To read the interesting history of this article, please see here.

A majority of you reading this article can remember learning about the molecules that make up gas, liquids and solids. Maybe it was last year or maybe in a fun little children’s book, or maybe you are learning about this for the first time.

Basically, when you have water you have these atoms identified as H2O. That means you have one oxygen atom connected to two hydrogen atoms. This is a basic structure. Well, water, as a liquid, has weak hydrogen bonds between itself and the other atoms (one drop of water can contain 6X1023atoms). That means that the hydrogen atoms connected to the oxygen atoms are being attracted to each other. This creates the structure for a water molecule.

Photo from Wikipedia

However, as the temperature of the water drops these atoms are attracted to each other with more intensity. So, as these atoms begin to come together they form a certain structure. It also creates a wide (if you can call such a miniscule width “wide”)  area between the water molecules. Because of this the water becomes a solid, ice.

It is at this point that the ice begins to expand.

When the water molecules bond together (called a hydrogen bond) they form a structure that has a area between them that cannot be used as free space. So, when quadrillion and quadrillions of atoms are connecting you have a water structure that takes up more space then the jumbled together water molecules.
To show, as best we can, how this works we are going to do an experiment that is both fun and contains scientific value.

What We Need:

  • Water Bottle (plastic ones, do not use a real water bottle)
  • Water
  • Freezer

Directions:

  • First, fill the water bottle to the very top and put the top on tightly.
  • Next, place the bottle in the freezer for 9-12 or more hours.
  • When you are done freezing remove the water bottle from the freezer and let thaw without opening it.
  • Note: you may want to do these next parts outside.
  • Here is the fun part. Do not let the ice thaw for over two hours because, sometime after this point, the water molecules restore to their normal positions and give worse results.
  • Now, when you have let the bottle thaw for 1-2 hours give it to a friend or sibling that has a good sense of humor. Acting very scientific like, ask the person to open the bottle quickly. A couple tablespoons or more will spray/pour out of the bottle.
  • If the person keeps a steady hand you will be able to see that the water will still be at the very top of the water bottle.

Although your friend or sibling may get a little wet, you will have learned a lesson that when ice freezes it actually expands as water molecules combine and take up more space and thus gives greater pressure and less space for the water molecules to occupy. It also makes for an interesting prank. Quite amazing!

Note: One might wonder why the water bottle stills sprays if it has thawed and, thus shrunk, but, when the ice first expanded it expanded the bottle. And, when the ice has thawed for a couple hours then the water around it shrinks but is still pressured because of the remaining ice. Thus, when opened, the bottle will release the pressure, and some water. All quite interesting and rather fun.

 

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