Question

Silver iodide is a very insoluble compound. Please give reasons for compounds like silver sulfate or silver chloride to be insoluble that relate to lattice energy versus energy of hydration.

Answer 1

1) If the hydration energy is equal to or greater than the lattice energy, then the salt is water-soluble

     hydration enrgy    > lattice energy : (water soluble)

2) If the hydration energy is less than the lattice energy, then the salt is water-insoluble.

hydration enrgy   < lattice energy : (water insoluble)

for salts like AgCl , Ag2SO4 lattice energy is more . so hydration energy cannot overcome the intermolecular forces between Ag+ and Cl- ions . so it is insoluble in water