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Hot ice is crystallized sodium acetate trihydrate.
If normal sodium acetate dissolved in water crystallises it will generate heat(it's called an exothermic reaction), that's why it's called hot ice.So hot ice isn't real ice: water/H2O in it's solid state.
It's crystallized sodium acetate dissolved in water

Molecular formulas:
Sodium Acetate: NaCH3COO
Sodium Acetate trihydrate: NaCH3COO .3H2O.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. Thecrystallization is an exothermic process, so the resulting ice is hot. Solidification occurs so quickly you can form sculptures as you pour the hot ice.
1. Boil the solution to concentrate the sodiumacetate. 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 orfilm 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. Ifdiscoloration occurs, it's okay.
2. 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 andcovered 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 thecrystals.
3. Place the covered container of sodium acetate solution in the refrigerator to chill.
The sodium acetate in the solution in the refrigerator is an example of a supercooled liquid. Thatis, 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...