Warm baby, also called warm paste, is a tool for heating. The reaction principle is to use the primary battery to accelerate the oxidation reaction and convert chemical energy into heat energy. In order to keep the temperature longer, vermiculite, a mineral material, is used to keep warm.

Basic principles:

Because it can't react before use, the material of the bag should be very special, consisting of raw material layer, gelatin layer and non-woven bag. Non-woven bag adopts microporous breathable film, and there are also conventional airtight outer bags. When in use, the outer bag is removed, so that the inner bag (non-woven bag) is exposed to the air, and oxygen in the air enters the interior through the breathable film.

The time and temperature of heat release are controlled by the oxygen permeability of the gas permeable membrane. If oxygen permeates too quickly, heat will be released at once, which may burn the skin. If oxygen permeates too slowly, there will be no temperature. It is a dark brown solid after use, containing carbon powder, NaCl solid, Fe2O3 solid and magnesium aluminum salt.

Negative electrode: Fe-2e-=Fe2+.

Positive electrode: O2? + 2H2O + 4e-=4OH-.

Total reaction: 2Fe+O2? + 2H2O=2Fe(OH)2 .

4Fe(OH)2？ + 2H2O + O2=4Fe(OH)3↓2Fe(OH)3？ ==== Fe2O3+3H2O .