At Home With Hands On!

Chilling Science with Dry Ice (10/4/17)

Caution: Dry Ice is an extremely cold substance which can cause harm if used improperly. You should always ask for adult assistance when using Dry Ice, and be sure to wear protective goggles and insulated gloves!!

dry ice tools

Self Inflating Balloon:

MATERIALS:

  • Balloon
  • Sharpie (Optional)
  • **Dry Ice**
  • Leather Gloves (or other thermal-insulating gloves)
  • Eye Goggles
  • Hammer or Mallet
  • Funnel
  • Salad tongs
  • Adult Assistant
  • Friends to play “Cold Potato”

INSTRUCTIONS:

dry ice balloon inflating
  1. (Optional) Inflate the balloon but do not tie it closed. While pinching the balloon shut, you can draw a design, a picture, or even a face (like a Jack-o-Lantern face!) on the inflated balloon using a permanent marker. Let the balloon deflate and allow the marker ink to dry for about 90 seconds.
  2. Insert the neck of a funnel into the opening of the balloon.
  3. Ask an adult assistant to break apart some dry ice into small, pea-sized pieces using a hammer or mallet (and remember to wear your protective goggles and gloves!).
  4. Using a pair of salad tongs or a spoon, place 10-15 small pieces of dry ice into the funnel, and push down the dry ice into the balloon.
  5. Tie off the balloon (without inflating it!).
  6. Hold and shake the balloon in your hands for a few seconds, then pass it to a friend to hold for a few seconds. You can play a very chilling game of “Cold Potato” as the Dry Ice inside of the balloon starts to warm up and seemingly disappear.
  7. Continue to shake and pass the balloon around until you cannot hear any pieces of dry ice moving inside of the balloon. What has happened to the Dry Ice inside the balloon? Have you observed any changes to the balloon itself? How might this change have happened to a sealed balloon?

HOW DOES IT WORK:

Dry Ice is the solid form of Carbon Dioxide (CO2), which we know as a gas at regular temperatures. Amazingly, Dry Ice can only remain solid in very cold temperatures (at least 109 degrees below zero!!!). At everyday room temperature, the Dry Ice does not melt into a liquid like water ice; instead, Dry Ice sublimates, which means that it turns directly from a solid into a gas!

The molecules that make up a solid material are much more densely (or tightly) packed together than the molecules of the same material in its gaseous form. When we place the solid carbon dioxide (the Dry Ice) into the deflated balloon, we are inserting a large amount of CO2 molecules that are very tightly packed together but don’t take up much room inside of the balloon. As the Dry Ice is warmed by the heat of your hands, the solid CO2 will sublimate into carbon dioxide gas. Although there is always the same number of molecules of carbon dioxide in the balloon, the gaseous CO2 takes up WAY more room (it has a greater volume). This causes the balloon to inflate from the inside!

Tank of Frightfully Fun Tricks (Three Tricks in One Treat!)

 MATERIALS:

  • Small Fish Tank
  • Water
  • **Dry Ice**
  • Bubble solution
  • Bubble wand
  • Large plastic mixing bowl
  • Shoelace or long strip of fabric
  • Beverage Pitcher or Measuring Cup with a spout
  • Candles and matches
  • Adult Assistant

INSTRUCTIONS:

  1. Fill a small fish tank to about 4 inches of room-temperature water.
  2. Ask an adult assistant to add 2-3 large pieces of Dry Ice to the tank of water (using insulated gloves and goggles!), and allow the Dry Ice to bubble for 10 minutes.
  3. Using the bubble wand, blow a number of bubbles into and around the Dry Ice tank. Do you notice a difference in how the bubbles act when they float into the tank? What might cause them to act this way?
  4. Light one or more candles and set them in a row on a clear, flat surface.
  5. Using the beverage pitcher or a measuring cup, scoop up some air from around the room. Reach up high and down low to fill the container with air! Slowly pour the air over the candles, watching for any change in the candles.
  6. Again using the beverage pitcher or measuring cup, scoop up some air from inside of the Dry Ice tank. Scoop air as far down as possible, without actually scooping any of the water at the bottom. Again, pour this air over the candles. Do you notice a change this time? Why might the air inside of the tank be different from the rest of the air in the room, and why might it affect the candle flames?dry ice and candles
  7. Fill a large plastic bowl (or other wide-mouth container) ¾ full of warm water. Ask an adult assistant to add 1-2 large pieces of Dry Ice to the bowl (using insulated gloves and goggles!). Now wouldn’t THAT look awesome as a Halloween decoration?!?!
  8. Thoroughly soak a shoelace or a thin piece of fabric in a bowl full of bubble solution.
  9. Using your finger, coat the rim of the plastic bowl with a layer of bubble solution.
  10. Hold the bubble-soaked straight taught and run it across the surface of the bowl. Make sure the string touches both sides of the bowl as you drag the string from one end of the bowl to the other. You should see a bubble film forming on the bowl’s surface. Be patient if the bubble film doesn’t form on your first attempt! Keep trying until you get it just right!
  11. Once the bubble surface has formed, sit back and watch as a mega-bubble grows from the container! Be extra observant of the moment the bubble eventually pops! What happens to the cloudy air inside of the bubble? Does it rise upward or does it fall downward?
dry ice bubble inflate

HOW DOES IT WORK?:

Why do the bubbles float inside the tank? The carbon dioxide (CO2) gas that is formed from the sublimation of the Dry Ice is actually heavier than your breath that is filling the bubbles. The lighter bubbles are buoyant (able to float) on the surface of the heavier CO2 gas layer—even though you cannot see the invisible carbon dioxide!

Why do the candles go out when you pour the tank-air over them? While the air inside of the tank will get a bit cooler due to the very cold Dry Ice, the temperature is actually not the reason why the candles are extinguished. Also, the air pouring from the container is definitely not moving fast enough to “blow out” the candles. Fire needs 3 things to burn: a source of heat for ignition, fuel to burn, and oxygen to feed the flame. When the dense carbon dioxide pours out of the pitcher, it acts much like an invisible liquid that pushes away the oxygen around the candle flames. Without its constant oxygen source, the fire quickly goes out.

Why does the mega-bubble grow without having to blow it up? Much like the Self-Inflating Balloon experiment, the sublimating Dry Ice becomes CO2 gas. The gas is far less dense than the Dry Ice, and takes up a lot more space. The bubble solution film acts as a stretchy lid that will contain the sublimating CO2 gas inside the bowl, but is still able to grow quite large as the expansive gas is pushes outward from inside. When the bubble finally bursts, the misty air flows downward because it is cooler and more dense than the air around it…and so it sinks!

THE MORE YOU KNOW

Since its discovery in 1835 by the French Inventory Adrien-Jean-Pierre Thilorier, Dry Ice has been used as a packing and preserving coolant. Because Dry Ice does not leave behind pools of liquid after it warms, it is much preferred over “wet ice” (frozen water) for the purpose of refrigerated commercial shipping.

When Dry Ice is added directly to a food product (like when making ice cream with CO2, freezing fruit, or carbonating a soda product), the carbon dioxide will react with water molecules in the food to create carbonic acid. This chemical gives the food a sour, acidic flavor, but can also add a very distinct fizz!

 

***Remember to ask an adult for assistance with these chilling Dry Ice experiments.***

And please use your new Freezing powers for Treats, and not for Tricks this Halloween!!!