Dry Ice Boo Bubbles

This experiment is beyond cool.  We just did it at my friend's Halloween party, and I wasn't sure who was more fascinated - the kids or the adults.  Bubbles are cool in and of themselves.  But fog-filled bubbles that you can hold and bounce - well, that's just something else.  These bubbles form slowly, and literally in your hands!  Can you tell how excited I am about this?!  

Now, I've done this experiment with my own kids a few times over the summer.  We used a cut-up soda bottle and a funnel like I saw some people do online, and it worked just fine.  But I realized (translation:  learned the hard way) that this would work a lot better if the water and dry ice were in a sealed container.  So the week before my son's class Halloween party, I took a trip down to our local Do-It-Center, and figured out (translation:  asked the nice employee) what I need to build my very own sealed Boo Bubble generator.  I highly suggest you do the same as using a two liter unsealed bottle filled with water and dry ice around a bunch of kids is not a good idea.  Plus, the experiment works pretty much consistently using this method, as the gas rising up from the water has no where to escape except through the plastic tube.  

Ok, so here is your list of stuff to get from the hardware store.  If you don't have a heavy duty glove, you might want to pick one of those up while you're there (at the gardening section).  You'll need a heavy duty glove or a pair of tongs later to pick up the dry ice.

The clear adhesive is optional depending on the container you choose to use.  If you use a round container like me, you'll need it.  If your container has flat sides (see below), then you won't.  Same goes for the cork washers (#8).  You'll need them if you use a round container.  Otherwise, you can just get another pair of flat washers (#9).

Ok, so a couple of notes about the plastic container.  I actually had the one I used just sitting around at home.  It used to be an "I'm Bored" jar, but my kids got bored of using the "I'm Bored" jar...  My jar is made of some hard plastic, and I needed to (ask hubby to) drill a hole in it.  You can just as easily use one of the containers below (and you'll have an excuse to eat all those extra pretzels!)  Then, you can just use a utility blade to make the hole.  The one on the left is probably my favorite because it's nice and big, and it has a tight seal, and flat sides which make it easier to work with.  The one in the middle will work, but you might need to open it up more frequently to switch up the water (with warm water) and add more dry ice.  The one on the right will work although I'm a bit concerned about the seal not being tight enough.  And again you'll need the clear adhesive and some flexible washers.  

Ok, hopefully you had an easy enough trip to the hardware store.  I get intimidated by those places, but I try to remind myself that like everything else, the more you go, the more comfortable you'll feel...  

First thing you have to do is cut the top of your plastic cup, and make the hole in the bottom (#1 below).  The hole needs to be bigger than the hole inside your washers, and smaller than the washers themselves.  Place one washer and one PVC coupling on the inside of your cup above the hole (#2).  Place your forefinger through the PVC coupling, flip the cup over, and place another washer on top (#3).  Screw in one tubing adapter (#4).  Insert your plastic tubing inside your tubing adapter (#5), and repeat steps 2-5 with the hole you created in your plastic container (#6).  Because my container is round, I used the flexible cork washers and sealed with the clear adhesive this time, but otherwise the process is the same. 

And there you have it - your very own homemade Boo Bubble generator!  Isn't it cool?!  Ok, I'll let you make some fog-filled bubbles before you decide...

See below for what you need for the experiment.  To find dry ice in a store near you, you can use this dry ice directory.  Dry ice should be purchased right before you plan to use it as its temperature is cooler than the freezer's, and even in there it will last just a few hours before it evaporates.  Because of its extremely cold temperature, dry ice will burn the skin.  I use a hammer to break it, and a heavy duty glove to pick it up.  The kids are not allowed to get near it - not even with a heavy duty glove!  

Now either have another adult hold the generator while you do the experiment, or place the generator on a chair or a small table while you sit on the floor with the kids.  Fill the generator with warm water up to about an inch below the tube hole.  Using a heavy duty glove, pick 2-3 pieces of dry ice, and drop them in the water.  You should immediately see some fog produced (#1).  Quickly seal the container back up.  The smoke should now come pouring out of the tube (#2).

Dunk the plastic cup into the bubble solution (#3), and watch what happens!  When the bubble reaches the perfect size, gently shake it off of the plastic cup, and it will quickly fall to the ground.  If you place a towel on the ground and the distance to the ground is not too long, your bubble might not burst (#4).  A cloud of fog erupts from the bubble once it does burst, which is also very cool to watch.  

Have the kids wear a pair of knit gloves to be able to hold and bounce the bubbles.  This, in my opinion, is the coolest part - just be ready for a line of kids wanting to do this again and again!

How Does It Work?

How Did We Fill the Bubbles with Fog?

Dry ice is frozen carbon dioxide.  When you drop pieces of dry ice into water, a gas bubbles out of the water.  This gas is a combination of carbon dioxide gas and water vapor.  All the gas that's being built up is causing a lot of pressure inside our container, and the only way for this gas to get out is through the tube.  Since our tube is connected to a cup that's being dipped in a bubble solution, the flow of smoke coming out of the tube, fills up the bubbles.

How Did We Bounce the Bubbles?

A bubble's worst enemies are oil and dirt.  That's because the oil and dirt particles break down the soap film, and make the bubble pop.  But, if the bubble lands on a softer fabric that is free of oil and dirt, it won't break.  That is why you can bounce the bubbles using the knit gloves, and that is why the bubbles (sometimes!) don't pop when they land on a towel.

Ready for More?

Since I already have dry ice on hand, I like to combine this experiment with the Crystal Ball Bubble experiment.  This experiment is based on a similar concept, but it does not involve building your own generator (phew!), and you should be able to find all the rest of the materials around your house.  It involves a bubble which grows and grows out of a bowl, and stays around for at least 30 seconds before it bursts into a cloud of fog.  It gets so big, it ends up looking like a crystal ball.  So, head over to my Crystal Ball Bubble post if I've inspired your curiosity, and head over to my Halloween Science Party post for more Halloween science ideas.

I hope you had fun with this!  Please share your experiences!  

See you soon,