the hot ice experiment

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Make Hot Ice From Baking Soda and Vinegar

Hot ice is another name for sodium acetate (CH 3 COONa or NaOAc). It is the sodium salt of acetic acid, which is the key component of vinegar. Hot ice gets its name from the way it solidifies. A solution of sodium acetate supercooled below its melting point suddenly crystallizes. Heat is released and the crystal resemble ice so… “hot ice.” All you need to make sodium acetate and crystallize it into hot ice is baking soda and vinegar. It’s a great chemistry demonstration because it illustrates chemical reactions, supercooling, crystallization, and exothermic processes . From start to finish, the project takes less than an hour. Once you have the sodium acetate, you can melt and crystallize it over and over again.

You only need two ingredients, plus a pan and stove:

• 1 liter Vinegar (weak acetic acid)
• 4 tablespoons Baking soda (sodium bicarbonate)

The quantities of baking soda and vinegar are not critical so long as all of the baking soda dissolves. If measuring the ingredients isn’t an option, just dissolve baking soda in vinegar until no more dissolves, filter off the liquid using a coffee filter or paper towel to remove any solids, and proceed from there.

Be sure to use plain white (clear) vinegar and not cider, red wine, or some other colored vinegar. You can substitute sodium carbonate (washing soda) or sodium hydroxide (caustic soda or lye) for the baking soda. If you have access to pure sodium acetate (inexpensive online), you can skip the procedure to make it and go directly to the step for re-using it.

• The first step is reacting the baking soda and vinegar . Stir baking soda into vinegar a little at a time. If you add it all at once, you’ll basically get the classic baking soda and vinegar volcano and could overflow your pan! The reaction between baking soda and vinegar produces sodium acetate, water, and carbon dioxide gas: Na + [HCO 3 ] –  + CH 3 –COOH → CH 3 –COO –  Na +  + H 2 O + CO 2 However, at this point there’s too much water for the sodium acetate to crystallize.
• Next, concentrate the solution by boiling it. It took me about an hour at medium heat to reduce the volume from a liter to about 100-150 milliliters. Don’t use high heat because you may get discoloration (golden or brown). The discoloration doesn’t ruin the sodium acetate, but the hot ice will look a bit like you made it from yellow snow. You’ll know you’ve boiled off enough water when a crystalline skin starts to form on the surface of the liquid.
• Once you see a skin, immediately remove the pan from the heat. Carefully pour the liquid into a clean container and cover the new container with plastic wrap or a lid to prevent further evaporation. You should get crystals in the pan, which you can use as seed crystals for activities, but the liquid in the new container should not contain any crystals. If you do have crystals, stir in a very small volume of water or vinegar to dissolve the crystals. If the entire solution crystallizes, add more water and go back to the stove to boil it down again.
• Place the covered container of sodium acetate solution in the refrigerator to chill it. It’s also fine to let the solution cool to room temperature on its own, but this takes longer. Either way, reducing the temperature produces a supercooled liquid. That is, the sodium acetate remains liquid below its freezing point.

Hot Ice Activities

Solidification of sodium acetate is the basis for one type of hot pack , but it’s also great for crystallization demonstrations. Three popular activities are the “sea urchin,” “flower,” and “tower.”

• Sea Urchin : Pour the cooled liquid into a clear container. Use a toothpick or bamboo skewer to scrape a few sodium acetate crystals from the pan used to make the solution. Dip the toothpick into the liquid so the tip with crystals are in the middle of the container. Needle-like crystals immediately grow out from the center. Also, crystallization releases heat as chemical bonds form to make the solid. The final structure resembles a spiny sea urchin.
• Flower : Pour the cooled sodium acetate liquid into a flat dish (preferably a dark-colored one). Scrape one or more crystals from the pan and drop them onto the liquid. The crystals act as seeds . The hot ice crystals spread out radially and form structures that resemble flowers.
• Tower : Place a few crystals onto a surface. Slowly pour the liquid onto the crystals. The hot ice solidifies as you pour the liquid, forming a tower (or whatever shape you can manage).

Re-Using Hot Ice

Save the solid sodium acetate so you can use it again without going through the whole baking soda-and-vinegar process. Simply dissolve the hot ice in water and boil off the smaller amount of excess water.

Safety Information

Sodium acetate is a safe, non-toxic chemical, so it’s perfect for chemistry demonstrations. It is used as a food additive to enhance flavor and is a key ingredient in some chemical hot packs. The heat released by hot ice crystallization of a refrigerated solution doesn’t present a burn hazard. However, making hot ice from baking soda and vinegar does involve boiling liquid on a stove, so adult supervision is required. If you use sodium hydroxide in place of baking soda, heed the cautions on the product label.

• ChemEd Xchange (2019). “ Crystallization of Supersaturated Sodium Acetate – Demonstration .”
• Clayden, Jonathan; Greeves, Nick; Warren, Stuart; Wothers, Peter (2001). Organic Chemistry (1st ed.). Oxford University Press. ISBN 978-0-19-850346-0.
• Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds . Van Nostrand.

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Hot Ice Crystal Towers

  Secondary | Materials | Views: 73280

Did you Know?

