The chemical reaction that makes hand warmers heat up is called hot hands.

Oxygen in the air reacts with iron oxide.Military-grade warmers can get as high as 200 degrees, while these hotties can reach up to 163 degrees.Iron powder can be produced by crushing iron or spraying it with water.We eat 2 million pounds of iron powder each year in breakfast cereals.It was delicious!

The chemistry that heats things up is set off by the air that comes in through the fabric pouch.The pouch for toe warmers has more holes than the one for hands since they have less circulation.

The water is held in this porous material.It helps spread heat evenly.In the presence of an oxidizer, heat charcoal.It expands to create millions of tiny pores between its carbon atoms, increasing the surface area to as much as 2,000 square meters per gram.A pound of activated charcoal has the same surface area as six football fields.

Salt makes things happen in your kitchen.Salt can cause car underbellies to fail.NaCl is a handy catalyst that kicks the rust reaction into gear.