To calculate the standard enthalpy change H for the precipitation reaction, we need to use the standard enthalpies of formation Hf of the reactants and products. The equation to calculate H is:H = Hf products - Hf reactants The standard enthalpies of formation for the compounds involved in the reaction are as follows:Hf AgNO3 aq = -124.4 kJ/molHf NaCl aq = -407.3 kJ/molHf AgCl s = -127.0 kJ/molHf NaNO3 aq = -365.6 kJ/molNow, we can plug these values into the equation:H = [ -127.0 kJ/mol + -365.6 kJ/mol ] - [ -124.4 kJ/mol + -407.3 kJ/mol ]H = -492.6 kJ/mol - -531.7 kJ/mol H = 39.1 kJ/molThe standard enthalpy change for the precipitation reaction between aqueous silver nitrate and aqueous sodium chloride to form solid silver chloride and aqueous sodium nitrate is 39.1 kJ/mol.