To calculate the enthalpy change of solution for 2.0 moles of sodium chloride, we can use the following formula:H_solution = moles molar heat of solutionGiven:moles of sodium chloride = 2.0 molesmolar heat of solution = -3.91 kJ/molNow, we can plug in the values into the formula:H_solution = 2.0 moles -3.91 kJ/mol H_solution = -7.82 kJSo, the enthalpy change of solution for 2.0 moles of sodium chloride in 500.0 mL of water at 25C is -7.82 kJ.