answer : -2413.6 kJ
Na2SO4 molar mass = 142 g / mol
Na2SO4 weight = 246.4 g
Na2SO4 moles = 246.4 / 142
                       Â
= 1.74
for 1 mole Na2SO4 dissoves in water the change in enthalpy =
-1387.1 kJ
for 1.74 mole Na2SO4 dissoves in water the change in enthalpy =
-1.74 x 1387.1 kJ
                                                                                                       Â
= -2413.6 kJ
