demonstration Safety page before performing this demonstration.
Demonstration
- Tell the student that you are going to put a balloon on a skewer. If they are old enough (at least 3rd or 4th grade) you can ask them to blow up and tie a balloon for you.
- Put a small amount of petroleum jelly on a finger, and apply it to the top of the balloon (the darkest spot) and the bottom near the knot. Then, make sure the tip of the skewer gets some on it as well.
- Start at the base of the balloon, and slowly push the point of the skewer into the balloon. If it has trouble going through, gently spinning the skewer while pushing will help. The skewer will go into the balloon without it popping!
- Slide the skewer through the balloon, and copy your technique to get it through the top of the balloon. Make sure to push it through the darkest spot in the top, otherwise it might pop! The student can take the balloon with them if they would like.
- Optional: Before giving the balloon to the student, you may use the scissors to cut off the tip of the skewer.
Why This Works
Latex is a plastic material, and like most plastics it is a Polymer. Polymers are materials that consist of long strands of repeating molecules. The molecules are all linked end to end, and they can often stretch and move to let the material change shape and absorb hits without breaking. The polymer that makes up latex is very elastic, so we would call it an Elastomer, or elastic polymer. This is why we can blow a lot of air into a balloon, and it will stretch and expand a LOT before it pops!
In this demonstration we are taking advantage of this elastomer when we slide the skewer through it. The Latex does not want to break, and will stretch as much as it needs to in order to avoid popping. After we apply the petroleum jelly to help the skewer slide more smoothly, we were able to push it through the balloon because the Elastomer stretched around it! We did make a hole, but the hole is actually much smaller than the skewer, and it stretched open to let it slide through, and avoid popping the balloon!
Additional Information
- This demonstration pairs well with the Polymer Milk Jug