Answer to Question #139457 in Inorganic Chemistry for Sarita bartwal

Question

The lattice enthalpies of NaCl, kCl, AgCl are -787,-717,-916 kjmol^-1, respectively. Based on these values, arrange them increasing order of water solubility and justify your answer

Answer 1

$AgCl< NaCl<KCl$

There is a relation between the lattice enthalpies and solubility in water. The lattice energy is the amount of energy required to separate the lattice into gaseous ions. But when the lattice is formed from ions, you should talk about lattice formation enthalpy which corresponds to the energy released so will have a negative sign. In the simplest approach, if the lattice energy decreases, solubility will increase, because of smaller energy required to separate ions, thus simpler to get dissolved compound.