• Sodium acetate or hot ice is an amazing chemical you can prepare yourself from baking soda and vinegar. You can cool a solution of sodium acetate below its melting point and then cause the liquid to crystallize.
• The crystallization is an exothermic process, so the resulting ice is hot.
• Solidification occurs so quickly you can form sculptures as you pour the hot ice.

Health and Safety: This experiment involves boiling solutions. Please take care when doing so and ensure you have adult supervision.

You will Need:

• 4 tablespoons of baking soda
• 1 litre clear vinegar

The concepts it illustrates are:

• Supercooling
• Crystallisation
• Exothermic Chemical Reactions

What to Do:

• In a saucepan, add baking soda to the vinegar, a little at a time and stirring between additions. The baking soda and vinegar react to form sodium acetate and carbon dioxide gas. If you don’t add the baking soda slowly, you’ll essentially get a baking soda and vinegar volcano, which would overflow your container.
• You’ve made the sodium acetate, but it is too dilute to be very useful, so you need to remove most of the water. Here is the reaction between the baking soda and vinegar to produce the sodium acetate: Na + [HCO 3 ] – + CH 3 –COOH → CH 3 –COO – Na + + H 2 O + CO 2
• Boil the solution to concentrate the sodium acetate. You could just remove the solution from heat once you have 100-150 ml of solution remaining, but the easiest way to get good results is to simply boil the solution until a crystal skin or film starts to form on the surface. This should take about an hour on the stove over medium heat. If you use lower heat you are less likely to get yellow or brown liquid, but it will take longer. Some discolouration is normal.
• Once you remove the sodium acetate solution from heat, immediately cover it to prevent any further evaporation. Pour the solution into a separate container and cover with plastic wrap. You should not have any crystals in your solution. If you do have crystals, stir a very small amount of water or vinegar into the solution, just sufficient to dissolve the crystals.
• Place the covered container of sodium acetate solution in the refrigerator to chill and await the amazing results!

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How to Make Hot Ice From Vinegar and Baking Soda

Categories STEM Activities

Kids will love this wacky edition of winter science experiments ! Hot ice is a novelty any time of year. Learn the no-fail way for how to make hot ice here!

We watch a lot of science-themed YouTube videos, so of course, when we saw this video, we knew we had to try and make our own hot ice.

We thought the hot ice science experiment would be easy, but it turns out, there is a trick to it!

How to Make Hot Ice

Making hot ice isn’t difficult, but if you don’t follow the steps correctly, your project will be messed up and you will have to start over.

You want to get it right the first time because this experiment takes MASSIVE amounts of vinegar.

Add this experiment to your list of classic science fair projects to try.

Hot Ice Materials

You’ll need these materials to make hot ice!

• Baking soda
• Aluminum foil
• Rubbing alcohol
• Safety goggles
• Latex gloves

What You Need for a Science Fair

You’ll want to have these supplies on hand before doing your science fair project. Shop the included Amazon storefronts to make things easier and don’t forget to download the free science fair planning checklist before getting started!

Science Fair Project Planning

When you’re planning your project, you want to keep everything organized. Click the image below to get my free science fair project checklist so you can start organizing your project from the start.

You may also want to check out this list of science fair project research supplies.

Supplies for a Science Fair Project

There are so many supplies for science fair projects that are individual to each project, but if you want a general list of possible supplies and inspiration for your project, check out my selection of science fair experiment supplies on Amazon.

Supplies for a Science Fair Presentation

Your science fair presentation is important! It should look presentable and eye-catching. Check out this list of my favorite science fair presentation supplies.

How to do the Hot Ice Experiment With Baking Soda and Vinegar

Wear gloves and eye protection when doing this experiment to keep safe.

To make hot ice, you must boil vinegar and baking soda.

Mix 6 cups of vinegar and 6 tablespoons of baking soda in a pot. Add the baking soda slowly, because you don’t want too big of a reaction. This will create sodium acetate, which can eventually form crystals.

Your experiment might not work the first time (ours didn’t) so keep trying!

We used about a gallon of vinegar before we finally got the experiment to work. We felt like real scientists having to work so hard to make something happen!

Now, boil your sodium acetate mixture down until there is only about 1-2 cups left. Keep the heat as low as you can, otherwise it will turn yellow.

We boiled our vinegar too hot, so our ice turned a bit yellow. That doesn’t affect results, but it does make it look less like ice.

Our crystals finally formed after boiling our fifth batch.

Put your reduced mixture in the refrigerator for about 45 minutes to encourage crystals to form. You may not be able to see them until you pour off the liquid.

Save the liquid for later!

Rinsing the crystals with rubbing alcohol will get rid of some of the yellow color (but not all).

Can you believe this started as six cups of vinegar?

You’ll want to be careful when moving the mixture from the refrigerator to where you plan to pour it out, because if you bump it too much, it could harden in the cup.

Place a few of the crystals on a plate to “seed” your hot ice structures.

Let the kids pour out the vinegar mixture and watch it harden right before your eyes! Pour very carefully to stack the crystals.

After pouring it out, the kids can shape it and play in it safely ( wear latex gloves for maximum protection).

Next time, we’ll try making a giant batch for even more hot ice fun!

More Winter Science Experiments

Burning Ice Science Experiment

How to Make a Magnifying Glass from Ice

How to Make Frost

Galaxy Snow Experiment

Share this project with a friend!