To calculate the enthalpy change of dissolving potassium chloride KCl in water, we need to know the heat of solution of KCl. The heat of solution Hsol is the amount of heat absorbed or released when a solute dissolves in a solvent. For KCl, the heat of solution is approximately -17.2 kJ/mol.First, we need to determine the number of moles of KCl in 15.0 grams:Molar mass of KCl = 39.1 g/mol K + 35.5 g/mol Cl = 74.6 g/molNumber of moles of KCl = 15.0 g / 74.6 g/mol = 0.201 molNext, we can calculate the enthalpy change for dissolving 0.201 mol of KCl:H = Hsol * moles of KCl H = -17.2 kJ/mol * 0.201 mol = -3.46 kJThe enthalpy change of dissolving 15.0 grams of potassium chloride KCl in 250 mL of water is -3.46 kJ. Since the value is negative, it indicates that the dissolving process is exothermic, meaning heat is released during the dissolution of KCl in water.