Exothermic hand warmers

Exothermic hand warmers Hand warmers work when you expose them to air. Once you have done this it causes a rusting inside the packet. The warmer contains water, cellulose, iron, vermiculite, activated carbon and salt. When exposed to air, these things cause the iron to rust at a slow rate which produces heat.

This is the word equation for the reaction:
Calcium monoxide + water >> calcium hydroxide + heat

This is the symbol equation for the reaction:
CaO + H2O >> Ca(OH)2 + heat