First, we need to determine the number of moles of ethanol and water in the solution.The molar mass of ethanol C2H5OH is: 2 * 12.01 g/mol for C + 6 * 1.01 g/mol for H + 1 * 16.00 g/mol for O = 46.07 g/molThe molar mass of water H2O is: 2 * 1.01 g/mol for H + 1 * 16.00 g/mol for O = 18.02 g/molNow, we can calculate the number of moles of each substance:Moles of ethanol = 50 g / 46.07 g/mol = 1.085 molMoles of water = 250 g / 18.02 g/mol = 13.87 molSince the heat of mixing is given per mole of ethanol and water, we need to find the total moles of the mixture:Total moles = moles of ethanol + moles of water = 1.085 mol + 13.87 mol = 14.955 molNow, we can calculate the heat released or absorbed during the mixing process:Heat released/absorbed = heat of mixing * total moles Heat released/absorbed = -5.02 kJ/mol * 14.955 mol = -75.11 kJSince the heat of mixing is negative, it indicates that the heat is released during the mixing process. Therefore, the heat released when the two substances are mixed is 75.11 kJ.