Supercooling a liquid is a really neat way of keeping the liquid a liquid below the freezing temperature. Normally, when you decrease the temperature of water below 32oF, it turns into ice. But if you do it gently and slowly enough, it will stay a liquid, albeit a really cold one!
In nature, you’ll find supercooled water drops in freezing rain and also inside cumulus clouds. Pilots that fly through these clouds need to pay careful attention, as ice can instantly form on the instrument ports causing the instruments to fail. More dangerous is when it forms on the wings, changing the shape of the wing and causing the wing to stop producing lift. Most planes have de-icing capabilities, but the pilot still needs to turn it on.
We’re going to supercool water, and then disturb it to watch the crystals grow right before our eyes! While we’re only going to supercool it a couple of degrees, scientists can actually supercool water to below -43oF!
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Yes, sorry about that. We were not able to include the image so I’ve deleted the sentence. Thanks.
The last line here states: “Here’s an image of how the shape of the ice crystals are affected by magnetism:” I do not see an image here. Is it my side or the website? Thank you.
This changes the solution in the glass, which changes the freezing temperature.
Remind me again why we can’t get salt in the glass and what ‘ll happen if we do?
As I have always known, it is very hard to crystallize a liquid without a nucleation site. In chem lab we often scratch the inside of a beaker with a glass rod to make micro scratches for crystals to form on. The “pure” water the you got from a store was not particulate-free in the true scientific sense. There were also possible scratches or nucleation sites on the interior of the container as well as “invisible” particulates. You can super cool or super saturate a solution without solidification until a bump or a scratch or a speck of dust contacts the fluid and..bang.. crystallization.
At the other end of the liquid heating/cooling phenomenon, the same thing occurs if you heat a mug of water in a microwave in a brand new glass mug that has no scratches. There are no sites for the bubbles to form on so the water super heats above its boiling point until a vibration or just too much heat is applied and it flashes and “bumps” out. That’s why putting a bamboo skewer in the cup of water prevents flashing due to gas bubbles trapped and released in the wood during heating.
So can it happen without particulates? Probably. But it takes a lot of energy for colliding molecules with the correct orientation to begin the process. A catalyst like Pt is often used in hydrogenation reactions. The Pt atoms are just the right distance from one another for the H2 molecule to become adsorbed to the surface. A carbon-carbon covalent double bond then has a better chance to react during collision than with a free H2 molecule. Once again, such a surface interaction is common place in chemical and physical processes. Hope this helps and not too technical!
Aurora
We have followed you and SuperCharged Science for quite some time and we have really learned a lot from you. We trust your knowledge and today have a question for you. We understood it to be the case that you can’t freeze purified water due to the lack of particulate debris for the crystals to grow on. We happened to have a bottle of purified water the other day and my daughter wanted to test that understanding. Long story short, it did freeze solidly over night. So, is the understanding we had incorrect OR is the purified water from the store not ACTUALLY purified OR is there some other explanation that we are perhaps overlooking(underwent purified process,but not a true purification and is able to be sold as ‘purified’)? We would appreciate your input either by your explanation or direction to helpful science link(s) that would allow us to find the answer ourselves. I don’t remember if you have a study on water properties and freezing etc. I am sure you likely do, but wanted to ask you directly. I hope our question has been asked clearly.
At least a couple of tablespoons.
How much salt do you put on top of the ice??
A little is ok – you want the salt on it ice itself.
I am not sure what happened when you say it didn’t work… what exactly happened?
BTW: This one is harder to do than the hot icicles, so you might want to try that one first!
i tried it and it didn’t work 🙁
…what should i do?
what if i get salt in the water?
THe salt on the ice has the effect of making the ice bath “cooler” than with just ice.
Does the fact that there was salt on the ice cube when you dropped it in affect how the water crystallizes?
I’ve done this with bottles of water. You place them in the freezer and wait 15-20 minutes and if you tap the cap and they’re cold enough it’ll freeze into a block of ice right before your eyes.
Great question! The main reason that ponds don’t freeze is that it takes a long time to do so. In general, if the temperature is low enough and you wait long enough, it will freeze solid. Remember that the earth below the pond is a heat source, and water’s lowest density occurs at 4 degrees C, so as water cools down it falls to the bottom of the lake, but as water cools below 4 degrees C it will rise back up to the surface, which is why lakes freeze from the top down. The layer of ice on the top acts as an insulator to it makes more time/effort to freeze further down.
Hi Aurora
Love your Science. We have a question that we are not able to answer. Why didn’t our pond freeze over completely during the single digit temperatures when it had frozen over earlier in the week when temps were only in 20s.
H2O cubed (just kidding)
It’s still the same “H2O”, since the molecule for water is the same for the substance no matter what state it’s in.
(I’d tell you more chemistry jokes, but all the good ones Argon.) 🙂
If H2O is the formula for water, what is the formula for ice?
It sounds like your water wasn’t cold enough. Put it overnight in the fridge or pile the ice higher than the level of water in the bowl. You can put the bowl with the ice and water int he fridge to chill it faster. Let me know how it goes!
i was expecting for there to be ice crystals in the water. when i put the salted ice cube into it nothing happened.
what do u think i should do. 🙁
Can you explain more about what didn’t work? What did you expect or not expect, and what actually happened? Since I am not right there with you, it’s a little hard to troubleshoot with a little more info. 🙂
the experiment didn’t work what should i do?
You have to go very, very slowly. The water pouring out is like a thin thread. You can easily do this with sodium acetate, which is in the Hot Icicle experiment.
Hi – so we were really intrigued by the graphic for this experiment. Though we enjoyed the experiment itself, how would we get it to look like the picture of water pouring and building an ice column? Thanks!
When you add salt, the temperature that the ice freezes at decreases. The more ice you add to water, the lower the freezing temperature. On the road, people sprinkle salt on the ice so they can melt it quickly and easily. The salt dissolves into the liquid water in the ice and lowers the freezing point. We use it to make the ice slightly colder than usual so it can bring down the temperature of the water a little more. Try leaving the whole thing in the fridge overnight and see if that helps!
I tried a few times, but it still didn’t work. 🙁 Why do you put salt in the ice?
Because we’re cooling it down very carefully and slowly, so the molecules don’t link up in the solid form yet.
Why does it stay a liquid instead of freezing?
Did it work when you tried it again? If it still didn’t work and you didn’t get any salt into the solution, it means your water wasn’t cold enough. Try leaving a glass of water in the fridge overnight, then trying this first thing in the morning. 🙂
no it didn”t
Oops – it probably didn’t work then, right? That’s because you changed the solution in the glass, which now has a different freezing temperature. Wash it out and try again!
i got salt in the H20