Barium hydroxide octahydrate (Ba(OH)₂·8H₂O) and ammonium chloride (NH₄Cl) create an endothermic reaction ideal for salt refrigerators and instant cold packs. When mixed with water, these compounds absorb heat, rapidly cooling their surroundings. The reaction, Ba(OH)₂·8H₂O + 2NH₄Cl → BaCl₂·2H₂O + 2NH₃ + 8H₂O, is driven by positive enthalpy and entropy changes, making it spontaneous and […]