Question

Calculate the standard enthalpy of precipitation for the reaction: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) given that the standard enthalpies of formation for AgNO3(aq), NaCl(aq), AgCl(s), and NaNO3(aq) are -123.2 kJ/mol, -407.3 kJ/mol, -127.0 kJ/mol, and -467.3 kJ/mol, respectively.

Answer 1

To calculate the standard enthalpy of precipitation for the reaction, we can use the following equation:H_reaction =  H_f products  -  H_f reactants where H_reaction is the standard enthalpy of precipitation, H_f products  is the sum of the standard enthalpies of formation of the products, and H_f reactants  is the sum of the standard enthalpies of formation of the reactants.For the given reaction:H_reaction = [ -127.0 kJ/mol  +  -467.3 kJ/mol ] - [ -123.2 kJ/mol  +  -407.3 kJ/mol ]H_reaction =  -594.3 kJ/mol  -  -530.5 kJ/mol H_reaction = -63.8 kJ/molThe standard enthalpy of precipitation for the reaction is -63.8 kJ/mol.