Supercooling water experiment
Filtered water is not only good for drinking and keeping hydrated, you can also use it to explore science and entertain the kids with the supercooling water experiment. Below we will explain how to demonstrate the phenomena of supercooled H2O.
Supercooling is the process of lowering the water’s temperature below freezing point, without it becoming a solid and then watching it rapidly freeze when force is applied.
What do I need?
To start, you’ll need 2 plastic bottles of clean, filtered water and place them in your freezer for 2-3 hours. Try to put them in the coldest part of the freezer, which is usually the ice tray section.
How does it work?
Water is usually in a liquid state at room temperature, this is as a result of the molecules vibrating, flowing and tumbling past each other (this is what makes water flow). When a liquid becomes solid, these molecules come together and lock into place. They still vibrate, but instead of moving past each other, they stick together.
In the instant ice experiment, you’re supercooling the water to below zero degrees. However, it’s difficult for pure or filtered water to become a solid without somewhere for the ice crystals to start growing. The impurities in untreated water naturally act as spots where the crystal can start forming. Some kind of nucleation event is needed for pure water to turn solid.
Nucleation is the first step in the development of a new thermodynamic phase and determines how long you have to wait for this new phase to appear. For example, when you bang the water bottle against a hard surface, it will cause a few molecules to line up and start forming the ice crystal from the top down.
I’ve supercooled the water, what do I do next?
Step 1 – Carefully remove one of the bottles from the freezer. Don’t bump, drop or shake it. Leave the other bottle in the freezer in case the first one isn’t cold enough.
Step 2 – Bang it on the kitchen table and watch the ice crystal growing from the top to the bottom of the bottle.