I need someone to explain the process of making hot ice using sodium acetate (scientifically). THNX!?

Question

I need to know what exactly happens with the chemical stuff for my science fair, anybody who's good in chemistry..please help and explain well, THANKS ALOTT!

Answer 1

Sodium acetate itself is made from Acetic acid and Sodium hydroxide:

CH3CO2H + NaOH -> CH3CO2Na + H2O

This is the reaction of a weak acid with a strong base. The products are the Sodium salt of a weak acid and water. The common name of Sodium hydroxide is "lye" and Aacetic acid is what gives vinegar its sour taste and sharp smell.

There is almost always an exchange of energy when a material changes phases. Phase changes involve things such as freezing, boiling or melting. Energy either enters or exits the material, usually in the form of heat. Crystallization is another phase change. "Hot ice" is a supersaturated solution of Sodium acetate. Supersaturated solutions are holding more material than they ordinarily do at a certain temperature. Such a system is unstable, and it is easy to cause the solution to spontaneously crystallize. This is what happens when the packet of "hot ice" is bent and twisted. As the Sodium acetate forms crystals, it realeases energy in the form of heat. This warms the packet. Once the packet cools, it ought to be possible to place it in boilng water to redissolve the crystals. If the water is allowed to cool slowly, the solution will supersaturate again. The packet will then be ready to be used again. I've never actually used "hot ice" but I understand the physics and chemistry involved, so the packet ought to be able to be recharged.

Answer 2

There's no chemical reaction. The hot ice process is simply a rapid recrystallization that happens to be exothermic. This trick works because of how highly crystalline sodium acetate is. To do the trick, add sodium acetate to a pan of boiling water until no more solid can dissolve. You will reach this point when you see solids remaining on the bottom of the pan. This boiling solution of sodium acetate is now supersaturated. Remove the solution from the stove top and allow to cool for a few minutes, then pour the homogeneous liquid it into a glass container. Be sure not to include the undissolved sodium acetate. Place the container(s) in a refrigerator to cool even more. Then, all you need to do is touch the surface of the clear solution and wa-la! Presto chango, you've made what appears to be hot ice! This is because the crystallized sodium acetate looks like ice and, since the crystallization process is exothermic, it feels hot to the touch. Pretty kewl trick. See the link below for a video explanation and demonstration of the process...