Final answer:
Flameless ration heaters produce heat through the exothermic oxidation of powdered iron when activated, with additives like salt to catalyze the reaction and materials like cellulose for even heat distribution.
Step-by-step explanation:
The heat in a flameless ration heater is produced through an exothermic chemical reaction. When activated, typically by water, the heater contains a mixture of powdered metals, such as iron, which rapidly oxidizes in the presence of oxygen from the surrounding air. The reaction can be depicted as 4Fe(s) + 3O₂ (g) → 2Fe₂O₃(s), where iron(Fe) reacts with oxygen(O₂) to form iron oxide(Fe₂O₃), releasing heat in the process. Additives like salt act as a catalyst to speed up the reaction and produce heat more rapidly. Furthermore, materials like cellulose, vermiculite, and activated carbon are included to help distribute the heat evenly.