Question

Calculate the standard enthalpy change for the precipitation reaction: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) Given that the standard enthalpy of formation (∆Hf) for AgNO3(aq), NaCl(aq), AgCl(s), and NaNO3(aq) are -123.1 kJ/mol, -407.3 kJ/mol, -127.0 kJ/mol, and -467.3 kJ/mol respectively.

Answer 1

To calculate the standard enthalpy change for the precipitation reaction, we can use the following equation:H_reaction =  Hf products  -  Hf reactants For the given reaction:AgNO3 aq  + NaCl aq   AgCl s  + NaNO3 aq The standard enthalpy of formation for the products are:Hf AgCl  = -127.0 kJ/molHf NaNO3  = -467.3 kJ/molThe standard enthalpy of formation for the reactants are:Hf AgNO3  = -123.1 kJ/molHf NaCl  = -407.3 kJ/molNow, we can plug these values into the equation:H_reaction = [ -127.0  +  -467.3 ] - [ -123.1  +  -407.3 ]H_reaction =  -594.3  -  -530.4 H_reaction = -63.9 kJ/molThe standard enthalpy change for the precipitation reaction is -63.9 kJ/mol.