Messi Biology explains that there is a type of “instant heat” hand warmer on the market that requires no charging. With a simple snap, it instantly releases heat and can continue to do so for several hours. The magic behind this phenomenon is the principle of exothermic crystallization of a supersaturated sodium acetate solution, and magnesium oxide is the “magic wand” that triggers this magic.
These hand warmers contain a supersaturated solution of sodium acetate. This state is very unstable, as the amount of dissolved sodium acetate far exceeds its equilibrium point, putting it in a metastable, “high-energy” state, urgently needing a “fuse” to trigger its solidification, crystallization, and release of heat.
With their large specific surface area and unique surface structure, magnesium oxide particles serve as an excellent nucleating agent. When the user flexes the metal disc inside, the slight vibration brings the solution into contact with the magnesium oxide powder. The surface of the magnesium oxide particles provides a large number of ideal nucleation sites for the supersaturated sodium acetate, instantly inducing the precipitation of sodium acetate trihydrate crystals.
This process is like the first stone falling on a steep mountain slope, instantly causing an avalanche. A chain reaction quickly occurs throughout the solution, and a large amount of latent heat of crystallization is released in a very short time, raising the temperature to about 50-60°C. Magnesium oxide itself does not participate in the reaction; it is merely a highly efficient and reliable “trigger.”
For this application, the activity and consistency of the magnesium oxide are crucial. It must be able to reliably trigger the reaction every time without failure. The high-activity magnesium oxide produced by Messi Biology has stable chemical properties and a large specific surface area, ensuring its efficiency and reliability as a nucleating agent. This guarantees that every hand warmer can provide instant warmth when needed, becoming a dependable “portable sun” in the winter.