Wednesday, October 19, 2016

13 Days of Halloween: Dry Ice

Today I am teaching a lesson with dry ice.  A perfect day to blog and create some videos while I set up.  I hope you are enjoying the 13 Days of Halloween.

What is it?

Dry ice is the solid from 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 CO2.   Carbon dioxide gas is a heavier gas.  It will tend to float along the ground. 

What is different about dry ice 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 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 CO2 the gas can build up in the room.  You don’t want to breath 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.

Dry is lots of fun and a great way to explore the properties of solids, liquids, and gasses.

Try Dry Ice in Different Temperature Water.
Now Add Soap to the Bubbling Water.

I buy dry ice at a local grocery store.  You may need to search for a place that produces dry ice.  Searching on-line should help you find some.

  Are you looking to have students create investigations.  These investigations journals will help them through the process.  Perfect for classrooms and science fairs.

Keep coming back for the 13 Days of Halloween.  Don't forget to enter the Rafflecopter.

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