To calculate the enthalpy of solution, we first need to determine the heat q released or absorbed during the dissolution process. We can use the formula:q = mcTwhere m is the mass of the solution, c is the specific heat capacity, and T is the change in temperature.First, let's find the mass of the solution. We know that the mass of KCl is 10.0 g and the volume of water is 100 mL. Assuming the density of water is 1 g/mL, the mass of water is:mass of water = volume of water density of water = 100 mL 1 g/mL = 100 gNow, we can find the mass of the solution:mass of solution = mass of KCl + mass of water = 10.0 g + 100 g = 110 gNext, we can find the change in temperature:T = T_final - T_initial = 20C - 25C = -5CNow, we can calculate the heat q using the formula:q = mcT = 110 g 4.184 J/gC -5C = -2296.2 JSince the temperature of the solution decreases, the dissolution process is exothermic, and the heat is released to the surroundings. Therefore, q = -2296.2 J.Finally, we can calculate the enthalpy of solution H_solution per mole of KCl. First, we need to find the number of moles of KCl:Molar mass of KCl = 39.10 g/mol K + 35.45 g/mol Cl = 74.55 g/molmoles of KCl = mass of KCl / molar mass of KCl = 10.0 g / 74.55 g/mol = 0.134 molNow, we can find the enthalpy of solution per mole of KCl:H_solution = q / moles of KCl = -2296.2 J / 0.134 mol = -17135 J/molThe enthalpy of solution for potassium chloride is approximately -17.1 kJ/mol.