Science, Tech, Math › Science Make Hot Ice - Heating Pad Chemistry Make Your Own Chemical Hot Pack Share Flipboard Email Print Sodium acetate is called hot ice because it's hot and resembles an ice cube. The chemical can be used to make hot packs. ICT_Photo / Getty Images Science Chemistry Projects & Experiments Basics Chemical Laws Molecules Periodic Table Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated March 08, 2017 Here's an easy chemistry project you can do in which you take a clear liquid and instantaneously solidify it into hot 'ice'. It isn't water ice, however. This is how you make crystals of sodium acetate, which is used in hand warmers and chemical heating pads and hot packs. Hot Ice Materials sodium acetatewatersaucepanglass or pan Making Your Own Sodium Acetate Monohydrate If you don't have any sodium acetate monohydrate you can make your own. Add baking soda (sodium bicarbonate) to vinegar (weak acetic acid) until the mixture stops fizzing. This will give you an aqueous solution of sodium acetate. If you boil off the water, you'll be left with the sodium acetate. Expect to use a lot of baking soda and vinegar if you go this route. Make the Hot Ice What you are going to do is make a supersaturated sodium acetate solution. The solution will remain a supercooled liquid until a little solid sodium acetate is introduced. This will cause rapid crystallization that will resemble a block of ice, except it will be hot to the touch and not edible. Dump some sodium acetate monohydrate into a saucepan.Add just enough water to dissolve the sodium acetate.Heat the solution to just below its boiling point.Stir in more sodium acetate. Keep stirring and adding sodium acetate until you start to see solid material accumulating at the bottom of the pan.Pour the hot solution into a glass or other container. Do not allow any of the undissolved solid to enter the container.Cool the solution in the refrigerator 30 minutes to an hour.Remove the solution from the refrigerator. As long as you didn't leave any solid sodium acetate in the solution, it should still be liquid.When you are ready to make 'ice' introduce a little of the solid sodium acetate. You could dip a toothpick or the edge of a spoon in sodium acetate powder.The crystallization will evolve heat (exothermic reaction), making the solid feel hot to the touch (~130° F). Hot Ice Trick You don't have to solidify the sodium acetate in a dish. You can crystallize it as the solution is being poured to make fantastic shapes.