Friday, October 6, 2017

Day 2 13 Days of Halloween 2017



What is Dry Ice?

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

What does Dry Ice do?

Dry ice is special because it changes from a solid directly into a gas.  This is called sublimation.  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 in the air.

Safety Precautions

Never, ever touch dry ice.  It is so cold it will severely burn your skin.  Dry ice freezes at -78.5 degrees Celsius.  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.

The safety precautions may make you nervous, but dry is lots of fun and a great way to explore the properties of solids, liquids, and gasses.


Activities with Dry Ice
Fill a bowl with some water the warmer it is the more condensation you will get.  Add several pieces of dry ice to the water.  This will cause it to bubble.  As the carbon dioxide escapes the water, it will cool the air around it.  This will condense the water vapor creating a fog that will over flow the bowl.  This is the classic dry ice activity.

Dry Ice Smoke Bubbles
For a surprise add a couple drops of soap to your bowl of water and dry ice.  You will immediately see bubbles come up.  You can touch them.  When they pop they let out what looks like little puffs of smoke.  It is actually water vapor.  This one always gets students excited.


Color Changing Dry Ice
Did you know dry ice is an acid?  First make red cabbage juice.  Red cabbage juice is an acid/base indicator.  Just take a red cabbage and boil it in water until the water becomes a nice purple color.  When an acid is added to the cabbage juice it will change to pink or red.  When a base is added it will change to green.  Here is a video my son did for a class project.  I think he does a pretty good job explaining.  It will definitely excite your students.  



Don't forget to come back tomorrow for Day 3.  


Looking for more ideas.  I can't wait to try some of these.  They get very creative with dry ice.



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