To calculate the enthalpy change for the dissolution of NaCl in water, we need to determine the heat absorbed or released by the water during the process. We can do this using the formula:q = mcTwhere q is the heat absorbed or released, m is the mass of the water, c is the specific heat capacity of water, and T is the change in temperature.First, let's find the change in temperature:T = T_final - T_initialT = 20C - 25CT = -5CNow, we can calculate the heat absorbed or released by the water:q = mcTq = 100 g 4.18 J/ gC -5C q = -2090 JSince the heat absorbed by the water is negative, this means that the water released heat during the dissolution process. Therefore, the enthalpy change for the dissolution of NaCl in water is -2090 J.However, this value is for the dissolution of 10g of NaCl. To find the enthalpy change per mole of NaCl, we need to convert the mass of NaCl to moles:moles of NaCl = mass / molar massmoles of NaCl = 10 g / 58.44 g/molmoles of NaCl = 0.171 molNow, we can calculate the enthalpy change per mole of NaCl:H = q / moles of NaClH = -2090 J / 0.171 molH = -12222 J/molThe enthalpy change for the dissolution of NaCl in water is approximately -12.2 kJ/mol.