Self-heating chafing dish does not need to be fired or plugged in, but only needs to be poured with cold water, so it can radiate heat to heat the ingredients.

I believe many readers have tasted this kind of self-heating hot pot. No matter how you evaluate it, have you ever wondered how self-heating hot pot can be realized by half a bottle of cold water? Let's discuss its principle together.

give some cold water to get hot?

friends who have bought self-heating hot pot know that the key to self-heating hot pot is a palm-sized heating bag attached to the package.

The packages of heating packages are usually marked with signs such as "No Edible", "No Hot Water" and "Keep Away from Open Fire", and the main components contained in them are calcium oxide (quicklime), aluminum powder and activated carbon.

So, why can a small heating bag give off huge heat to heat or even cook food when it meets cold water?

The heating bag in the hot pot

In the middle school chemistry textbook, we have all learned about endothermic reaction and exothermic reaction. Endothermic reaction means that chemical reaction absorbs heat, and the total energy of reactants is less than the total energy of products; The exothermic reaction is the heat released by chemical reaction, and the total energy of reactants is greater than the total energy of products.

when we put the heating bag of self-heating chafing dish into water, the calcium oxide (CaO) contained in the heating bag will react with water (H21) to generate Ca(OH)2 and a lot of heat, which is expressed by the chemical equation: CaO+H2O=Ca(OH)2.

as the saying goes, it is the process that quicklime becomes hydrated lime when it meets water. In addition, aluminum powder, activated carbon, sodium bicarbonate and other substances in the heating package react with the primary battery, which will release a lot of heat and sometimes release flammable gases such as hydrogen.

in this process, a lot of heat is released, and the air in the closed space is constantly heating up, thus achieving the effect of heating food.

when the heat heats the food on the upper floor, the water in the soup base absorbs the heat and converts it into a large amount of steam, which escapes from the small hole in the pot cover of the self-heating pot, and there is a scene of steaming and fragrant when eating the self-heating pot.

the heating package that is violently reacting

needs to be careful when it is safely heated!

Because of the complexity and instability of the chemicals in the heating package, we must carefully follow the instructions before eating the self-heating hot pot.

First of all, water at room temperature is enough for the chemical reaction of the heating bag. Do not pour hot water on the heating bag for the sake of speed. Hot water will cause violent boiling, which may be dangerous.

second, when heating, the self-heating chafing dish should be placed on the surface of heat-resistant objects, because the temperature at the bottom of the package is extremely high, which may cause the glass to deform and break or leave marks on the glass table.

Third, when heating, be careful not to block the air outlet on the top cover. If the air outlet is blocked carelessly, a large amount of water vapor and hydrogen will be generated and expanded in the package, which will lead to explosion.

finally, let the heating bag fully react with water before throwing it away. If you are not sure, you can consider tying it with a plastic bag before throwing it away. Otherwise, water or rain will enter the narrow trash can to react and generate hydrogen. Although the hydrogen is small and easy to spread, the product calcium hydroxide is corrosive.