Introduction: Freeze Water Instantly!
Okay, this experiment takes 6-10 days however the result is spectacular! I won't spoil it for you but the materials are easy and cheap to get if you don't have them. The correct scientific term for what you are doing with these materials is super-cooling or snap freezing which means that you keep water as a liquid, even below their freezing point.
Step 1: The Materials!
These materials as you recall are cheap and easy to get. The material that most people might not have is the thermometer and, or the distilled water. The materials that you will need are:
-thermometer (good range would be -10°C to 110°C)
-transparent plastic cups (tip: a tall, narrow shape works best)
-piece of cardboard (e.g., empty cereal box)
Step 2: Steps 1 , 2, and 3!
Cut a circle from the cereal box to use as a cover for the plastic cup.
Pour a small sample of distilled water into a clean plastic cup and place the cup in the center of the bowl.
Cover the cup with the cardboard, then add ice cubes to the bowl, so that the ice is above the level of water in the cup. Be careful not to get any ice inside the cup.
Step 3: Steps 4, 5, and 6!
Sprinkle two tablespoons of salt over the ice cubes. Be careful not to get any salt inside the cup.
Uncover the cup and put the thermometer inside.
Monitor the temperature of the water. Over the next 10–20 minutes or so, you should see the temperature slowly decrease. Keep track of the time and temperature in your lab notebook.
Step 4: Step 7, and 8!(The Last Steps Until It Looks Like That!)
When the temperature of the water reaches −1 to −3 deg;C or so, carefully remove the cup from the ice bath.
Repeat the procedure, testing different types of water to see whether it can be supercooled before freezing. For each type of water, run at least three trials (more is better). Here are some ideas for types of water to test:
bottled distilled water,
bottled spring water,
plain tap water,
any of the above that have been boiled and then allowed to cool to room temperature.
Step 5: How Did This Occur?
If you begin with a sample of distilled water, and cool it gradually, you can make super-cooled liquid water. When ice is added to super-cooled water, it acts to catalyze the crystallization of the liquid. The water instantly freezes solid. This is sometimes called "snap freezing". In this project you will use salt and ice to make a "bath" that is below the normal freezing point of water. The dissolved salt causes the bath to have a temperature below the normal freezing point of water. This pheonomenon is called freezing point depression. You can use your salt/ice bath to cool various water samples to investigate which samples can be super-cooled, and which samples freeze at the normal freezing point. It's fun to see water suddenly freeze solid.
Step 6: I Challenge YOU!
I would like to see you comment and post because I challenge you to see what kinds of liquids can you use to do the super-cooling and snap freezing!
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