Did you know that supercooled liquids need to heat up in order to freeze into a solid? It’s totally backwards, I know…but it’s true! Here’s the deal:
A supercooled liquid is a liquid that you slowly and carefully bring down the temperature below the normal freezing point and still have it be a liquid. We did this in our Instant Ice experiment.
Since the temperature is now below the freezing point, if you disturb the solution, it will need to heat up in order to go back up to the freezing point in order to turn into a solid.
When this happens, the solution gives off heat as it freezes. So instead of cold ice, you have hot ice. Weird, isn’t it?
Sodium acetate is a colorless salt used making rubber, dying clothing, and neutralizing sulfuric acid (the acid found in car batteries) spills. It’s also commonly available in heating packs, since the liquid-solid process is completely reversible – you can melt the solid back into a liquid and do this experiment over and over again!
The crystals melt at 136oF (58oC), so you can pop this in a saucepan of boiling water (wrap it in a towel first so you don’t melt the bag) for about 10 minutes to liquify the crystals.
Please login or register to read the rest of this content.
Yes you can touch it, but if you have sensitive skin use gloves because sodium acetate can irritate your skin if you’re sensitive. And you have to heat it up again to melt it, just like you did before!
Can I touch the hot icicle after I sculpture it? And does it melt on its own like normal ice??
Yes, even the slightest disturbance can trigger the phase change to start. You can place it in a clean glass jar in a pot of warm water on the stove, then slowly bring the water up in temperature. As soon as the crystals have liquefied, remove it from heat without disturbing it and let it cool. Then you can start again. You can dispose of it in the trash. It’s totally reusable over and over, so if you think you might want to do it again, just store it for later use.
And yes, many students are so perfection-driven that it either paralyzes them so they do anything at all, or are so terrified of making a mistake (and a mess) that no science ever gets done at all. Science is all about making mistakes, learning, and asking questions. If it’s not messy, wet, or on fire, you’re not doing it right. *smile* Seriously, if you can relax, enjoy and have fun during the process, you’ll be more resourceful and inquisitive during the process, and that’s what science is all about.
They have kid size plastic gloves on places like Amazon.com, or I’ve used a loose rubber band around the wrist to secure plastic grocery bags for small hands in a pinch.
We tried the experiment as instructed and when the second packet was snipped it immediately started to crystalize, we will try again as suggested above. Is ok to store the sodium acetate in a glass jar (clean jelly jar with lid) with a tight lid if not what do you suggest? Lastly, what is the best way to dispose of the sodium acetate and the plastic bags it came with?
Loved the experiment. Thank you for the statement, “Being resilient is one of the marks of a great scientist…” was priceless, as my son likes everything to work exactly as planned the first time.
The disposable plastic gloves I have are too large for my fifth grader, do you have a suggestion as to where to purchase plastic gloves for children, bulk or non-bulk.
PS: We ordered our packets from Walmart.
It’s super-easy to trigger this phase change! Just bumping it will often start it. Put it in a pot of hot water and it will liquify and you can try again.
Hello Aurora. My chemistry class and I have done this experiment twice now and both times the first pack worked but the second pack, as soon as we open it, it crystalizes instantly instead of staying a liquid to pour over the first crystal. We did not snap the metal disc inside the second one.
The excess liquid is water, which will evaporate when you boil it. Do not use your good pots/pans for this – get an old one from a thrift store you can use just for chemistry. 🙂
Thanks for the feedback. How do I remove the excess liquid? How do I know which is liquid and which not when I boil it? Sorry for the stupid question.
Hi Maryna,
It’s hard to say without seeing your experiment first hand, but my initial guess is that the solution isn’t super-saturated (too much liquid for the amount of solids). Did you find the hand warmer packets, or did you make your own? You can save it and boil it in an old pot to remove the excess liquid and then try again. It’s reusable, over and over. Keep trying – you can do it!
Being resilient is one of the marks of a great scientist… they get curious about why their experiment gave a result other than the one their were expecting, and then they get really excited because they get to learn something they can’t known or counted on before! 🙂
Our experiment did not work. Gosh we were so excited after having a very hard time finding the packets. (here in SA when I asked around people thought I was crazy)
We did exactly what the video said, placed crystals on the surface and poured very slowly the liquid from the other sachet. It just ran over the crystals and nothing happened, after a little bit it just formed a salty layer where the liquid ran off. It did not build up or anything. What is going on? 🙁
That’s ok – just warm it back up in a pan of boiling water (if you snipped the bag open, stick it inside a second bag and wrap it in a towel first). You can find all the chemical safety information for sodium acetate here. It’s basically an mild irritant to the skin.
Hello! Unfortunately, we were not able to make the sculpture. I must have triggered the reaction inside the unused packet when I snipped the corner.
Also, why is the sodium acetate dangerous to touch?
Thanks!
What web browser and type of device (or is it a computer) that are you using?
Why can’t I click on the link for the worksheets and exercises!?!?
the EZ packet is sodium acetate, so simply use what you have. If it’s in liquid form, then you’re set to go. if it’s in solid form, you may have to dissolve it in a little water first if it’s had all the water removed (it will look like little white pellets usually). If you’re not sure, place it in a double boiler and slowly heat it up and see if it goes easily to liquid form (should take about 10 min for a big chunk). Don’t use your kitchen pots for this experiment!
We don’t have access to an EZ heat packet but do have sodium acetate. How can we do the experiment without the packet? Thanks for your help.
Yes you can do this, but it takes a LOT of baking soda and vinegar to do this, and you will ruin one of your pans because you have to boil off the liquid to get the solid particles.
Thanks for responding. I will check my local sporting store for the warmers. I saw some videos (about.com & youTube) on how to make your own Sodium Acetate with Vinegar and Baking Soda. What are your thoughts on this? Safe? Does it make a good substitution for buying it?
Thank you!
I got mine in the video from my local sporting goods store for about $1-2 each. I know Amazon can be expensive sometimes! That’s the cheapest place I’ve found them.
Where do you recommend we buy the sodium Acetate? I see it at Amazon for about $8.00 for 2 small packs of EZ Heat.
That seems expensive.
Thank you!
AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!