There is a small hot water bottle, a small pinch of iron will be fever, why?
To understand the principles of warm handbags, we first need to know what is supersaturated solution. At a certain temperature, the solubility of the solute in the solvent is unchanged. For example, the solubility of Nacl in water at room temperature is 36g/100mL water. When the concentration of the solution is equal to that of the solution, the solution is called a saturated solution. When the concentration of the solution is higher than that of the solution, the solution is called a supersaturated solution. The liquid in a warm bag is a supersaturated solution of sodium acetate (CH3COONa).Because the concentration of supersaturated solution is too high, it is not stable. When we twist the sheet of metal inside, a slight shock is enough to crystallize the solute into a stable solid. However, the process is exothermic, so warm handbags start to warm up.There is an advantage of warm handbags that can be recycled. As long as the warm hand is placed in boiling water for about 10 minutes, the condensate will be dissolved again. In the process of dissolving, the solute absorbs heat and becomes supersaturated solution again.
The principle is that the bag filled with liquid is a supersaturated solution of sodium acetate (sodium acetate, CH3COONa). Because the concentration of supersaturated solution is too high, it is not stable. When a sheet of metal is twisted, a slight vibration is enough to cause the solute to crystallize and become a more stable solid, but the process is exothermic, so the warm bag begins to heat up.
Homemade magic warm handbag1 175g sodium acetate (CH3COONa) into a beaker containing 50mL water:2 dissolve sodium acetate in beaker with hot tub;3 pour the solution into a fresh bag and add a piece of twisted metal
