When calcium chloride (CaCl2) is added to water, it dissolves and dissociates into calcium ions (Ca2+) and chloride ions (Cl-) in an exothermic process, meaning it releases heat. The dissolution process involves breaking the ionic bonds in solid calcium chloride and the surrounding water molecules forming hydration shells around the ions, which releases a significant amount of heat, warming the solution. This reaction is physical rather than chemical because if the water evaporates, calcium chloride can be recovered. The heat release or enthalpy change is substantial, about 82 kJ per mole of CaCl2 dissolved. The solution contains free Ca2+ and Cl- ions without other chemical changes. Due to the heat produced, care must be taken when mixing calcium chloride into water.