The NBS tables (Sec. 5.9) give at 25°C Δf H°NaCl(s) = -411.153 kJ/mol and give the followi...

The NBS tables (Sec. 5.9) give at 25°C Δf H°NaCl(s) = -411.153 kJ/mol and give the following apparent Δf H°data in kJ/mol for aqueous NaCl solutions at 25°C:

The value -409.279 kJ/mol as the apparent enthalpy of formation of 1 mol of NaCl in 9 mol of H2O means that when 1 mol of NaCl(s) is dissolved in 9 mol of H2O(l) at 25°C and 1 bar, the enthalpy change is

-409.279 kJ/mol - (-411.153 kJ/mol) = 1.874 kJ/mol

Calculate and plot ΔmixH/n versus xNaCl and use the intercept method to find and at xNaCl =0.05, where  is for solid NaCl.