Strong Ice

by
Barbara Pawela

This lesson was created as a part of the SMART website and is hosted by the Illinois Institute of Technology

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Most substances expand when they are heated.  Water has the unique property of expanding when it loses heat and turns into ice.  If you want to check this out , fill a small plastic container to the brim with water, and put a lid on as tightly as possible without spilling any water.  Put the container into the freezer.  Put each can of pop into a ziploc bag and  place into the freezer for two or three days.  The needed materials follow.

After the allotted time examine the effects of freezing on  the above- mentioned substances. After the water in the plastic container and the cans of pop have frozen , there is an alteration of shape or structural integrity of the cans,  and the lid on the plastic container is raised.   Keep the materials frozen  in a cooler with ice.  Display the cans and the plastic container, and examine them to see what happened.  Water in the plastic container and the water as a major component in the pop gives up heat.   A system may transfer energy to its surroundings by giving off heat or by doing work on the surroundings.  One way is if the system expands.  

Why  Does Water Expand  as It Freezes?

http://edie.cprost.sfu.ca/~rhlogan/water_ex.html

The reason water expands when its temperature cools below 4 degrees Celsius is due to hydrogen bonding.  Hydrogen bonding forms a weak bond between hydrogen atoms and  oxygen atoms of adjacent  water molecules as illustrated  below.  Once the temperature drops to 4 degrees Celsius, the molecules have less kinetic energy  and are closer together.  This allows hydrogen bonding to take place.   The hydrogen bonding pulls the molecules into an open crystalline structure that occuppies more space than liquid  water.     

 

 

 

Amery, Heather The Know How Book of Experiments, Tulsa: EDC PUBLISHING(1989)p.25

http://www.madsci.org/posts/archives/dec98/913733647.Ph.r.html

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