hello da heat comes from idiots all ova da world and der lil brain power collected makes energy and the pouch of liquid transforms it into heat der u will get and A* for dis explanation

They consist of an aqueous solution of sodium acetate with a small “clicker” disk to provide a small clean surface that initiates crystallisation. The solute is dissolved into a solution by prior warning. When heat is required, the disk is “clicked” to scrape a small surface, and this clean surface will initiate the sodium acetate crystallisation from the now supersaturated solution. The heat of crystallisation is slowly released.

y duz it actually matta ain't u got neffin better 2 find out bout

they eat your skin and give off heat from it. then they puke it up and take over the world.

you squeeze them and they pop like a zit. mwa

they work by an exothermic chemcal reaction between the oxidisation of iron when exposed to air. the heat comes from a chrystalization process

by kissing arss

The heat comes from crystalization process (heat of crystallization). the pouch is filled with super-saturated sodium acetate solution. the disc is just a metal which provide "seeding" to start off the crystalization process. When the metal this is bent/squeezed, a tiny particle of metal gets into the solution and acts as a seed of crystalization. Sodium acetate gets crystallized (into whitish solid material) and heat is generated. To reuse the pouch, it is reheated, during which, sodium acetate crystal redissolves in watyer producing super-saturated soln.

sodium is a very reactive alkali metal, and when it comes into contact with the metal disk it causes an exothermic reaction wich gives out the heat that warms your hands. the metal disc is probably got a flourine or clorine compound (depending on the make). all elements have been semi-reacted so they dont catch fire when you have it in yours hands. hope you find this usefull

Demons...