What is Hot Ice?
How Does it Work?
How do you Click It 4 Heat?
What You Will Need:
•1 liter clear vinegar (weak acetic acid)
•4 tablespoons baking soda (sodium bicarbonate)
Making Your Own Hot Ice.
Prepare the Sodium Acetate or Hot Ice
1.In a saucepan or large beaker, 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+[HCO3]– + CH3–COOH → CH3–COO– Na+ + H2O + CO2
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 took me about an hour on the stove over medium heat. If you use lower heat you are less likely to get yellow or brown liguid, but it will take longer. If discoloration occurs, it's okay.
3.Once you remove the sodium acetate solution from heat, immediately cover it to prevent any further evaporation. I poured my solution into a separate container and covered it 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.
4.Place the covered container of sodium acetate solution in the refrigerator to chill.
Click It 4 Heat? - An Exothermic Reaction
An exothermic reaction is a chemical reaction that is accompanied by the release of heat. It gives out energy to its surroundings. The energy needed for the reaction to occur is less than the total energy released.
Hot Ice refers to a chemistry demonstration involving a supersaturated solution of Sodium Acetate which, when disturbed, will appear to freeze into "ice" as the cold solution turns from a liquid into a solid state in a matter of seconds. This process is exothermic and the resulting "ice" is warm to the touch, contrary to what one would expect of ordinary ice.
You can supercool hot ice or sodium acetate so that it will remain a liquid below its melting point. You can trigger crystallization on command, forming sculptures as the liquid solidifies. The reaction is exothermic so heat is generated by the hot ice.
The sodium acetate in the solution in the refrigerator is an example of a supercooled liquid. That is, the sodium acetate exists in liquid form below its usual melting point. You can initiate crystallization by adding a small crystal of sodium acetate or possibly even by touching the surface of the sodium acetate solution with a spoon or finger. The crystallization is an example of an exothermic process. Heat is released as the 'ice' forms. To demonstrate supercooling, crystallization, and heat release you could: •Drop a crystal into the container of cooled sodium acetate solution. The sodium acetate will crystallize within seconds, working outward from where you added the crystal. The crystal acts as a nucleation site or seed for rapid crystal growth. Although the solution just came out of the refrigerator, if you touch the container you will find it is now warm or hot.
•Pour the solution onto a shallow dish. If the hot ice does not spontaneously begin crystallization, you can touch it with a crystal of sodium acetate (you can usually scrape a small amount of sodium acetate from the side of the container you used earlier). The crystallization will progress from the dish up toward where you are pouring the liquid. You can construct towers of hot ice. The towers will be warm to the touch.
•You can re-melt sodium acetate and re-use it for demonstrations.
Hot Ice Safety
As you would expect, sodium acetate is a safe chemical for use in demonstrations. It is used as a food additive to enhance flavor and is the active chemical in many hot packs. The heat generated by the crystallization of a refrigerated sodium acetate solution should not present a burn hazard.
Click It Hot accepts no responsibility in the making or the safety of performing this experiment. As always, no experiment should be done without parental guidance.
"When the Hot Ice solution is triggered (possibly by the addition of a seed crystal), the dissolved Sodium Acetate comes out of solution and returns to a solid form. Furthermore, the solid Sodium Acetate can absorb water into its crystal lattice, becoming Sodium Acetate Trihydrate (NaC2H3O2 ● 3 H2O) in the process. The hydration of Sodium Acetate is exothermic and heat is released in the process, explaining why the Sodium Acetate crystals are warm even though the supersaturated solution was initially cold." Amazingrust.com
"Since supersaturated solutions contain more dissolved solute than would normally exist in equilibrium they exist in a meta-stable state, similar to that of a ball sitting at the apex of a steep mountain. As long as nothing happens to the solution, like the ball sitting precariously atop the mountain, it will continue on in that state. However, the slightest “nudge” in any direction and the supersaturated solution (and the ball) will try to restore itself to its most stable state by precipitating solute out of solution (or rolling down to the bottom of the mountain in the case of the ball)."