Science Fun with Dry Ice

In this simple investigation, you'll learn some of the science behind a very cool substance known simply as dry ice. In the process, you'll learn a little chemistry and some great science lingo.  Can you say...sublimation?

Here's What You Need:

• Large plastic bowl, plastic cup, or graduated cylinder
• Warm water
• Dry Ice (you can usually find it at the grocery store or some ice cream shops ~$1/lb)
• Liquid soap
• Heavy duty gloves or tongs (for handling the dry ice)
• Hammer or mallet (for breaking the dry ice)
• Ice chest or cooler (for storing dry ice)

Safety & Dry Ice: Dry ice must be handled carefully and with adult supervision.  Because it is extremely cold (-109.3°F or -78.5°C), it can easily cause server damage to your skin if it is handled in incorrectly.  Avoid touching dry ice with unprotected skin. Never swallow dry ice or place it in your mouth.

Here's What You Do

Fill the bowl, cup, or graduated cylinder with warm water (a bit more than half way).  Use the mallet or hammer to break the dry ice into pieces that will fit easily into the container.  Using the tongs or gloves, carefully place a few pieces of dry ice into the warm water. Immediately, the water should start to churn and bubble!  You may also notice a smoky cloud forming on the top of the container and eventually spilling over the side. This cloud is safe to touch and feel.  Just remember to avoid touching the dry ice directly. After a while, the bubbling and smoking will slow down a bit.  Simply, poor out a bit of the water (cooled by the dry ice) and replace it with some warm water. 

Now, let's ramp things up a bit.  While the water is churning and bubbling, add a few drops of liquid soap and watch what happens! After a few seconds, you should see some fog filled bubbles rising out of the water.  Once again, these are perfectly safe to play with.  Grab a handful of the bubbles and squeeze them in your hand.  Notice anything? They are full of the smoky clouds that you observed when you dropped the dry ice in the warm water. 

The Science Behind Dry Ice

Dry is actually the solid form of carbon dioxide. Usually, when we talk about carbon dioxide, we talk about it as a gas; the one that we exhale during respiration and plant use for photosynthesis.  About 0.035% of the air around us is made up of carbon dioxide (most of our air is made up of nitrogen - 79%). Dry ice acts very differently than water based ice.  For example, under normal atmospheric conditions dry ice does not melt (that's why we call it dry ice).  Instead solid dry ice turns directly into carbon dioxide gas through a process called sublimation.

Try this. Grab two plates. Place a piece of dry ice on one plate and a piece of water based ice on the other plate.  Now, wait.  After an hour, you'll notice that the dry ice seems to have disappeared and there is a puddle of water where the water based ice was.  However, the dry ice didn't disappear.  Instead, it changed into a gas (one that is invisible to the naked eye).  

We make dry ice by placing gaseous carbon dioxide under intense pressure (about 870 pounds per square inch) at a very low temperature.  This will turn carbon dioxide gas into liquid carbon dioxide. The liquid carbon dioxide is then pushed through an expansion valve and into a pressure chamber.  The change in pressure causes the temperature to drop and the liquid carbon dioxide changes quickly to a solid...dry ice!   

Wondershop Fast Fact

Dry ice is great for keeping things cool.  In fact, one pound of dry ice cools three times better than a pound of water based ice.  Often people will use a mixture of dry ice and water based ice to keep things cool while they are shipped.

Most Groundhogs Predict an Early Spring!

It’s February 2nd!  You know what that means…Groundhog Day! If you are not familiar with this particular observance, this is how the whole thing works. Early in the morning on Februay 2nd, people gather around the burrow of a Marmota monax; a large rodent also known as the whistle pig, eastern marmot, southern marmot, monk, woodchuck, or groundhog. It is believed that if the groundhog sees its shadow when it climbs out of the burrow, there will be six more weeks of cold, wintery weather. On the other hand, if it doesn’t see its shadow, the warmth of spring will arrive soon. Here’s an additional little nugget to impress your friends with today: Groundhog Day is a cross-quarter day. That means it fall halfway between the Winter Solstice and Vernal Equinox.


There are a number of cities that host their own Groundhog Day celebrations…complete with their own groundhogs. Here are some of the results from this year:

• Punxsutawney Phil (Punxsutawney, Pennsylvania): Six more weeks of winter
• Jimmy the Groundhog (Sun Prairie, Wisconsin): Early Spring 
• Wiarton Willie (Wiarton, Ontario): Early Spring 
• French Creek Freddie (French Creek, West Virginia): Early Spring
  
• General Beauregard Lee (Lilburn, Georgia): Early Spring 
• Chuckles (Manchester, Connecticut): Early Spring 
• Dunkirk Dave (Dunkirk, New York): Early Spring 
• Gus (Athens, GA): Early Spring
• Buckeye Chuck (Marion, Ohio): Early Spring 
• Octoraro Orphie (Lancaster, Pennsylvania): Early Spring
• Grady the Groundhog (Chimney Rock, North Carolina): Six more weeks of winter
  
• Staten Island Chuck (Staten Island, New York): Early Spring 
• Dover Doug (Dover, Pennsylvania): Early Spring

Is there any science behind this whole Groundhog Day thing?
I did a bit of research and this is what I found out. Historically, people have observed animal behavior for clues to changes in the weather. For example, geese flying south is a sign of the coming of fall for many people living in the United States. The reappearance of hibernating or inactive animals is a sign of winter’s end. When German settlers came to Pennsylvania in the 1700s, they selected the groundhog as their seasonal forecaster.

There may also be a meteorological explanation for groundhog day. It is thought that the observance may have roots in a weather phenomenon described in the Scottish poem below:

If Candlemas Day is bright and clear,
There’ll be two winters in the year.

The idea behind this poem can be found in cultures around the world. In the poem, Candlemas Day refers to February 2nd…Groundhog Day. Farmers in ancient Europe noticed that bright, clear winter days are often very cold. We now know that this is caused by high pressure systems. Areas of high pressure pull cold air down from the north. They also sweep away any clouds that might have provided insulation. Consequently, a bright winter day (one on which a groundhog may see a shadow) may be an indication of more cold days to come.

Of course, none of this is sound evidence that groundhog can actually predict the coming of spring. Instead, Groundhog Day can be seen as a celebration of the role of scientific observation and prediction in our world. Every day, we make observations about the world around us, attempt to make meaning of those observations, and create predictions about the way things will happen in the future. Groundhog Day is wonderful example of this. Over the course of time, we have combined our observations of animal behavior and weather to create a system for predicting spring. Does it work? Well, that is a question I will leave to you and your children to explore.

Other great sites to check out on Groundhog Day:

• Groundhog Central
• Kaboose on Groundhogs Day