You won’t believe your eyes when you watch a glass of water instantly freeze when an ice cube is placed in the water! Let’s get started with this super cool science experiment and learn How to Freeze Water Fast.
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This is such a fun and fascinating experiment and a great way to teach kids about the freezing point of water!
How to Freeze Water Fast
How to Freeze Water Without a Freezer
- Fill a large bowl with ice, 2 or 3 sealed water bottles, and some rock salt.
- Stick a thermometer into the bowl of ice and wait for the temperature of the ice water in the bowl to drop to 17º-20º F.
- Gently pull one of the bottles out of the bowl and pour it into a clear glass cup or jar.
- Grab an ice cube and place it in the glass of very cold water to watch the water instantly freeze into ice!
- Repeat steps 3-4 with your remaining supercooled water bottles to watch the ice form before your eyes again and again!
Step 1: Add Ice, Rock Salt, and Water Bottles Into a Large Bowl
Although this super cool experiment does freeze water in an instant, there is a little bit of prep time that we need to do first to get the temperature of the water bottles to just the right point where they will freeze!
So go ahead and fill a very large bowl with lots and lots of ice cubes! Then stick 2 or 3 sealed water bottles into the icy bowl.
Now scatter some rock salt on top of the ice in the bowl. Be very generous with the rock salt. The properties of salt actually allows ice to melt at a temperature below the freezing mark (32°F or 0°C).
As the ice melts into an icy-watery mixture in the bowl, it will remain below freezing thanks to the salt. This will cause the water inside the water bottles to drop below freezing without turning to ice!
Step 2: Use a Thermometer to Monitor the Temperature of the Ice
Grab a cooking, or meat thermometer and place it in the ice near the bottles. It should take at least 30 minutes for the temperature to get where it needs to be, but could take up to 90 minutes.
This step is probably the hardest part if you lack patience like I do…but it’s crucial in order to get the water in the bottles to be supercooled to the right temperature.
Supercooling the water is the scientific term for when a temperature of a liquid drops below it’s freezing point and remains a liquid (water) without turning to a solid (ice).
We need the temperature of the ice water in the bowl to be between 17°-20°F for the water inside the bottles to get supercooled.
If you don’t have a thermometer on hand, another great sign that your water bottles are cold enough to make liquid ice is to check the outside of the bottle for frozen condensation droplets.
If the condensation on the outside of your bottles have become frosty or frozen, the liquid inside the bottle is likely cold enough to move on to the next step to make water freeze fast!
Step 3: Pull a Bottle Out and Pour it Into a Clear Glass
Once you determine that your water bottles have cooled to that magical 17°-20°F temperature range, gently pull one of them out of the bowl.
Just a slight shake of the bottle could be enough to prematurely kickstart the freezing process and you will end up with a frozen bottle of water (which is still fascinating, but not the end result we want this time).
While being careful not to disturb the water more than you have to, pour one bottle of water into a clear glass cup or jar.
It’s best to fill the glass very close to the top with the supercooled water out of the bottle.
Depending on the size of your glass you may need to use 2 bottles, but I prefer to save the 2nd and 3rd bottles to repeat the process you are about to witness!
Step 4: Touch an Ice Cube to the Water in the Cup
With your glass nearly filled to the brim with liquid water that is below the freezing point, grab an ice cube and place it in the top of the water.
Depending on the temperature of your water, it might take a few seconds for the reaction between the ice cube and the supercooled water to be seen.
After a few seconds the water in the jar will begin to crystalize and solidify into a slushy, icy drink! It is mesmerizing to watch this ice making process unfold right before your eyes!
Step 5: Repeat the Process With Multiple Bottles to See the Ice Form Again
Now that you have learned how to freeze water fast why not have some fun making more ice with your other bottles that are supercooled!?
You can repeat this same super cool experiment again by repeating steps 3-4, or you could try some other cool things with your supercooled water like making ice pillars in this How to Turn Water Into Ice Instantly experiment!
Can Ice Cubes Freeze Water?
It is more typical that ice cubes melt into a glass of cold water than it is for ice cubes to freeze a glass of water. This is because water needs to lose a lot of heat energy to drop below freezing.
Most household ice is at a temperature of about 23°F, so it doesn’t take much heat energy from water to melt the ice cubes, however there are a few cases in which ice cubes can freeze water!
In our experiment how to make water freeze fast, the water bottles were already supercooled and remained as a liquid below freezing.
The below freezing water just needed an ice cube or particle to crystalize onto to start the ice forming process.
Adding the ice cube to the supercooled water did turn the water into ice because the water was already below freezing.
Another way to turn water into ice with an ice cube would be to use ice cubes that are very cold to allow them to absorb enough heat energy from the water without the ice cubes melting.
This typically doesn’t happen unless the environment (outside, freezer, etc.) is below freezing and freezes the water and keeps the ice frozen too!
How Does Water Freeze Into Ice?
Liquid water typically freezes into a solid form of ice when the temperature of the water drops at or below 32°F. This is the temperature that water molecules slow down enough to stick to each other and form a solid crystal.
From this experiment, we learned that water does not always follow the rule of freezing at 32°F though. Under the right conditions, purified water that does not have impurities and minerals can drop below the freezing point and remain a liquid and is referred to as supercooled water.
What causes freezing rain?
Freezing rain is a great example of supercooled water in the atmosphere. This fascinating weather phenomenon occurs when warm air (above freezing) rises up and over cold, (below freezing) air at the surface.
As the precipitation falls out of the clouds into the warmer air, it melts and becomes all rain until it reaches the thin layer of cold air near the ground. This cold layer of below freezing air near the ground supercools the rain drops.
Even though the raindrops have been supercooled to a temperature below freezing, they do not have time to freeze during their short trip through the shallow layer of cold air.
These below freezing supercooled raindrops then freeze immediately on contact with anything they contact at the surface including cars, roads, trees, sidewalks, etc. Freezing rain storms are often called ice storms and can make very dangerous winter conditions.
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