Dry Ice Halloween Science

Dry ice is a fascinating substance that can be used for science demonstrations. We highly recommend bringing it into class to show phase changes in matter.  Halloween is a perfect time to wow your students.

What is it?

Dry ice is the solid form of carbon dioxide.  Carbon dioxide is most commonly found as a gas.  It is the gas we exhale when breathing, and the gas plants take in for photosynthesis.  The chemical formula for carbon dioxide is CO_2.   Carbon dioxide gas is a heavier gas.  It will tend to float along the ground. 

How is dry ice different than frozen water?

The first difference is that dry ice is much colder than frozen water.  Water freezes at 0°C.  Carbon Dioxide freezes at –78.5°C.  This is why you must wear protective gloves.  It is so cold it will burn your skin.  

The second difference is how they melt.  Water will always melt from a solid to a liquid and then evaporate into water vapor.  Dry ice does not melt.  It goes through a process called sublimation.  Sublimation is when a solid directly changes into a gas.  It skips the liquid phase.  

As soon as you take out a piece of dry ice, it is sublimating into a gas.  This gas is very cold.  When the CO₂ gas touches the air, it causes the water vapor in the air to condense to form fog.  The fog you see is not CO₂ but liquid water.

Safety Precautions

Never, ever touch the dry ice.  It is so cold it will severely burn your skin.  You must wear oven mitts, thick gloves, or use tongs to handle dry ice.  

The room should be well-ventilated.  When the dry ice sublimates to CO_2, the gas can build up in the room.  You don’t want to breathe in too much CO₂.  

Never put dry ice in a sealed container because the container will explode.  Always wear safety goggles when working with dry ice.

What can we demonstrate with dry ice?

Dry is lots of fun and a great way to explore the properties of solids, liquids, and gasses.  Mainly gases.  Add water, and you get big bubbles and lots of condensation.  Change the temperature of water, and students get a great lesson on sublimation.  Put a little soap in, and you get foamy bubbles with fog inside.  Pop the bubbles, and the fog comes out.  How fun!!!!  Check out these videos to show you how to demonstrate this to your students.  

Try Dry Ice in Different Temperature Water.

Now add soap to the bubbling water.

Where do I buy dry ice?

I buy dry ice at a local grocery store.  You may need to search for a place that produces dry ice.  Searching online should help you find some.  Let your friends know you need dry ice.  Food shipments and medicine may ship with dry ice.  You might get lucky, and a friend just got a delivery.

How do I turn this into an experiment?

Are you looking to have students create investigations?  These investigation journals will help them through the process.  Perfect for classrooms and science fairs.  It is a wonderful way to have students take the lead in their learning.  

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