This Leak-Proof Bag Experiment will amaze your kids, and probably even have you scratching your head trying to figure out why a plastic bag poked with sharp skewers doesn’t leak water everywhere!
Discover more Fun Water Experiments here!
The good news is, we are going to show you exactly how to do this super cool experiment and then explain the science behind it too!
Leak-Proof Bag Experiment
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How do You Make a Leak-Proof Bag?
- Fill a plastic Ziplock bag about 3/4 full with water.
- Stick a few sharp skewers through the bag one by one.
- Watch in amazement as your punctured bag does not leak!
- Slowly pull the skewers or pencils out of the bag to see what happens!
Step 1: Pour Water Into a Plastic Bag
I prefer to use quart size storage bags for this fun experiment, but you can use any size bag as long as they have a zipper at the top to seal them.
Unzip the top of your bag while using one hand to hold the bag open, and another hand to pour some water into the bag.
Fill the bag about 3/4 of the way full of water and then seal the bag by zipping the top closed.
Step 2: Poke 5 or 6 Sharp Skewers Into the Bag
There are a few different household items that you can use to poke holes through your plastic bag. Whether you choose to use wood skewers, metal skewers, or well-sharpened pencils this experiment will work the same.
I used a handful of 12-inch long wood skewers since that is what I could find around the house and they worked great!
Go ahead and grab one skewer at a time and gently push them all the way through one side of the bag and out the other while leaving them poking out of both sides of the bag.
Repeat this process with as many skewers as you want while pushing them through the bag from all sorts of different angles and levels.
Step 3: Spin the Bag Around and Check For Leaks
When you are satisfied with the number of sharp objects piercing through your plastic bag, slowly turn your bag around while holding it with one hand from the top of the bag.
Inspect the bag for leaks and enjoy being amazed at what you see!
Don’t be surprised if you see a drop or two of water near the holes in the bag. These likely formed when you initially poked the bag, but now that the skewers are through the holes there should be no leaks!
If you think this experiment is pretty cool, you might also like this Unpoppable Balloon Experiment when we pushed a skewer through an inflated balloon without it popping!
Step 4: Pull the Skewers Out to See What Happens
After you have taken some time to admire your work in creating your leak-proof bag experiment, try pulling a few of the skewers out of the bag to see what happens!
Do you think the water will continue to stay inside the bag without spraying out of the holes when the skewer is removed?
You probably guessed that the water will leak out of the holes once the skewers are pulled out and you were right!
Now let’s dive into the science behind why the bag didn’t leak when the skewers were going through it!
How Does The Leak-Proof Bag Work?
Many of you were probably surprised to see the plastic bag did not leak when sharp objects were poked through it…I know I was!
The reason the ziplock bag full of water doesn’t leak is thanks to something called polymers. Polymers are long, flexible chains of molecules that make up the material of the plastic bag.
When a skewer or sharp object pokes a hole in the bag, the long, flexible chains of molecules spread apart to make room for the skewer and then they shrink back together around the skewer to seal the hole in the bag.
When the skewers are pulled out of the bag, the flexible polymer molecules are not able to connect back together enough to seal the larger holes, and the water leaks out of the bag!
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