The powder helps the soldier have a hot meal for 10 minutes

Magnesium powder, iron and salt react with water to produce more heat, which helps the solder quickly heat up the rations.

When fighting on the battlefield, the soldier does not have much time to prepare meals, while the energy needs are huge after the maneuver, tired combat. To address this problem, many countries around the world provide soldiers with field- based food packages (MREs).

One of the most important features of MRE is the ability to self-heal without the stove. Soldiers simply add water to activate a heat-sensitive chemical chain, heating food on the spot, according to How Stuff Works.

Package MRE heating without stove.

Thermal reactions are common in nature, typically metal oxidation. The MRE heating principle is based on the oxidation of magnesium, which generates large amounts of heat in a short time.

Magnesium powder is mixed with salt and iron powder, this mixture is contained in a plastic bag that comes with MRE. When water is added, the reaction will take place in a few seconds and boil the water. The soldier only needs to pack the mixture into the food bag, the heat generated from the reaction will heat the food for a few minutes.

If there is only magnesium and water, the reaction will occur too slowly, not generating enough heat as required. The appearance of iron powder and salt is the key to accelerating the reaction. Water dissolves salt, producing electrolyte containing magnesium and iron. The contact between magnesium and iron produces a catalytic reaction, the source of the initial heat of water.

Magnesium-iron-salt mixture comes in the MRE. (Image: Wordpress)

The 8 g heat mix in each US Army MRE package usually contains 95% magnesia powder and 5% iron powder. After adding 30 ml of water, this mixture can produce 50 KJ of heat to heat up the 230 g food package to 37 degrees Celsius within 10 minutes.