Balloon On A Stick: Difference between revisions

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== Age ==
{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Chemistry]]:
| Polymers
|-
| Grade Range:
| [[Elementary School]], [[Middle School]]
|-
| Format:
| [[Hands-on]]
|}


Elementary School, Middle School, High School
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!
 
== Format ==
 
Hands-on


== Materials ==
== Materials ==


    Round balloons (at least two for each time you do the demo)
* Latex Balloons
    Wooden skewer
* Petroleum Jelly
    Hand lotion
* Skewers
* Optional: Heavy Duty Scissors


== Safety Precautions ==
== Safety Precautions ==


Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience. Skewers are sharp. Balloon pieces might fly through the air. Use general precaution.
Please read the General Safety section of the [[Demonstration Safety]] page before performing this demonstration.


== Preparation ==
It’s best to blow up a bunch of balloons before the demonstration.


== Demonstration ==
== Demonstration ==


1. Put some hand lotion on the entire length of the wooden skewer (this just reduces the friction and allows the skewer to slide though the balloon.
# 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.
2. Show the kids the sharp skewer, and the balloon. Ask them to hypothesize what will happen if you poke the balloon with the stick. (you may need to explain that hypothesize is a science word for “take your best guess”)
# 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.
3. Pop the balloon by sticking the stick into it horizontally. (Hold the balloon at the bottom by the tie, insert stick perpendicular to the tie.) The balloon should pop.
# Optional: Before giving the balloon to the student, you may use the scissors to cut off the tip of the skewer.
 
4. Now take another balloon and show them the bottom. Is there anything different (there is a bump, it is darker in color, etc) What are balloons made of? (latex, a kind of rubber. Explain why the balloon is darker in that area. (the polymer is less stretched out, you can demonstrate the difference using an uninflated balloon, showing stretched and not stretched)
 
5. Have the kids guess again if you will be able to stick the skewer through the balloon, this time through the other side, where the rubber is darker and out through the side that has the tie on it.
 
6. Gently but firmly insert the skewer into the balloon. It takes a little bit of twisting and is a good idea to practice before you do the demo.
 
7. Ask the kids why it worked, and if they have any questions! This is science that you CAN do at home!


== What to Say ==


Read through the [[#Demonstration]]. What to say is within.
== Why This Works ==


== Why It Is ==
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!


Balloons are made of latex, a polymer made of molecule strands that are all tangled together (think spaghetti). Bonds between the strands, called cross-links give it its elastomeric properties. (You can stretch it to a certain point without breaking it.) The molecules on the sides of the balloon are already very stretched, and break much easier than those on the top or bottom of the balloon.
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!


== Real Life Examples ==
== Additional Information ==


Elastomers are used for a variety of products, including balloons, bouncy balls, and rubberbands.
* This demonstration pairs well with the [[Polymer Milk Jug]]

Latest revision as of 15:07, 5 April 2016

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

  1. 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.
  2. 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.
  3. 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!
  4. 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.
  5. 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